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    AuthorTitleYearJournal/ProceedingsReftypeDOI/URL
    Chernenkaya, A., Medjanik, K., Nagel, P., Merz, M., Schuppler, S., Canadell, E., Pouget, J.-P. and Schönhense, G. Nature of the empty states and signature of the charge density wave instability and upper Peierls transition of TTF-TCNQ by temperature-dependent NEXAFS spectroscopy 2015 Eur. Phys. J. B
    Vol. 88(1) 
    article DOI  
    BibTeX:
    @article{Chernenkaya2015a,
      author = {Chernenkaya, Alisa and Medjanik, Katerina and Nagel, Peter and Merz, Michael and Schuppler, Stefan and Canadell, Enric and Pouget, Jean-Paul and Schönhense, Gerd},
      title = {Nature of the empty states and signature of the charge density wave instability and upper Peierls transition of TTF-TCNQ by temperature-dependent NEXAFS spectroscopy},
      journal = {Eur. Phys. J. B},
      publisher = {Springer Science + Business Media},
      year = {2015},
      volume = {88},
      number = {1},
      doi = {http://dx.doi.org/10.1140/epjb/e2014-50481-9}
    }
    
    Kutnyakhov, D., Elmers, H.J., Schönhense, G., Tusche, C., Borek, S., Braun, J., Minar, J. and Ebert, H. Specular reflection of spin-polarized electrons from the W(001) spin-filter crystal in a large range of scattering energies and angles 2015 Phys. Rev. B
    Vol. 91(1), pp. 014416- 
    article DOI  
    BibTeX:
    @article{Kutnyakhov2015,
      author = {Kutnyakhov, D. and Elmers, H. J. and Schönhense, G. and Tusche, C. and Borek, S. and Braun, J. and Minar, J. and Ebert, H.},
      title = {Specular reflection of spin-polarized electrons from the W(001) spin-filter crystal in a large range of scattering energies and angles},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2015},
      volume = {91},
      number = {1},
      pages = {014416--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.91.014416}
    }
    
    Nepijko, S., Chernenkaya, A., Medjanik, K., Chernov, S., Klimenkov, M., Vlasenko, O., Petrovskaya, S., Odnodvorets, L., Zaulichnyy, Y. and Schönhense, G. Soft X-ray emission spectroscopy used for the characterization of a-C and CNx thin films 2015 Thin Solid Films
    Vol. 577, pp. 109-113 
    article DOI  
    BibTeX:
    @article{Nepijko2015,
      author = {Nepijko, S.A. and Chernenkaya, A. and Medjanik, K. and Chernov, S.V. and Klimenkov, M. and Vlasenko, O.V. and Petrovskaya, S.S. and Odnodvorets, L.V. and Zaulichnyy, Ya.V. and Schönhense, G.},
      title = {Soft X-ray emission spectroscopy used for the characterization of a-C and CNx thin films},
      journal = {Thin Solid Films},
      publisher = {Elsevier BV},
      year = {2015},
      volume = {577},
      pages = {109-113},
      doi = {http://dx.doi.org/10.1016/j.tsf.2015.01.065}
    }
    
    Jourdan, M., Minar, J., Braun, J., Kronenberg, A., Chadov, S., Balke, B., Gloskovskii, A., Kolbe, M., Elmers, H., Schönhense, G. and et al. Direct observation of half-metallicity in the Heusler compound Co2MnSi 2014 Nature Communications
    Vol. 5 
    article DOI  
    BibTeX:
    @article{Jourdan2014,
      author = {Jourdan, M. and Minar, J. and Braun, J. and Kronenberg, A. and Chadov, S. and Balke, B. and Gloskovskii, A. and Kolbe, M. and Elmers, H.J. and Schönhense, G. and et al.},
      title = {Direct observation of half-metallicity in the Heusler compound Co2MnSi},
      journal = {Nature Communications},
      publisher = {Nature Publishing Group},
      year = {2014},
      volume = {5},
      doi = {http://dx.doi.org/10.1038/ncomms4974}
    }
    
    Medjanik, K., de Souza, M., Kutnyakhov, D., Gloskovskii, A., Müller, J., Lang, M., Pouget, J.-P., Foury-Leylekian, P., Moradpour, A., Elmers, H.-J. and Schönhense, G. Hard X-ray photoemission study of the Fabre salts (TMTTF)2X (X = SbF6 and PF6) 2014 The European Physical Journal B
    Vol. 87(256)(11)The European Physical Journal B, pp. 1-8 
    article DOI  
    BibTeX:
    @article{Medjanik2014,
      author = {Medjanik, Katerina and de Souza, Mariano and Kutnyakhov, Dmytro and Gloskovskii, Andrei and Müller, Jens and Lang, Michael and Pouget, Jean-Paul and Foury-Leylekian, Pascale and Moradpour, Alec and Elmers, Hans-Joachim and Schönhense, Gerd},
      title = {Hard X-ray photoemission study of the Fabre salts (TMTTF)2X (X = SbF6 and PF6)},
      booktitle = {The European Physical Journal B},
      journal = {The European Physical Journal B},
      publisher = {Springer Berlin Heidelberg},
      year = {2014},
      volume = {87(256)},
      number = {11},
      pages = {1-8},
      doi = {http://dx.doi.org/10.1140/epjb/e2014-50499-y}
    }
    
    Nepijko, S., Chernenkaya, A., Medjanik, K., Chernov, S., Shapko, D., Protsenko, I., Schulze, W. and Schönhense, G. Investigation of a Ge nanoparticle film by means of electron stimulated photon emission spectroscopy 2014 Journal of Electron Spectroscopy and Related Phenomena
    Vol. 193, pp. 54¬タモ57 
    article DOI  
    BibTeX:
    @article{Nepijko2014,
      author = {Nepijko, S.A. and Chernenkaya, A. and Medjanik, K. and Chernov, S.V. and Shapko, D.V. and Protsenko, I.Yu. and Schulze, W. and Schönhense, G.},
      title = {Investigation of a Ge nanoparticle film by means of electron stimulated photon emission spectroscopy},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      publisher = {Elsevier BV},
      year = {2014},
      volume = {193},
      pages = {54¬タモ57},
      doi = {http://dx.doi.org/10.1016/j.elspec.2014.03.006}
    }
    
    Schwander, D., Berg, T., Harries, D., Schönhense, G. and Ott, U. Composition and clues to the origin of refractory metal nuggets extracted from chondritic meteorites 2014 Meteoritics & Planetary Science
    Vol. 49(10), pp. 1888-1901 
    article DOI  
    BibTeX:
    @article{Schwander2014a,
      author = {Schwander, D. and Berg, T. and Harries, D. and Schönhense, G. and Ott, U.},
      title = {Composition and clues to the origin of refractory metal nuggets extracted from chondritic meteorites},
      journal = {Meteoritics & Planetary Science},
      publisher = {Wiley-Blackwell},
      year = {2014},
      volume = {49},
      number = {10},
      pages = {1888-1901},
      doi = {http://dx.doi.org/10.1111/maps.12366}
    }
    
    Schwander, D., Berg, T., Schönhense, G. and Ott, U. Condensation of refractory metals in asymptotic giant branch and other stellar environments 2014 The Astrophysical Journal
    Vol. 793(1), pp. 20 
    article DOI  
    BibTeX:
    @article{Schwander2014,
      author = {Schwander, D. and Berg, T. and Schönhense, G. and Ott, U.},
      title = {Condensation of refractory metals in asymptotic giant branch and other stellar environments},
      journal = {The Astrophysical Journal},
      publisher = {IOP Publishing},
      year = {2014},
      volume = {793},
      number = {1},
      pages = {20},
      doi = {http://dx.doi.org/10.1088/0004-637x/793/1/20}
    }
    
    Chernov, S.V., Makukha, Z.M., Protsenko, I.Y., Nepijko, S.A., Elmers, H.J. and Schönhense, G. Test object for emission electron microscope 2013 Applied Physics A
    Vol. 114(4), pp. 1383-1385 
    article DOI  
    BibTeX:
    @article{Chernov2013,
      author = {Chernov, S. V. and Makukha, Z. M. and Protsenko, I. Y. and Nepijko, S. A. and Elmers, H. J. and Schönhense, G.},
      title = {Test object for emission electron microscope},
      journal = {Applied Physics A},
      publisher = {Springer Science + Business Media},
      year = {2013},
      volume = {114},
      number = {4},
      pages = {1383-1385},
      doi = {http://dx.doi.org/10.1007/s00339-013-8010-y}
    }
    
    Elmers, H.J., Chernenkaya, A., Medjanik, K., Emmel, M., Jakob, G., Schönhense, G., Gottlob, D., Krug, I., de Groot, F.M.F. and Gloskovskii, A. Exchange coupling in the correlated electronic states of amorphous GdFe films 2013 Phys. Rev. B
    Vol. 88(17) 
    article DOI  
    BibTeX:
    @article{Elmers2013,
      author = {Elmers, H. J. and Chernenkaya, A. and Medjanik, K. and Emmel, M. and Jakob, G. and Schönhense, G. and Gottlob, D. and Krug, I. and de Groot, F. M. F. and Gloskovskii, A.},
      title = {Exchange coupling in the correlated electronic states of amorphous GdFe films},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society (APS)},
      year = {2013},
      volume = {88},
      number = {17},
      doi = {http://dx.doi.org/10.1103/physrevb.88.174407}
    }
    
    Klaer, P., Schertz, F., Lehr, M., Schönhense, G. and Elmers, H.J. Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100) 2013 Phys. Rev. B
    Vol. 88(21) 
    article DOI  
    BibTeX:
    @article{Klaer2013,
      author = {Klaer, P. and Schertz, F. and Lehr, M. and Schönhense, G. and Elmers, H. J.},
      title = {Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100)},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society (APS)},
      year = {2013},
      volume = {88},
      number = {21},
      doi = {http://dx.doi.org/10.1103/physrevb.88.214425}
    }
    
    Klanke, J., Rentschler, E., Medjanik, K., Kutnyakhov, D., Schoenhense, G., Krasnikov, S., Shvets, I.V., Schuppler, S., Nagel, P., Merz, M. and Elmers, H.J. Beyond the Heisenberg Model: Anisotropic Exchange Interaction between a Cu-Tetraazaporphyrin Monolayer and Fe3O4(100) 2013 Physical Review Letters
    Vol. 110(13), pp. 137202 
    article DOI  
    Abstract: The exchange coupling of a single spin localized at the central ion of Cu-tetraazaporphyrin on a magnetite(100) surface has been studied using x-ray magnetic circular dichroism (XMCD). Sum rule analysis of the XMCD spectra results in Cu spin and orbital magnetic moments as a function of the applied external field at low temperatures (20 K). The exchange coupling is positive for magnetization direction perpendicular to the surface (ferromagnetic) while it is negative for in-plane magnetization direction (antiferromagnetic). We attribute the anisotropy of the Heisenberg exchange coupling to an orbitally dependent exchange Hamiltonian. DOI: 10.1103/PhysRevLett.110.137202
    BibTeX:
    @article{Klanke2013,
      author = {Klanke, J. and Rentschler, E. and Medjanik, K. and Kutnyakhov, D. and Schoenhense, G. and Krasnikov, S. and Shvets, I. V. and Schuppler, S. and Nagel, P. and Merz, M. and Elmers, H. J.},
      title = {Beyond the Heisenberg Model: Anisotropic Exchange Interaction between a Cu-Tetraazaporphyrin Monolayer and Fe3O4(100)},
      journal = {Physical Review Letters},
      year = {2013},
      volume = {110},
      number = {13},
      pages = {137202},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.110.137202}
    }
    
    Kutnyakhov, D., Lushchyk, P., Fognini, A., Perriard, D., Kolbe, M., Medjanik, K., Fedchenko, E., Nepijko, S.A., Elmers, H.J., Salvatella, G., Stieger, C., Gort, R., Baehler, T., Michlmayer, T., Acremann, Y., Vaterlaus, A., Giebels, F., Gollisch, H., Feder, R., Tusche, C., Krasyuk, A., Kirschner, J. and Schoenhense, G. Imaging spin filter for electrons based on specular reflection from iridium (001) 2013 Ultramicroscopy
    Vol. 130, pp. 63–69 
    article DOI  
    Abstract: As Stern-Gerlach type spin filters do not work with electrons, spin analysis of electron beams is accomplished by spin-dependent scattering processes based on spin-orbit or exchange interaction. Existing polarimeters are single-channel devices characterized by an inherently low figure of merit (FoM) of typically 10(-4)-10(-3). This single-channel approach is not compatible with parallel imaging microscopes and also not with modern electron spectrometers that acquire a certain energy and angular interval simultaneously. We present a novel type of polarimeter that can transport a full image by making use of k-parallel conservation in low-energy electron diffraction. We studied specular reflection from Ir (001) because this spin-filter crystal provides a high analyzing power combined with a "lifetime" in UHV of a full day. One good working point is centered at 39 eV scattering energy with a broad maximum of 5 eV usable width. A second one at about 10 eV shows a narrower profile but much higher FoM. A relativistic layer-KKR SPLEED calculation shows good agreement with measurements. (C) 2013 Elsevier BY. All rights reserved.
    BibTeX:
    @article{Kutnyakhov2013,
      author = {Kutnyakhov, D. and Lushchyk, P. and Fognini, A. and Perriard, D. and Kolbe, M. and Medjanik, K. and Fedchenko, E. and Nepijko, S. A. and Elmers, H. J. and Salvatella, G. and Stieger, C. and Gort, R. and Baehler, T. and Michlmayer, T. and Acremann, Y. and Vaterlaus, A. and Giebels, F. and Gollisch, H. and Feder, R. and Tusche, C. and Krasyuk, A. and Kirschner, J. and Schoenhense, G.},
      title = {Imaging spin filter for electrons based on specular reflection from iridium (001)},
      journal = {Ultramicroscopy},
      year = {2013},
      volume = {130},
      pages = {63–69},
      doi = {http://dx.doi.org/10.1016/j.ultramic.2013.03.017}
    }
    
    Nepijko, S.A., Elmers, H.J., Schoenhense, G., Demydenko, M.H., Protsenko, S.I. and Kostyuk, D.M. Magnetoresistive properties of Fe3O4 nanoparticles embedded in a Cu matrix 2013 Applied Physics A-materials Science & Processing
    Vol. 112(2), pp. 463-467 
    article DOI  
    Abstract: We studied ordered arrays of magnetic nanoparticles (NPs) in a nonmagnetic matrix. The influence of annealing temperature and measurement geometry (varying angle between sample surface and external magnetic field direction) on magnetoresistance and coercive field values was established. Measurements were done on the Au(2 nm)/Cu(20 nm)/Fe3O4(NPs)/SiO2/Si system.
    BibTeX:
    @article{Nepijko2013,
      author = {Nepijko, S. A. and Elmers, H. J. and Schoenhense, G. and Demydenko, M. H. and Protsenko, S. I. and Kostyuk, D. M.},
      title = {Magnetoresistive properties of Fe3O4 nanoparticles embedded in a Cu matrix},
      journal = {Applied Physics A-materials Science & Processing},
      year = {2013},
      volume = {112},
      number = {2},
      pages = {463--467},
      doi = {http://dx.doi.org/10.1007/s00339-012-7434-0}
    }
    
    Nepijko, S.A., Fedchenko, O., Chernov, S.V. and Schoenhense, G. Growth and defect studies of CdTe particles 2013 Crystal Research and Technology
    Vol. 48(5), pp. 287-293 
    article DOI  
    Abstract: The paper reports the epitaxial growth of cadmium telluride (CdTe) particles by thermal deposition on cleaved planes of (001)NaCl and (001)KBr. Using high resolution transmission electron microscopy and electron diffraction it was shown that CdTe particles could have different orientation and phase (cubic or hexagonal) depending on the substrate temperature. Their most common defects are twins and stacking faults.
    BibTeX:
    @article{Nepijko2013b,
      author = {Nepijko, S. A. and Fedchenko, O. and Chernov, S. V. and Schoenhense, G.},
      title = {Growth and defect studies of CdTe particles},
      journal = {Crystal Research and Technology},
      year = {2013},
      volume = {48},
      number = {5},
      pages = {287--293},
      doi = {http://dx.doi.org/10.1002/crat.201200490}
    }
    
    Nepijko, S.A., Kostyuk, D.M., Protsenko, S.I., Schulze, W. and Schoenhense, G. Decoration of atomic steps on (001)NaCl cleavage face during deposition of preformed Ag clusters 2013 Applied Physics A-materials Science & Processing
    Vol. 111(1), pp. 237-242 
    article DOI  
    Abstract: Ag clusters obtained by the gas-aggregation technique were deposited on the cleavage face (001)NaCl. The average size of the nanoparticles was varied in the range from 0.2 to 10 nm and the temperature was varied from room temperature to 470 K. Owing to the mobility of the clusters on the substrate, they coalesced with formation of larger particles, decorating atomic cleavage steps on (001)NaCl already at room temperature. It was shown that the step decoration is possible only when the average size of the deposited clusters is commensurable with the height of the cleavage steps.
    BibTeX:
    @article{Nepijko2013a,
      author = {Nepijko, S. A. and Kostyuk, D. M. and Protsenko, S. I. and Schulze, W. and Schoenhense, G.},
      title = {Decoration of atomic steps on (001)NaCl cleavage face during deposition of preformed Ag clusters},
      journal = {Applied Physics A-materials Science & Processing},
      year = {2013},
      volume = {111},
      number = {1},
      pages = {237--242},
      doi = {http://dx.doi.org/10.1007/s00339-013-7575-9}
    }
    
    Nepijko, S.A., Petrov, A., Kondrakhova, D., Protsenko, I.Y., Elmers, H.J. and Schoenhense, G. Investigation of exchange bias effect of fine cobalt particles with oxidized surface 2013 Journal of Nanoparticle Research
    Vol. 15(5), pp. 1603 
    article DOI  
    Abstract: Phase characteristics of the partially oxidized cobalt particles were investigated. It is shown that the studied system consists of Co, CoO, and Co3O4 phases. The paper presents results for the magnetic characteristics of Co particles covered by a CoO shell. Magnetic measurements were performed at 77 K. It is shown that the shapes of the hysteresis loop of the investigated system are different for different cases of cooling, with and without applications of external magnetic field. Structural investigations were performed on single particles.
    BibTeX:
    @article{Nepijko2013c,
      author = {Nepijko, S. A. and Petrov, A. and Kondrakhova, D. and Protsenko, I. Yu and Elmers, H. J. and Schoenhense, G.},
      title = {Investigation of exchange bias effect of fine cobalt particles with oxidized surface},
      journal = {Journal of Nanoparticle Research},
      year = {2013},
      volume = {15},
      number = {5},
      pages = {1603},
      doi = {http://dx.doi.org/10.1007/s11051-013-1603-8}
    }
    
    Nepijko, S.A., Pylypenko, O.V., Odnodvorets, L.V., Kisker, E., Elmers, H.J. and Schoenhense, G. Quadratic magnetooptical effects in two-dimensional permalloy particles investigated by scanning X-ray microscopy 2013 Applied Physics A-materials Science & Processing
    Vol. 111(2), pp. 557-561 
    article DOI  
    Abstract: We have investigated the magnetization structure and magnetization curves of individual rectangularity shaped permalloy particles using scanning X-ray microscopy in the ultrasoft X-ray regime. Magnetic contrast originates from X-ray magnetic circular dichroism and from the transverse magnetooptical Kerr effect. We studied magnetization curves in dependence on the field direction for particles of different shapes and sizes. Adjacent particles cause a significant dipole interaction. Asymmetric magnetization loops indicate the presence of non-linear magnetooptical effects.
    BibTeX:
    @article{Nepijko2013d,
      author = {Nepijko, S. A. and Pylypenko, O. V. and Odnodvorets, L. V. and Kisker, E. and Elmers, H. J. and Schoenhense, G.},
      title = {Quadratic magnetooptical effects in two-dimensional permalloy particles investigated by scanning X-ray microscopy},
      journal = {Applied Physics A-materials Science & Processing},
      year = {2013},
      volume = {111},
      number = {2},
      pages = {557--561},
      doi = {http://dx.doi.org/10.1007/s00339-012-7257-z}
    }
    
    Tusche, C., Ellguth, M., Krasyuk, A., Winkelmann, A., Kutnyakhov, D., Lushchyk, P., Medjanik, K., Schoenhense, G. and Kirschner, J. Quantitative spin polarization analysis in photoelectron emission microscopy with an imaging spin filter 2013 Ultramicroscopy
    Vol. 130, pp. 70–76 
    article DOI  
    Abstract: Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectroscopic imaging of ultrathin magnetic Co films grown on Cu(100). The spin-filter, based on the spin-dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4 x 10(3) points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample. (C) 2013 Elsevier BY. All rights reserved.
    BibTeX:
    @article{Tusche2013,
      author = {Tusche, Christian and Ellguth, Martin and Krasyuk, Alexander and Winkelmann, Aimo and Kutnyakhov, Dmytro and Lushchyk, Pavel and Medjanik, Katerina and Schoenhense, Gerd and Kirschner, Juergen},
      title = {Quantitative spin polarization analysis in photoelectron emission microscopy with an imaging spin filter},
      journal = {Ultramicroscopy},
      year = {2013},
      volume = {130},
      pages = {70–76},
      doi = {http://dx.doi.org/10.1016/j.ultramic.2013.02.022}
    }
    
    Graivoronska, K.O., Klimenkov, M., Solonin, Y.M., Nepijko, S.A. and Schönhense, G. Detailed study of defects in thin fullerite films 2012 Crystal Research and Technology
    Vol. 47(12), pp. 1255-1268 
    article DOI  
    BibTeX:
    @article{Graivoronska2012,
      author = {Graivoronska, K. O. and Klimenkov, M. and Solonin, Yu. M. and Nepijko, S. A. and Schönhense, G.},
      title = {Detailed study of defects in thin fullerite films},
      journal = {Crystal Research and Technology},
      publisher = {Wiley-Blackwell},
      year = {2012},
      volume = {47},
      number = {12},
      pages = {1255-1268},
      doi = {http://dx.doi.org/10.1002/crat.201200304}
    }
    
    Hild, K., Schoenhense, G., Elmers, H.J., Nakagawa, T., Yokoyama, T., Tarafder, K. and Oppeneer, P.M. Dominance of the first excitation step for magnetic circular dichroism in near-threshold two-photon photoemission 2012 Physical Review B
    Vol. 85(1), pp. 014426 
    article DOI  
    Abstract: Magnetic circular dichroism (MCD) in near-threshold photoemission is measured for a perpendicularly magnetized Cs/Co/Pt(111) film with work function adjusted by Cs adsorption. For one-photon photoemission (1PPE) the MCD asymmetry is recorded at a fixed photon energy of h nu = 3.06 eV and varying work function Phi. The asymmetry shows a nonmonotonous behavior in dependence of the excess energy h nu-Phi with a maximum value of A(1PPE) = 6.2 % at Phi = 2.45 eV. The measurement explores the first excitation step of a former two-photon photoemission (2PPE) measurement with A(2PPE) = 8.4% demonstrating that in 2PPE from Co(111) the first excitation step is the dominant asymmetry-generating process. An energy-dependent measurement in 2PPE at reduced work function (Phi approximate to 3 eV) yields a constant asymmetry of about 17% in the photon energy range between h nu = 1.53-1.66 eV. It reveals that for Co(111) the involvement of a real intermediate state is crucial for enlarged MCD asymmetries. Both results are discussed in the framework of direct interband transitions in directions deviating from the direction of normal electron emission Gamma-L. The 1PPE measurement is in reasonable agreement with calculations on the basis of this model. This reveals that an ab initio calculation considering all directions of excitation with an additional restriction in energy due to the existence of the sample work function in the photoemission process adequately describes MCD asymmetries in near-threshold photoemission.
    BibTeX:
    @article{Hild2012,
      author = {Hild, K. and Schoenhense, G. and Elmers, H. J. and Nakagawa, T. and Yokoyama, T. and Tarafder, K. and Oppeneer, P. M.},
      title = {Dominance of the first excitation step for magnetic circular dichroism in near-threshold two-photon photoemission},
      journal = {Physical Review B},
      year = {2012},
      volume = {85},
      number = {1},
      pages = {014426},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.014426}
    }
    
    Kolbe, M., Chadov, S., Jorge, E.A., Schoenhense, G., Felser, C., Elmers, H.-J., Klaeui, M. and Jourdan, M. Test of band structure calculations for Heusler compounds by spin-resolved photoemission spectroscopy 2012 Phys. Rev. B
    Vol. 86(2), pp. 024422- 
    article DOI  
    Abstract: The electronic density of states of epitaxial thin films of the Heusler compound Co2MnGa is probed in situ by spin-resolved ultraviolet photoemission spectroscopy. The experiments reveal several characteristic features in the intensity spectrum and a clear Fermi edge signature. A high spin polarization of ≃ 55% at the Fermi edge is followed by a sign change at the binding energy of ≃0.8 eV. Corresponding calculations of the band structure and the photoemission spectrum were performed employing a spin-polarized relativistic Korringa-Kohn-Rostoker code. Good agreement between the experimental data and calculations was obtained, including dynamical correlation effects.

    ©2012 American Physical Society

    BibTeX:
    @article{Kolbe2012,
      author = {Kolbe, M. and Chadov, S. and Jorge, E. Arbelo and Schoenhense, G. and Felser, C. and Elmers, H.-J. and Klaeui, M. and Jourdan, M.},
      title = {Test of band structure calculations for Heusler compounds by spin-resolved photoemission spectroscopy},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {86},
      number = {2},
      pages = {024422--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.86.024422}
    }
    
    Medjanik, K., Chercka, D., Nagel, P., Merz, M., Schuppler, S., Baumgarten, M., Muellen, K., Nepijko, S.A., Elmers, H.-J., Schoenhense, G., Jeschke, H.O. and Valenti, R. Orbital-Resolved Partial Charge Transfer from the Methoxy Groups of Substituted Pyrenes in Complexes with Tetracyanoquinodimethane-A NEXAFS Study 2012 Journal of the American Chemical Society
    Vol. 134(10), pp. 4694-4699 
    article DOI  
    Abstract: It is demonstrated that the near-edge X-ray absorption fine structure (NEXAFS) provides a powerful local probe of functional groups in novel charge transfer (CT) compounds and their electronic properties. Microcrystals of tetra-/hexamethoxypyrene as donors with the strong acceptor tetracyano-p-quinodimethane (TMP/HMP-TCNQ) were grown by vapor diffusion. The oxygen and nitrogen K-edge spectra are spectroscopic fingerprints of the functional groups in the donor and acceptor moieties, respectively. The orbital selectivity of the NEXAFS pre-edge resonances allows us to precisely elucidate the participation of specific orbitals in the charge transfer process. Upon complex formation, the intensities of several resonances change substantially and a new resonance occurs in the oxygen K-edge spectrum. This gives evidence of a corresponding change of hybridization of specific orbitals in the functional groups of the donor (those derived from the frontier orbitals 2e and 6a(1) of the isolated methoxy group) and acceptor (orbitals b(3g), a(w), b(1g), and b(2w), all located at the cyano group) with pi*-orbitals of the ring systems. Along with this intensity effect, the resonance positions associated with the oxygen K-edge (donor) and nitrogen K-edge (acceptor) shift to higher and lower photon energies in the complex, respectively. A calculation based on density functional theory qualitatively explains the experimental results. NEXAFS measurements shine light on the action of the functional groups and elucidate charge transfer on a submolecular level.
    BibTeX:
    @article{Medjanik2012,
      author = {Medjanik, Katerina and Chercka, Dennis and Nagel, Peter and Merz, Michael and Schuppler, Stefan and Baumgarten, Martin and Muellen, Klaus and Nepijko, Sergej A. and Elmers, Hans-Joachim and Schoenhense, Gerd and Jeschke, Harald O. and Valenti, Roser},
      title = {Orbital-Resolved Partial Charge Transfer from the Methoxy Groups of Substituted Pyrenes in Complexes with Tetracyanoquinodimethane-A NEXAFS Study},
      journal = {Journal of the American Chemical Society},
      year = {2012},
      volume = {134},
      number = {10},
      pages = {4694--4699},
      doi = {http://dx.doi.org/10.1021/ja2100802}
    }
    
    Medjanik, K., Gloskovskii, A., Kutnyakhov, D., Felser, C., Chercka, D., Baumgarten, M., Muellen, K. and Schoenhense, G. Charge transfer in the novel donor-acceptor complexes tetra- and hexamethoxypyrene with tetracyanoquinodimethane studied by HAXPES 2012 Journal of Electron Spectroscopy and Related Phenomena
    Vol. 185(3-4), pp. 77-84 
    article DOI  
    Abstract: The effect of charge transfer (CT) in complexes of the donors tetra- and hexamethoxyprene (TMP and HMP) with the classical acceptor tetracyanoquinodimethane (TCNQ) was studied using hard X-ray photoemission (HAXPES). Microcrystals of the complex were grown via vapour diffusion from donor-acceptor mixtures. The bulk sensitivity of HAXPES at a photon energy of 6 key completely eliminates the problem of surface contamination for such delicate organic materials grown from solution. The donor molecules were produced using a novel synthesis route functionalizing polycyclic aromatic hydrocarbons at their periphery. For comparison, spectra were also taken from thin-film samples of the same compounds produced via co-deposition in UHV. Upon complex formation, the oxygen 1s core-level spectra (being a fingerprint of the methoxy-group of the donors) change from the single-line spectrum of pure HMP (TMP) to a spectrum with two distinct lines shifted by 1.4 (0.9) eV and 2.6 (2.3) eV with respect to the position of the oxygen 1s line of the pure donors. The nitrogen 1s spectra (being a fingerprint of the cyano-group in the acceptor) show two peaks as well with a corresponding shift of 0.9 eV and 2.0 eV in comparison with the leading line of pure TCNQ in opposite direction to the oxygen is spectra. These values are substantially larger than shifts in near edge X-ray absorption fine structure (NEXAFS) and ultraviolet photoelectron spectroscopy (UPS) spectra of the same complexes. The changes in the spectra are discussed in terms of the CT in the complexes. Residues of pure donor and acceptor materials in the microcrystal fractions of the complexes are evident from the presence of non-shifted lines. Peak-area analysis reveals that charge is transferred to a fraction of 60% of the molecules in the complexes. (C) 2012 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Medjanik2012a,
      author = {Medjanik, K. and Gloskovskii, A. and Kutnyakhov, D. and Felser, C. and Chercka, D. and Baumgarten, M. and Muellen, K. and Schoenhense, G.},
      title = {Charge transfer in the novel donor-acceptor complexes tetra- and hexamethoxypyrene with tetracyanoquinodimethane studied by HAXPES},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      year = {2012},
      volume = {185},
      number = {3-4},
      pages = {77--84},
      doi = {http://dx.doi.org/10.1016/j.elspec.2012.02.002}
    }
    
    Nepijko, S.A., Kutnyakhov, D., Protsenko, I.E., Elmers, H.J. and Schoenhense, G. Structure and magnetic properties of one-dimensional chains of ferromagnetic nanoparticles 2012 Applied Physics A-materials Science & Processing
    Vol. 109(3), pp. 699-702 
    article DOI  
    Abstract: One-dimensional chains and rings of equally sized ferromagnetic nanoparticles have been investigated using magnetic force microscopy. The one-dimensional structure of the Ni nanoparticles forms by self-assembled growth on a stepped surface of highly oriented pyrolytic graphite (HOPG). The nanoparticles show single-domain magnetization states with the magnetization aligned along the chain.
    BibTeX:
    @article{Nepijko2012,
      author = {Nepijko, S. A. and Kutnyakhov, D. and Protsenko, I. E. and Elmers, H. J. and Schoenhense, G.},
      title = {Structure and magnetic properties of one-dimensional chains of ferromagnetic nanoparticles},
      journal = {Applied Physics A-materials Science & Processing},
      year = {2012},
      volume = {109},
      number = {3},
      pages = {699--702},
      doi = {http://dx.doi.org/10.1007/s00339-012-7103-3}
    }
    
    Nepijko, S.A., Kutnyakhov, D., Protsenko, I.E., Elmers, H.J. and Schönhense, G. Structure and magnetic properties of one-dimensional chains of ferromagnetic nanoparticles 2012 Applied Physics A
    Vol. 109(3), pp. 699¬タモ702 
    article DOI  
    BibTeX:
    @article{Nepijko2012a,
      author = {Nepijko, S. A. and Kutnyakhov, D. and Protsenko, I. E. and Elmers, H. J. and Schönhense, G.},
      title = {Structure and magnetic properties of one-dimensional chains of ferromagnetic nanoparticles},
      journal = {Applied Physics A},
      publisher = {Springer Science + Business Media},
      year = {2012},
      volume = {109},
      number = {3},
      pages = {699¬タモ702},
      doi = {http://dx.doi.org/10.1007/s00339-012-7103-3}
    }
    
    Schertz, F., Schmelzeisen, M., Kreiter, M., E., H.-J. and Schoenhense, G. Field Emission of Electrons Generated by the Near Field of Strongly Coupled Plasmons 2012 Phys. Rev. Lett.
    Vol. 108(23), pp. 237602- 
    article DOI  
    Abstract: Field emission of electrons is generated solely by the ultrastrong near-field of strongly coupled plasmons without the help of a noticeable dc field. Strongly coupled plasmons are excited at Au nanoparticles in subnanometer distance to a Au film by femtosecond laser pulses. Field-emitted electrons from individual nanoparticles are detected by means of photoelectron emission microscopy and spectroscopy. The dependence of total electron yield and kinetic energy on the laser power proves that field emission is the underlying emission process. We derive a dynamic version of the Fowler–Nordheim equation that yields perfect agreement with the experiment.
    BibTeX:
    @article{Schertz2012a,
      author = {Schertz, F. and Schmelzeisen, M. and Kreiter, M. and E., H.-J. and Schoenhense, G.},
      title = {Field Emission of Electrons Generated by the Near Field of Strongly Coupled Plasmons},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {2012},
      volume = {108},
      number = {23},
      pages = {237602--},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.108.237602}
    }
    
    Schertz, F., Schmelzeisen, M., Mohammadi, R., Kreiter, M., Elmers, H.-J. and Schoenhense, G. Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes 2012 Nano Lett.
    Vol. 12(4), pp. 1885-1890 
    article DOI  
    Abstract: Strongly coupled plasmons in a system of individual gold nanoparticles placed at subnanometer distance to a gold film (nanoparticle-on-plane, NPOP) are investigated using two complementary single particle spectroscopy techniques. Optical scattering spectroscopy exclusively detects plasmon modes that couple to the far field via their dipole moment (bright modes). By using photoemission electron microscopy (PEEM), we detect in the identical NPOPs near-field modes that do not couple to the scattered far field (dark modes) and are characterized by a strongly enhanced nonlinear electron emission process. To our knowledge, this is the first time that both far- and near-field spectroscopy are carried out for identical individual nanostructures interacting via a subnanometer gap. Strongly resonant electron emission occurs at excitation wavelengths far off-resonant in the scattering spectra.
    BibTeX:
    @article{Schertz2012,
      author = {Schertz, F and Schmelzeisen, M and Mohammadi, R and Kreiter, M and Elmers, H-J and Schoenhense, G},
      title = {Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes},
      journal = {Nano Lett.},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {12},
      number = {4},
      pages = {1885--1890},
      doi = {http://dx.doi.org/10.1021/nl204277y}
    }
    
    Schwander, D., Berg, T., Ott, U., Schoenhense, G. and Palme, H. Formation of refractory metal alloys and their occurrence in CAIs. 2012 Meteoritics & Planetary Science
    Vol. 47, pp. A348-A348 
    article  
    BibTeX:
    @article{Schwander2012,
      author = {Schwander, D. and Berg, T. and Ott, U. and Schoenhense, G. and Palme, H.},
      title = {Formation of refractory metal alloys and their occurrence in CAIs.},
      journal = {Meteoritics & Planetary Science},
      year = {2012},
      volume = {47},
      pages = {A348-A348}
    }
    
    Stryganyuk, G., Kozina, X., Fecher, G.H., Ouardi, S., Chadov, S., Felser, C., Schoenhense, G., Lushchyk, P., Oelsner, A., Bernhard, P., Ikenaga, E., Sugiyama, T., Sukegawa, H., Wen, Z., Inomata, K. and Kobayashi, K. Spin Polarimetry and Magnetic Dichroism on a Buried Magnetic Layer Using Hard X-ray Photoelectron Spectroscopy 2012 Japanese Journal of Applied Physics
    Vol. 51(1), pp. 016602 
    article DOI  
    Abstract: The spin-resolved electronic structure of buried magnetic layers is studied by hard X-ray photoelectron spectroscopy (HAXPES) using a spin polarimeter in combination with a high-energy hemispherical electron analyzer at the high-brilliance BL47XU beamline (SPring-8, Japan). Spin-resolved photoelectron spectra are analyzed in comparison with the results of magnetic linear and circular dichroism in photoelectron emission in the case of buried Co2FeAl0.5Si0.5 layers. The relatively large inelastic mean free path (up to 20 nm) of fast photoelectrons enables us to extend the HAXPES technique with electron-spin polarimetry and to develop spin analysis techniques for buried magnetic multilayers and interfaces. (C) 2012 The Japan Society of Applied Physics
    BibTeX:
    @article{Stryganyuk2012,
      author = {Stryganyuk, Gregory and Kozina, Xeniya and Fecher, Gerhard H. and Ouardi, Siham and Chadov, Stanislav and Felser, Claudia and Schoenhense, Gerd and Lushchyk, Pavel and Oelsner, Andreas and Bernhard, Pasqual and Ikenaga, Eiji and Sugiyama, Takeharu and Sukegawa, Hiroaki and Wen, Zhenchao and Inomata, Koichiro and Kobayashi, Keisuke},
      title = {Spin Polarimetry and Magnetic Dichroism on a Buried Magnetic Layer Using Hard X-ray Photoelectron Spectroscopy},
      journal = {Japanese Journal of Applied Physics},
      year = {2012},
      volume = {51},
      number = {1},
      pages = {016602},
      doi = {http://dx.doi.org/10.1143/JJAP.51.016602}
    }
    
    Hahn, M., Schönhense, G., Jorge, E. and Jourdan, M. Significant spin polarization of Co2MnGa Heusler thin films on MgO (100) measured by ultraviolet photoemission spectroscopy 2011 Applied Physics Letters
    Vol. 98(23), pp. 232503-232503 
    article DOI  
    Abstract: The spin dependent valence band structure of the Heusler compound Co2MnGa grown on MgO(100) is investigated by spin resolved ultraviolet photoemission spectroscopy (SRUPS). Using a vacuum suitcase, epitaxial thin film samples are transferred from a deposition chamber into an SRUPS chamber with a highly efficient spin detector. The transport results only in weak oxidation of the moderately reactive compound Co2MnGa. A spin polarization of 34% is obtained at the Fermi energy. The energy dependence of the spin polarization including a sign change at E-EF=-0.6 eV is in good agreement with theoretical predictions of the bulk properties of the Heusler compound.
    BibTeX:
    @article{Hahn2011,
      author = {Hahn, M. and Schönhense, G. and Jorge, E.A. and Jourdan, M.},
      title = {Significant spin polarization of Co2MnGa Heusler thin films on MgO (100) measured by ultraviolet photoemission spectroscopy},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2011},
      volume = {98},
      number = {23},
      pages = {232503--232503},
      doi = {http://dx.doi.org/10.1063/1.3597315}
    }
    
    Jourdan, M., Große-Schulte, F., Hahn, M. and Schönhense, G. Spectroscopy of the electronic states of the Heusler compounds Co 2 FeAl and Co 2 Cr 0.6 Fe 0.4 Al and the influence of oxidation 2011 Journal of Physics D: Applied Physics
    Vol. 44(15), pp. 155001 
    article DOI  
    Abstract: The band structures of the Heusler compounds Co 2 Cr 0.6 Fe 0.4 Al and Co 2 FeAl were investigated in situ by angle-resolved ultraviolet photoemission spectroscopy. The samples were prepared by a sputtering process optimized for tunnelling junction preparation, the photoemission process in the normal direction of the (0 0 1)-oriented thin films was excited by a helium gas discharge lamp ( h v = 21.2 eV and h v = 40.8 eV). The spectra of clean samples are compared with calculations of the total and partial bulk density of states and are evaluated within the three-step model of photoemission. Basic agreement with theoretical predictions of the bulk band structure is concluded. At oxygen exposures of the thin films of only 1 Langmuir a chemisorption phase with significant changes in the valence-band spectrum near the Fermi energy is observed. At 10 L oxygen the spectra are indicative of an oxide within the UPS probing depth.
    BibTeX:
    @article{Jourdan2011,
      author = {Martin Jourdan and Fabian Große-Schulte and Michaela Hahn and Gerd Schönhense},
      title = {Spectroscopy of the electronic states of the Heusler compounds Co 2 FeAl and Co 2 Cr 0.6 Fe 0.4 Al and the influence of oxidation},
      journal = {Journal of Physics D: Applied Physics},
      year = {2011},
      volume = {44},
      number = {15},
      pages = {155001},
      doi = {http://dx.doi.org/10.1088/0022-3727/44/15/155001}
    }
    
    Kolbe, M., Lushchyk, P., Petereit, B., Elmers, H.J., Schönhense, G., Oelsner, A., Tusche, C. and Kirschner, J. Highly Efficient Multichannel Spin-Polarization Detection 2011 Phys. Rev. Lett.
    Vol. 107(20), pp. 207601- 
    article DOI  
    Abstract: Since the original work by Mott, the low efficiency of electron spin polarimeters, remaining orders of magnitude behind optical polarimeters, has prohibited many fundamental experiments. Here we report a solution to this problem using a novel concept of multichannel spin-polarization analysis that provides a stunning increase in efficiency by 4 orders of magnitude. This improvement was demonstrated in a setup using a hemispherical electron energy analyzer. An imaging setup proved the principal capability of resolving more than 105 data points in parallel.
    BibTeX:
    @article{Kolbe2011,
      author = {Kolbe, M. and Lushchyk, P. and Petereit, B. and Elmers, H. J. and Schönhense, G and Oelsner, A. and Tusche, C. and Kirschner, J.},
      title = {Highly Efficient Multichannel Spin-Polarization Detection},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {2011},
      volume = {107},
      number = {20},
      pages = {207601--},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.107.207601}
    }
    
    Kozina, X., Fecher, G.H., Stryganyuk, G., Ouardi, S., Balke, B., Felser, C., Schönhense, G., Ikenaga, E., Sugiyama, T., Kawamura, N. and et al. Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers 2011 Phys. Rev. B
    Vol. 84(5), pp. 054449 
    article DOI  
    BibTeX:
    @article{Kozina2011a,
      author = {Kozina, Xeniya and Fecher, Gerhard H. and Stryganyuk, Gregory and Ouardi, Siham and Balke, Benjamin and Felser, Claudia and Schönhense, Gerd and Ikenaga, Eiji and Sugiyama, Takeharu and Kawamura, Naomi and et al.},
      title = {Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society (APS)},
      year = {2011},
      volume = {84},
      number = {5},
      pages = {054449},
      doi = {http://dx.doi.org/10.1103/physrevb.84.054449}
    }
    
    Kozina, X., Fecher, G.H., Stryganyuk, G., Ouardi, S., Balke, B., Felser, C., Schönhense, G., Ikenaga, E., Sugiyama, T., Kawamura, N., Suzuki, M., Taira, T., Uemura, T., Yamamoto, M., Sukegawa, H., Wang, W., Inomata, K. and Kobayashi, K. Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers 2011 Phys. Rev. B
    Vol. 84(5), pp. 054449- 
    article DOI  
    Abstract: This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard x-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co2FeAl layer buried beneath the IrMn layer. A pronounced magnetic dichroism is found in the Co and Fe 2p states of both materials. The localization of the magnetic moments at the Fe site conditioning the peculiar characteristics of the Co2FeAl Heusler compound, predicted to be a half-metallic ferromagnet, is revealed from the magnetic dichroism detected in the Fe 2p states.

    ©2011 American Physical Society

    BibTeX:
    @article{Kozina2011,
      author = {X. Kozina and G. H. Fecher and G. Stryganyuk and S. Ouardi and B. Balke and C. Felser and G. Schönhense and E. Ikenaga and T. Sugiyama and N. Kawamura and M. Suzuki and T. Taira and T. Uemura and M. Yamamoto and H. Sukegawa and W. Wang and K. Inomata and K. Kobayashi},
      title = {Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2011},
      volume = {84},
      number = {5},
      pages = {054449--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.84.054449}
    }
    
    Naghavi, S., Gruhn, T., Alijani, V., Fecher, G., Felser, C., Medjanik, K., Kutnyakhov, D., Nepijko, S., Schonhense, G., Rieger, R., Baumgarten, M. and Müllen, K. Theoretical study of new acceptor and donor molecules based on polycyclic aromatic hydrocarbons 2011 Journal of Molecular Spectroscopy
    Vol. 265(2), pp. 95-101 
    article DOI  
    Abstract: Functionalized polycyclic aromatic hydrocarbons (PAHs) are an interesting class of molecules in which the electronic state of the graphene-like hydrocarbon part is tuned by the functional group. Searching for new types of donor and acceptor molecules, a set of new PAHs has recently been investigated experimentally using ultraviolet photoelectron spectroscopy (UPS). In this work, the electronic structure of the PAHs is studied theoretically with the help of B3LYP hybrid density functionals. Using the [Delta]SCF method, electron binding energies have been determined which affirm, specify and complement the UPS data. Symmetry properties of molecular orbitals are analyzed for a categorization and an estimate of the related signal strength. While [sigma]-like orbitals are difficult to detect in UPS spectra of condensed film, calculation provides a detailed insight into the hidden parts of the electronic structure of donor and acceptor molecules. In addition, a diffuse basis set (6-311++G**) was used to calculate electron affinity and LUMO eigenvalues. The calculated electron affinity (EA) provides a classification of the donor/acceptor properties of the studied molecules. Coronene-hexaone shows a high EA, comparable to TCNQ, which is a well-known classical acceptor. Calculated HOMO-LUMO gaps using the related eigenvalues have a good agreement with the experimental lowest excitation energies. TD-DFT also accurately predicts the measured optical gap.
    BibTeX:
    @article{Naghavi2011,
      author = {Naghavi, S.S. and Gruhn, T. and Alijani, V. and Fecher, G.H. and Felser, C. and Medjanik, K. and Kutnyakhov, D. and Nepijko, S.A. and Schonhense, G. and Rieger, R. and Baumgarten, M. and Müllen, K.},
      title = {Theoretical study of new acceptor and donor molecules based on polycyclic aromatic hydrocarbons},
      journal = {Journal of Molecular Spectroscopy},
      year = {2011},
      volume = {265},
      number = {2},
      pages = {95--101},
      doi = {http://dx.doi.org/10.1016/j.jms.2010.12.004}
    }
    
    Schertz, F., Kutnyakhov, D., Schuppler, S., Nagel, P., Nepijko, S. and Schönhense, G. Measurement of object height in emission electron microscopy 2011 Applied Physics A: Materials Science & Processing
    Vol. 102(2), pp. 253-258 
    article DOI  
    Abstract: The possibility of measuring the height of an object in emission electron microscopy (EEM) is investigated. If the specimen is characterized by an equipotential surface with the relief h(x,y), the image is equivalent to a specimen with an ideal flat surface and a corresponding distribution of the electric potential φ(x,y)=−E ext h(x,y). As a consequence of the interaction with the microfields grad φ(x,y), the trajectories of electrons forming the image become deformed, which leads to characteristic image distortion. From EEM, images obtained at different voltages of the extractor V ext,φ(x,y) can be derived and thereby h(x,y) is reconstructed. If the surface of the specimen is characterized both by a distribution of the potential and in addition by a relief h(x,y), then for the reconstruction one needs an additional EEM image taken at a different voltage of the extractor. The maximal sensitivity to microfields/relief is exploited when using the electron microscope in the mirror operation mode. We illustrate the performance of the method by means of a test pattern of Au on Si. For quantitative comparison, the same structure was investigated by atomic force microscope.
    BibTeX:
    @article{Schertz2011,
      author = {Schertz, F. and Kutnyakhov, D. and Schuppler, S. and Nagel, P. and Nepijko, S. and Schönhense, G.},
      title = {Measurement of object height in emission electron microscopy},
      journal = {Applied Physics A: Materials Science & Processing},
      publisher = {Springer Berlin / Heidelberg},
      year = {2011},
      volume = {102},
      number = {2},
      pages = {253--258},
      doi = {http://dx.doi.org/10.1007/s00339-010-5998-0}
    }
    
    Tusche, C., Ellguth, M., Ünal, A., Chiang, C., Winkelmann, A., Krasyuk, A., Hahn, M., Schöhense, G. and Kirschner, J. Spin resolved photoelectron microscopy using a two-dimensional spin-polarizing electron mirror 2011 Applied Physics Letters
    Vol. 99, pp. 032505 
    article DOI  
    Abstract: We report on an imaging spin-filter for electrons. The specular reflection of low-energy electrons at the surface of a tungsten single crystal is used to project a spin-filtered two-dimensional image onto a position sensitive detector. Spin-filtering is based on the spin-dependent reflectivity of electrons due to spin-orbit coupling in the scattering target, while a two-dimensional field of view, encoded in the angle of incidence, is conserved in the outgoing beam. We characterize the efficiency of the spin-filter by recording photoelectron emission microscopy images of the magnetic domain structure of 8 monolayers cobalt grown on copper (100).
    BibTeX:
    @article{Tusche2011,
      author = {Tusche, C. and Ellguth, M. and Ünal, AA and Chiang, C.T. and Winkelmann, A. and Krasyuk, A. and Hahn, M. and Schöhense, G. and Kirschner, J.},
      title = {Spin resolved photoelectron microscopy using a two-dimensional spin-polarizing electron mirror},
      journal = {Applied Physics Letters},
      year = {2011},
      volume = {99},
      pages = {032505},
      doi = {http://dx.doi.org/10.1063/1.3611648}
    }
    
    Buluy, O., Nepijko, S., Reshetnyak, V., Ouskova, E., Zadorozhnii, V., Leonhardt, A., Ritschel, M., Schönhense, G. & Reznikov, Y. Magnetic sensitivity of a dispersion of aggregated ferromagnetic carbon nanotubes in liquid crystals 2010 Soft Matter
    Vol. 7, pp. 644-649 
    article DOI  
    BibTeX:
    @article{Buluy2010,
      author = {Buluy, O. and Nepijko, S. and Reshetnyak, V. and Ouskova, E. and Zadorozhnii, V. and Leonhardt, A. and Ritschel, M. and Schönhense, G. and Reznikov, Y.},
      title = {Magnetic sensitivity of a dispersion of aggregated ferromagnetic carbon nanotubes in liquid crystals},
      journal = {Soft Matter},
      publisher = {The Royal Society of Chemistry},
      year = {2010},
      volume = {7},
      pages = {644-649},
      doi = {http://dx.doi.org/10.1039/C0SM00131G}
    }
    
    Elmers, H. & Schönhense, G. Ferromagnetism at the summit: A perspective on: "Spin polarized field emission from Fe and co-coated W tips" by Y.R. Niu and M.S. Altman 2010 Surface Science
    Vol. 604(11-12), pp. 1060-1061 
    article DOI  
    BibTeX:
    @article{Elmers2010,
      author = {Elmers, H.J. and Schönhense, G.},
      title = {Ferromagnetism at the summit: A perspective on: "Spin polarized field emission from Fe and co-coated W tips" by Y.R. Niu and M.S. Altman},
      journal = {Surface Science},
      year = {2010},
      volume = {604},
      number = {11-12},
      pages = {1060--1061},
      doi = {http://dx.doi.org/10.1016/j.susc.2010.03.007}
    }
    
    Gloskovskii, A., Valdaitsev, D., Viduta, L., Nepijko, S.A. & Schönhense, G. Investigation of the local electron emission from current-carrying silver nanoparticle films by an emission electron microscope 2010 Thin Solid Films
    Vol. 518(14), pp. 4030-4034 
    article DOI  
    Abstract: Emission electron microscopy was used to study the electron emission observed under the passage of a tunnel current through a silver nanoparticle film when a voltage is applied to it. The electron emission originates from separate emission centers emitting photons as well. The electron emission centers are visualized as separate spots in an emission electron microscope. A deformation of shape and size of these spots was studied at various applied voltages. It enables the energy spread of electrons emitted from an individual emission center or at least the width of its most intensive part E as well as the magnitude of electric field E near this center to be estimated. It has been shown that E comprises 0.5-0.6 eV, and E<<10(7) V/cm. The latter result means that the electron emission is not the field emission. (C) 2010 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Gloskovskii2010,
      author = {Gloskovskii, A. and Valdaitsev, D. and Viduta, L. and Nepijko, S. A. and Schönhense, G.},
      title = {Investigation of the local electron emission from current-carrying silver nanoparticle films by an emission electron microscope},
      journal = {Thin Solid Films},
      year = {2010},
      volume = {518},
      number = {14},
      pages = {4030--4034},
      doi = {http://dx.doi.org/10.1016/j.tsf.2010.01.021}
    }
    
    Hild, K., Schönhense, G., Elmers, H.J., Nakagawa, T., Yokoyama, T., Tarafder, K. & Oppeneer, P.M. Energy- and angle-dependent threshold photoemission magnetic circular dichroism from an ultrathin Co/Pt(111) film 2010 Physical Review B
    Vol. 82(19), pp. 195430 
    article DOI  
    Abstract: Threshold photoemission magnetic circular dichroism (TPMCD) in one-photon photoemission (1PPE) and two-photon photoemission (2PPE) is measured at an ultrathin Co film grown on Pt(111). Energy-dependent measurements reveal maximum asymmetries directly at the photoemission threshold (1.90% for 1PPE and 11.7% for 2PPE) which weakly decrease with increasing photon energy. The measured TPMCD asymmetries are discussed in two excitation models on the basis of spin-resolved band-structure calculations. For the model of direct band-to-band transitions in other k directions than the direction of observation (Gamma-L) ab initio calculations for 1PPE and 2PPE are performed. The theory is in reasonable agreement with the measured TPMCD responses. An explanation of the large 2PPE TPMCD signal is provided in terms of specific interband excitations within the first excitation step. In the case of 2PPE angle-dependent measurements reveal a continuous drop of the asymmetry with increasing angle of incidence that agrees perfectly well with a calculation using the Fresnel equations. For 1PPE a deviation from the Fresnel-field approximation is obvious.
    BibTeX:
    @article{Hild2010,
      author = {Hild, K. and Schönhense, G. and Elmers, H. J. and Nakagawa, T. and Yokoyama, T. and Tarafder, K. and Oppeneer, P. M.},
      title = {Energy- and angle-dependent threshold photoemission magnetic circular dichroism from an ultrathin Co/Pt(111) film},
      journal = {Physical Review B},
      year = {2010},
      volume = {82},
      number = {19},
      pages = {195430},
      doi = {http://dx.doi.org/10.1103/PhysRevB.82.195430}
    }
    
    Medjanik, K., Kutnyakhov, D., Nepijko, S.A., Schönhense, G., Naghavi, S., Alijani, V., Felser, C., Koch, N., Rieger, R., Baumgarten, M. & Mullen, K. Electronic structure of large disc-type donors and acceptors. 2010 Phys Chem Chem Phys
    Vol. 12(26), pp. 7184-93 
    article DOI  
    Abstract: Searching for new pi-conjugated charge-transfer systems, the electronic structure of a new acceptor-donor pair derived from coronene (C(24)H(12)) was investigated by ultraviolet photoelectron spectroscopy (UPS). The acceptor coronene-hexaone (C(24)H(6)O(6), in the following abbreviated as COHON) and the donor hexamethoxycoronene (C(30)H(24)O(6), abbreviated as HMC) were adsorbed as pure and mixed phases on gold substrates. At low coverage, COHON adsorption leads to the appearance of a charge-transfer induced interface state 1.75 eV below the Fermi energy. At multilayer coverage the photoemission intensity of the interface state drops and the valence spectrum of neutral COHON appears. The sample work function decreases from 5.3 eV (clean Au) to 4.8 eV (monolayer) followed by an increase to 5.6 eV (multilayer). The formation of a significant interface dipole due to charge-transfer at the metal-organic interface is possibly accompanied by a change in molecular orientation. HMC on Au exhibits no interface state and the sample work function decreases monotonically to ca. 4.8 eV (multilayer). The UPS spectra of individual donor and acceptor multilayers show good agreement with density functional theory modeling. In donor/acceptor mixed films the photoemission signal of the donor (acceptor) shifts to higher (lower) binding energy. This trend is predicted by the calculation and is anticipated when charge is transferred from donor to acceptor. We propose that mixed films of COHON and HMC constitute a weak charge-transfer system.
    BibTeX:
    @article{Medjanik2010,
      author = {Medjanik, K. and Kutnyakhov, D. and Nepijko, S. A. and Schönhense, G. and Naghavi, S. and Alijani, V. and Felser, C. and Koch, N. and Rieger, R. and Baumgarten, M. and Mullen, K.},
      title = {Electronic structure of large disc-type donors and acceptors.},
      journal = {Phys Chem Chem Phys},
      year = {2010},
      volume = {12},
      number = {26},
      pages = {7184--93},
      doi = {http://dx.doi.org/10.1039/B926999A}
    }
    
    Medjanik, K., Perkert, S., Naghavi, S., Rudloff, M., Solovyeva, V., Chercka, D., Huth, M., Nepijko, S.A., Methfessel, T., Felser, C., Baumgarten, M., Müllen, K., Elmers, H.J. & Schönhense, G. Formation of an intermolecular charge-transfer compound in UHV codeposited tetramethoxypyrene and tetracyanoquinodimethane 2010 Physical Review B
    Vol. 82(24), pp. 245419/1-9 
    article DOI  
    Abstract: Ultrahigh vacuum (UHV)-deposited films of the mixed phase of tetramethoxypyrene and tetracyanoquinodimethane (TMP1-TCNQ(1)) on gold have been studied using ultraviolet photoelectron spectroscopy (UPS), x-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning tunneling spectroscopy (STS). The formation of an intermolecular charge-transfer (CT) compound is evident from the appearance of new reflexes in XRD (d(1)=0.894 nm and d(2)=0.677 nm). A softening of the CN stretching vibration (redshift by 7 cm(-1)) of TCNQ is visible in the IR spectra, being indicative of a CT on the order of 0.3e from TMP to TCNQ in the complex. Characteristic shifts in the electronic level positions occur in UPS and STS that are in reasonable agreement with the prediction of density-functional theory (DFT) calculations (GAUSSIAN03 with hybrid functional B3LYP). STS reveals a highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of the CT complex of about 1.25 eV being much smaller than the gaps (>3.0 eV) of the pure moieties. The electron-injection and hole-injection barriers are 0.3 eV and 0.5 eV, respectively. Systematic differences in the positions of the HOMOs determined by UPS and STS are discussed in terms of the different information content of the two methods.
    BibTeX:
    @article{Medjanik2010a,
      author = {Medjanik, K. and Perkert, S. and Naghavi, S. and Rudloff, M. and Solovyeva, V. and Chercka, D. and Huth, M. and Nepijko, S. A. and Methfessel, T. and Felser, C. and Baumgarten, M. and Müllen, K. and Elmers, H. J. and Schönhense, G.},
      title = {Formation of an intermolecular charge-transfer compound in UHV codeposited tetramethoxypyrene and tetracyanoquinodimethane},
      journal = {Physical Review B},
      year = {2010},
      volume = {82},
      number = {24},
      pages = {245419/1-9},
      doi = {http://dx.doi.org/10.1103/PhysRevB.82.245419}
    }
    
    Nepijko, S.A. & Schönhense, G. Measurement of potential distribution function on object surface by using an electron microscope in the mirror operation mode 2010 Journal of Microscopy-oxford
    Vol. 238(1), pp. 90-94 
    article DOI  
    Abstract: The quantitative theory of image contrast in an electron microscope in the mirror operation mode is given in this paper. This theory permits us to calculate the potential distribution on the object surface from the current density distribution on the microscope screen. The potential distribution results in image formation on the screen. Local electric fields existing on the object surface lead to a perturbation of electron trajectories above the object and to a redistribution of the current density on the screen, causing image contrast. Using the quantitative correlation between these fields and the function of current density distribution on the screen, it is possible to calculate the magnitude of these microfields as well. As illustration, a measured potential distribution on an object surface with spiral structures of adsorbates was analysed. These structures are formed during reaction of CO oxidation on Pt(110). The value of the measured contact potential difference comprised a few hundredths of volt.
    BibTeX:
    @article{Nepijko2010,
      author = {Nepijko, S. A. and Schönhense, G.},
      title = {Measurement of potential distribution function on object surface by using an electron microscope in the mirror operation mode},
      journal = {Journal of Microscopy-oxford},
      year = {2010},
      volume = {238},
      number = {1},
      pages = {90--94},
      doi = {http://dx.doi.org/10.1111/j.1365-2818.2009.03340.x}
    }
    
    Oelsner, A., Rohmer, M., Schneider, C., Bayer, D., Schönhense, G. & Aeschlimann, M. Time- and energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations 2010 Journal of Electron Spectroscopy and Related Phenomena
    Vol. 178, pp. 317-330 
    article DOI  
    Abstract: The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for real-time spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer Or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump-probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4D imaging (x, y, Delta t, E-kin) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction. By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108 ps absolute and 13.5 ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time-resolved PEEM technique enables to display evolutions of spatially resolved (<25 nm) and temporal sliced images life on any modern computer. The method allows dynamics investigations of variable electrical, magnetic, and optical near fields at surfaces and great prospects in dynamical adaptive photoelectron optics. For dynamical processes in the ps time scale such as magnetic domain wall movements, the time resolution of the delay line detectors even allows to be used directly for real-time experiments as well. (C) 2009 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Oelsner2010,
      author = {Oelsner, A. and Rohmer, M. and Schneider, C. and Bayer, D. and Schönhense, G. and Aeschlimann, M.},
      title = {Time- and energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      year = {2010},
      volume = {178},
      pages = {317--330},
      doi = {http://dx.doi.org/10.1016/j.elspec.2009.10.008}
    }
    
    Panzer, D., Beck, C., Hahn, M., Maul, J., Schönhense, G., Decker, H. & Aziz, E.F. Water Influences on the Copper Active Site in Hemocyanin 2010 The Journal of Physical Chemistry Letters
    Vol. 1(10), pp. 1642-1647 
    article DOI  
    Abstract: Active metal sites play a key role in the biochemistry of oxygen transport by hemocyanins. Observing the changes in the local electronic structure of the copper sites upon oxygenation is thus essential for understanding their biological functionality. Here, direct access to the electronic structure of the active copper sites in hemocyanin is achieved via L-edge X-ray absorption spectroscopy under physiological conditions. We compare the deoxygenated and the oxygenated states of native hemocyanin and find evidence that the oxygenation does not simply switch the copper valence state between Cu I and Cu II, as assumed classically. In the deoxygenated state, water molecules can enter the active site and keep the copper atoms partially oxidized. The role of water in this process has never been revealed before for lack of L-edge spectroscopy on copper in solution. Besides providing a more detailed electronic picture for the oxygenation process, this study opens a new chapter in investigating the function of proteins under in-vivo-like conditions.
    BibTeX:
    @article{Panzer2010,
      author = {Panzer, Daniel and Beck, Christian and Hahn, Michaela and Maul, Jochen and Scho¨nhense, Gerd and Decker, Heinz and Aziz, Emad F.},
      title = {Water Influences on the Copper Active Site in Hemocyanin},
      journal = {The Journal of Physical Chemistry Letters},
      publisher = {American Chemical Society},
      year = {2010},
      volume = {1},
      number = {10},
      pages = {1642--1647},
      doi = {http://dx.doi.org/10.1021/jz100313q}
    }
    
    Basit, L., Nepijko, S., Shukoor, I., Ksenofontov, V., Klimenkov, M., Fecher, G., Schönhense, G., Tremel, W. & Felser, C. Structure and magnetic properties of iron-platinum particles with gamma-ferric-oxide shell 2009 Applied Physics A: Materials Science and Processing
    Vol. 94(3), pp. 619-625 
    article DOI  
    Abstract: Nanoparticles of solid solution Fe x Pt1−x , where 0.25≥x≥0 ( fcc lattice) with γ-Fe2O3 shell (lattice of the spinel type) were synthesised and characterised by high-resolution transmission electron microscopy, energy dispersive X-ray analysis, electron energy loss spectroscopy, Mössbauer spectroscopy and magnetometry. From the point of view of magnetic properties, such two-phase particles are interesting because their core is antiferromagnetic or paramagnetic (at very small values of x) whereas the shell is ferrimagnetic. The size of the particles was in the range of several nanometers. The Mössbauer measurements revealed a blocking temperature of about 100 K above which the particles are superparamagnetic. Towards lower temperatures, the magnetic characteristics of an ensemble of such particles show an increase of magnetic rigidity.
    BibTeX:
    @article{Basit2009,
      author = {Basit, L. and Nepijko, S. and Shukoor, I. and Ksenofontov, V. and Klimenkov, M. and Fecher, G. and Schönhense, G. and Tremel, W. and Felser, C.},
      title = {Structure and magnetic properties of iron-platinum particles with gamma-ferric-oxide shell},
      journal = {Applied Physics A: Materials Science and Processing},
      year = {2009},
      volume = {94},
      number = {3},
      pages = {619--625},
      doi = {http://dx.doi.org/10.1007/s00339-008-4874-7}
    }
    
    Berg, T., Maul, J., Schönhense, G., Marosits, E., Hoppe, P., Ott, U. & Palme, H. Direct Evidence for Condensation in the Early Solar System and Implications for Nebular Cooling Rates 2009 The Astrophysical Journal Letters
    Vol. 702(2), pp. L172-L176 
    article DOI  
    Abstract: We have identified in an acid resistant residue of the carbonaceous chondrite Murchison a large number (458) of highly refractory metal nuggets (RMNs) that once were most likely hosted by Ca,Al-rich inclusions (CAIs). While osmium isotopic ratios of two randomly selected particles rule out a presolar origin, the bulk chemistry of 88 particles with sizes in the submicron range determined by energy dispersive X-ray (EDX) spectroscopy shows striking agreement with predictions of single-phase equilibrium condensation calculations. Both chemical composition and morphology strongly favor a condensation origin. Particularly important is the presence of structurally incompatible elements in particles with a single-crystal structure, which also suggests the absence of secondary alteration. The metal particles represent the most pristine early solar system material found so far and allow estimation of the cooling rate of the gaseous environment from which the first solids formed by condensation. The resulting value of 0.5 K yr-1 is at least 4 orders of magnitude lower than the cooling rate of molten CAIs. It is thus possible, for the first time, to see through the complex structure of most CAIs and infer the thermal history of the gaseous reservoir from which their components formed by condensation.
    BibTeX:
    @article{Berg2009,
      author = {Berg, T. and Maul, J. and Schönhense, G. and Marosits, E. and Hoppe, P. and Ott, U. and Palme, H.},
      title = {Direct Evidence for Condensation in the Early Solar System and Implications for Nebular Cooling Rates},
      journal = {The Astrophysical Journal Letters},
      year = {2009},
      volume = {702},
      number = {2},
      pages = {L172--L176},
      doi = {http://dx.doi.org/10.1088/0004-637X/702/2/L172}
    }
    
    Gaier, O., Hamrle, J., Hillebrands, B., Kallmayer, M., Porsch, P., Schonhense, G., Elmers, H.J., Fassbender, J., Gloskovskii, A., Jenkins, C.A., Felser, C., Ikenaga, E., Sakuraba, Y., Tsunegi, S., Oogane, M. & Ando, Y. Improvement of structural, electronic, and magnetic properties of Co2MnSi thin films by He+ irradiation 2009 Appl. Phys. Lett.
    Vol. 94(15), pp. 152508-3 
    article DOI  
    BibTeX:
    @article{Gaier2009,
      author = {Gaier, O. and Hamrle, J. and Hillebrands, B. and Kallmayer, M. and Porsch, P. and Schonhense, G. and Elmers, H. J. and Fassbender, J. and Gloskovskii, A. and Jenkins, C. A. and Felser, C. and Ikenaga, E. and Sakuraba, Y. and Tsunegi, S. and Oogane, M. and Ando, Y.},
      title = {Improvement of structural, electronic, and magnetic properties of Co2MnSi thin films by He+ irradiation},
      journal = {Appl. Phys. Lett.},
      publisher = {AIP},
      year = {2009},
      volume = {94},
      number = {15},
      pages = {152508--3},
      doi = {http://dx.doi.org/10.1063/1.3119188}
    }
    
    Hild, K., Emmel, J., Schönhense, G. & Elmers, H.J. Threshold photoemission magnetic circular dichroism at the spin-reorientation transition of ultrathin epitaxial Pt/Co/Pt(111)/W(110) films 2009 Phys. Rev. B
    Vol. 80(22), pp. 224426- 
    article DOI  
    BibTeX:
    @article{Hild2009,
      author = {Hild, K. and Emmel, J. and Schönhense, G. and Elmers, H. J.},
      title = {Threshold photoemission magnetic circular dichroism at the spin-reorientation transition of ultrathin epitaxial Pt/Co/Pt(111)/W(110) films},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2009},
      volume = {80},
      number = {22},
      pages = {224426--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.80.224426}
    }
    
    Hild, K., Maul, J., Schönhense, G., Elmers, H.J., Amft, M. & Oppeneer, P.M. Magnetic Circular Dichroism in Two-Photon Photoemission 2009 Phys. Rev. Lett.
    Vol. 102(5), pp. 057207-4 
    article DOI  
    Abstract: We report the observation of magnetic circular dichroism (MCD) in two-photon photoemission (2PPE). The Heusler alloys Ni2MnGa and Co2FeSi were investigated by excitation with femtosecond laser light, showing MCD asymmetries of A=(3.5±0.5)×10-3 for Ni2MnGa and of A=(2.1±1.0)×10-3 for Co2FeSi, respectively. A theoretical explanation is provided based on local spin-density calculations for the magnetic dichroic response; the computed 2PPE MCD agrees well with the experiment. The observed 2PPE magnetic contrast represents an interesting alternative for future time-resolved photoemission studies on surface magnetism practicable in the laboratory.
    BibTeX:
    @article{Hild2009a,
      author = {Hild, K. and Maul, J. and Schönhense, G. and Elmers, H. J. and Amft, M. and Oppeneer, P. M.},
      title = {Magnetic Circular Dichroism in Two-Photon Photoemission},
      journal = {Phys. Rev. Lett.},
      publisher = {APS},
      year = {2009},
      volume = {102},
      number = {5},
      pages = {057207--4},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.102.057207}
    }
    
    Krasyuk, A., Wegelin, F., Nepijko, S., Elmers, H., Schönhense, G., Mönch, I., Vinzelberg, H. & Schneider, C. Dynamics of 180° Néel Walls in Two-Dimensional Permalloy Particles Observed Via Picosecond Time-Resolved Photoemission Electron Microscopy 2009 Ukrain. J. Phys.
    Vol. 54, pp. 170-175 
    article URL 
    BibTeX:
    @article{Krasyuk2009,
      author = {A. Krasyuk and F. Wegelin and S.A. Nepijko and H.J. Elmers and G. Schönhense and I. Mönch and H. Vinzelberg and C.M. Schneider},
      title = {Dynamics of 180° Néel Walls in Two-Dimensional Permalloy Particles Observed Via Picosecond Time-Resolved Photoemission Electron Microscopy},
      journal = {Ukrain. J. Phys.},
      year = {2009},
      volume = {54},
      pages = {170--175},
      url = {http://www.ujp.bitp.kiev.ua/files/papers/540127p.pdf}
    }
    
    Nepijko, S., Graff, A., Schönhense, G. & Schneider, C. Quantitative determination of magnetic fields from iron particles of oblong form encapsulated by carbon nanotubes using electron holography 2009 Applied Physics A: Materials Science & Processing
    Vol. 94(3), pp. 543-547 
    article DOI  
    Abstract: Using electron holography (interference electron microscopy) we have made measurements of the magnetic flux and magnetic field distribution around a carbon nanotube filled with iron. At the surface of the carbon nanotube, an iron particle with a radius of 30 nm and a length of 200 nm created a magnetic flux of 10E−15 Wb (Weber) and a magnetic field of 0.3–0.4 T (Tesla). The theory developed in this work is constrained to the case of cylindrical symmetry of the investigated ferromagnetic particles, but, in general, such studies can be made for ferromagnetic particles of any shape.
    BibTeX:
    @article{Nepijko2009,
      author = {Nepijko, S. and Graff, A. and Schönhense, G. and Schneider, C.},
      title = {Quantitative determination of magnetic fields from iron particles of oblong form encapsulated by carbon nanotubes using electron holography},
      journal = {Applied Physics A: Materials Science & Processing},
      year = {2009},
      volume = {94},
      number = {3},
      pages = {543--547},
      doi = {http://dx.doi.org/10.1007/s00339-008-4947-7}
    }
    
    Nepijko, S. & Schönhense, G. Measurement of potential distribution function on object surface by using an electron microscope in the mirror operation mode 2009 Journal of Microscopy(9999)  article DOI  
    Abstract: The quantitative theory of image contrast in an electron microscope in the mirror operation mode is given in this paper. This theory permits us to calculate the potential distribution on the object surface from the current density distribution on the microscope screen. The potential distribution results in image formation on the screen. Local electric fields existing on the object surface lead to a perturbation of electron trajectories above the object and to a redistribution of the current density on the screen, causing image contrast. Using the quantitative correlation between these fields and the function of current density distribution on the screen, it is possible to calculate the magnitude of these microfields as well. As illustration, a measured potential distribution on an object surface with spiral structures of adsorbates was analysed. These structures are formed during reaction of CO oxidation on Pt(110). The value of the measured contact potential difference comprised a few hundredths of volt.
    BibTeX:
    @article{Nepijko2009a,
      author = {Nepijko, S.A. and Schönhense, G.},
      title = {Measurement of potential distribution function on object surface by using an electron microscope in the mirror operation mode},
      journal = {Journal of Microscopy},
      year = {2009},
      number = {9999},
      doi = {http://dx.doi.org/10.1111/j.1365-2818.2009.03340.x}
    }
    
    Nepijko, S. & Schönhense, G. Quantitative Lorentz transmission electron microscopy of structured thin permalloy films 2009 Applied Physics A: Materials Science & Processing
    Vol. 96, pp. 671-677 
    article DOI  
    BibTeX:
    @article{Nepijko2009b,
      author = {Nepijko, S.A. and Schönhense, G.},
      title = {Quantitative Lorentz transmission electron microscopy of structured thin permalloy films},
      journal = {Applied Physics A: Materials Science & Processing},
      year = {2009},
      volume = {96},
      pages = {671-677},
      doi = {http://dx.doi.org/10.1007/s00339-009-5131-4}
    }
    
    Oelsner, A., Rohmer, M., Schneider, C., Bayer, D., Schönhense, G. & Aeschlimann, M. Time- and Energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations 2009 Journal of Electron Spectroscopy and Related Phenomena  article URL 
    Abstract: The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for real-time spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump-probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4d imaging (x,�y,�[Delta]t,�EKin) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction.By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108�ps absolute and 13.5�ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time resolved PEEM technique enables to display evolutions of spatially resolved (< 25�nm) and temporal sliced images life on any modern computer. The method allows dynamics investigations of variable electrical, magnetic, and optical near fields at surfaces and great prospects in dynamical adaptive photoelectron optics. For dynamical processes in the ps time scale such as magnetic domain wall movements, the time-resolution of the delay line detectors even allows to be used directly for real-time experiments as well.
    BibTeX:
    @article{Oelsner2009,
      author = {Oelsner, Andreas and Rohmer, Martin and Schneider, Christian and Bayer, Daniela and Schönhense, Gerd and Aeschlimann, Martin},
      title = {Time- and Energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      year = {2009},
      url = {http://www.sciencedirect.com/science/article/B6TGC-4XMKB4R-2/2/29d24f00b4817ff9a175462c6ce469a5}
    }
    
    Schneider, C., Krug, I., Müller, M., Matthes, F., Kaiser, A., Wiemann, C., Cramm, S., Elmers, H.-J., Wegelin, F., Krasyuk, A., Nepijko, S. & Schönhense, G. Investigating spintronics thin film systems with synchrotron radiation 2009 Radiation Physics and Chemistry
    Vol. 78(10, Supplement 1)Proceedings of the Nineth International School and Symposium on Synchrotron Radiation in Natural Science (ISSRNS-9) June 15-20, Ameliowka, Poland, pp. S5-S10 
    article DOI  
    Abstract: Spintronics is a research field involving a wide variety of different magnetic materials. Synchrotron radiation in the VUV and soft X-ray regime is ideally suited to investigate the relationships between magnetic properties and electronic structure of spintronics thin film stacks. Complex layered structures and nanomagnets are the main building blocks for current and future spintronics applications. In this contribution we describe the study of spintronics model systems with respect to the static and dynamic behavior with an emphasis on interfaces.
    BibTeX:
    @article{Schneider2009,
      author = {Schneider, C.M. and Krug, I. and Müller, M. and Matthes, F. and Kaiser, A. and Wiemann, C. and Cramm, S. and Elmers, H.-J. and Wegelin, F. and Krasyuk, A. and Nepijko, S.A. and Schönhense, G.},
      title = {Investigating spintronics thin film systems with synchrotron radiation},
      booktitle = {Proceedings of the Nineth International School and Symposium on Synchrotron Radiation in Natural Science (ISSRNS-9) June 15-20, Ameliowka, Poland},
      journal = {Radiation Physics and Chemistry},
      year = {2009},
      volume = {78},
      number = {10, Supplement 1},
      pages = {S5--S10},
      doi = {http://dx.doi.org/10.1016/j.radphyschem.2009.02.013}
    }
    
    Wegelin, F., Krasyuk, A., Valdaitsev, D.A., Nepijko, S.A., Elmers, H.J., Schönhense, G. & Schneider, C.M. Magnetization dynamics in polycrystalline Permalloy and epitaxial Co platelets observed by time-resolved photoemission electron microscopy 2009 physica status solidi (b)
    Vol. 246(7), pp. 1476-1482 
    article DOI  
    Abstract: We studied the dynamic magnetization response in rectangular polycrystalline Permalloy and also epitaxial Co structures (lateral sizes comprised tens of microns at a thickness of tens of nanometers) during the action of a magnetic field pulse, using time-resolved X-ray photoemission electron microscopy with a time resolution of 10 ps. In the case of Permalloy platelets the restoring torque that is necessary for the stroboscopic image acquisition is provided by the Landau flux closure structure representing a minimum of the free energy. We investigated the dynamic response of 90� N�el domain walls. The main results are: the maximum velocity of the domain wall is 1.5 � 104 m/s, the intrinsic frequency of the magnetization change in these structures is estimated to be several Gigahertz. For the case of epitaxial Co platelets grown on Mo(110) the magnetic uniaxial anisotropy with an easy axis along Mo[10] restores the homogeneous magnetization structure after each field pulse. We observed a rotation of the mean magnetization direction within the first 100 ps of the field pulse. (� 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    BibTeX:
    @article{Wegelin2009,
      author = {Wegelin, Frederik and Krasyuk, Alexander and Valdaitsev, Dmitrii A. and Nepijko, Sergej A. and Elmers, Hans Joachim and Schönhense, Gerd and Schneider, Claus M.},
      title = {Magnetization dynamics in polycrystalline Permalloy and epitaxial Co platelets observed by time-resolved photoemission electron microscopy},
      journal = {physica status solidi (b)},
      year = {2009},
      volume = {246},
      number = {7},
      pages = {1476--1482},
      doi = {http://dx.doi.org/10.1002/pssb.200844486}
    }
    
    Zimmer, C., Medyanyk, K., Schoenhense, G., Krischok, S., Lorenz, P., Schubert, J. & Doll, T. Low vacuum photo electron emitting thin films 2009 physica status solidi (a)
    Vol. 206(3), pp. 484-488 
    article DOI  
    Abstract: Impact ionisation is a standard procedure to ionise gaseous or vaporisable substances in organic mass spectrometry. In this work, a ldquosofterrdquo ionisation is introduced which seems to be an alternative ion source for reducing collision between substance molecules and the hot internal walls of the box. Through collision mainly found in impact ionisation sources, fragments are built especially from thermally sensitive substances falsifying the spectra. We present here photoelectron emitting materials for the soft ionisation using semiconducting compounds, galliumn nitride (GaN), and a representative of the borides, lanthanum hexaboride (LaB6). They are evaluated by photoelectron spectroscopic studies. (� 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    BibTeX:
    @article{Zimmer2009,
      author = {Zimmer, C. and Medyanyk, K. and Schoenhense, G. and Krischok, S. and Lorenz, P. and Schubert, J. and Doll, T.},
      title = {Low vacuum photo electron emitting thin films},
      journal = {physica status solidi (a)},
      year = {2009},
      volume = {206},
      number = {3},
      pages = {484--488},
      doi = {http://dx.doi.org/10.1002/pssa.200880477}
    }
    
    Berg, T., Marosits, E., Maul, J., Nagel, P., Ott, U., Schertz, F., Schuppler, S., Sudek, C. & Schönhense, G. Quantum confinement observed in the x-ray absorption spectrum of size distributed meteoritic nanodiamonds 2008 Journal of Applied Physics
    Vol. 104, pp. 064303 (5pp) 
    article DOI  
    Abstract: We present a near edge x-ray absorption fine structure study of artificial chemical vapor deposition diamonds with sizes in the micron range and of size distributed nanodiamonds extracted from the Murchison meteorite. The modified peak shape in the case of the nanodiamond sample is explained by the interplay between the size distribution of the nanodiamonds and quantum confinement effects within a quantitative analysis based on the effective mass approximation theory.
    BibTeX:
    @article{Berg2008,
      author = {T. Berg and E. Marosits and J. Maul and P. Nagel and U. Ott and F. Schertz and S. Schuppler and Ch. Sudek and G. Schönhense},
      title = {Quantum confinement observed in the x-ray absorption spectrum of size distributed meteoritic nanodiamonds},
      journal = {Journal of Applied Physics},
      year = {2008},
      volume = {104},
      pages = {064303 (5pp)},
      doi = {http://dx.doi.org/10.1063/1.2978217}
    }
    
    Gloskovskii, A., Valdaitsev, D., Cinchetti, M., Nepijko, S., Lange, J., Aeschlimann, M., Bauer, M., Klimenkov, M., Viduta, L., Tomchuk, P. & others Electron emission from films of Ag and Au nanoparticles excited by a femtosecond pump-probe laser 2008 Physical Review B
    Vol. 77(19), pp. 195427 
    article DOI  
    Abstract: Electron emission from Ag and Au nanoparticle films was studied under excitation with femtosecond-laser pulses with photon energies of 1.55 and 3.1 eV. Films were grown on a glass substrate with particle sizes from the nanometer range to a continuous layer. The transition from a continuous film to a nanoparticle film is accompanied by an increase in photoemission current by more than an order of magnitude. Pump-and-probe experiments with variable delay gave information on the lifetime of the intermediate states. At a fixed pulse power, the emission yield increases as the temporal width of the laser pulses is decreased. Experimental results are interpreted in terms of two different electron emission mechanisms, i.e., multiphoton photoemission and thermionic emission or thermally assisted multiphoton photoemission. The first mechanism prevails for continuous films and larger particles with sizes above several tens of nanometers; the second one prevails for smaller nanoparticles with sizes of a few nanometers.
    BibTeX:
    @article{Gloskovskii2008,
      author = {Gloskovskii, A. and Valdaitsev, DA and Cinchetti, M. and Nepijko, SA and Lange, J. and Aeschlimann, M. and Bauer, M. and Klimenkov, M. and Viduta, LV and Tomchuk, PM and others},
      title = {Electron emission from films of Ag and Au nanoparticles excited by a femtosecond pump-probe laser},
      journal = {Physical Review B},
      publisher = {APS},
      year = {2008},
      volume = {77},
      number = {19},
      pages = {195427},
      doi = {http://dx.doi.org/10.1103/PhysRevB.77.195427}
    }
    
    Hild, K., Maul, J., Meng, T., Kallmayer, M., Schönhense, G., Elmers, H., Ramos, R., Arora, S.K. & Shvets, I. Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film 2008 Journal of Physics: Condensed Matter
    Vol. 20, pp. 235218 (5pp) 
    article DOI  
    Abstract: Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe3O4) shows a magnetic circular dichroism of ~(4.5 ± 0.3) × 10-3 for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.
    BibTeX:
    @article{Hild2008,
      author = {K. Hild and J. Maul and T. Meng and M. Kallmayer and G. Schönhense and H.J. Elmers and R. Ramos and S. K. Arora and I.V. Shvets},
      title = {Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film},
      journal = {Journal of Physics: Condensed Matter},
      year = {2008},
      volume = {20},
      pages = {235218 (5pp)},
      doi = {http://dx.doi.org/10.1088/0953-8984/20/23/235218}
    }
    
    Hovorka, M., Frank, L., Valdaitsev, D., Nepijko, S., Elmers, H.-J. & Schönhense, G. High-pass Energy-Filtered PEEM Imaging of Dopants in Silicon 2008 J. Microsc.
    Vol. 230(1), pp. 42-47 
    article DOI  
    Abstract: Differently doped areas in silicon can show strong electron-optical contrast in dependence on the dopant concentration and surface conditions. Photoemission electron microscopy is a powerful surface-sensitive technique suitable for fast imaging of doping-induced contrast in semiconductors. We report on the observation of Si (100) samples with n- and p-type doped patterns (with the dopant concentration varied from 1016 to 1019 cm−3) on a p- and n-type substrate (doped to 1015 cm−3), respectively. A high-pass energy filter of the entire image enabled us to obtain spectroscopic information, i.e. quantified photo threshold and related photoyield differences depending on the doping level. Measurements have confirmed the possibility of resolving areas at a high contrast even with the lowest dopant concentration when employing the energy filter. The influence of electron absorption phenomena on contrast formation is discussed.
    BibTeX:
    @article{Hovorka2008,
      author = {M. Hovorka and L. Frank and D. Valdaitsev and S.A. Nepijko and H.-J. Elmers and G. Schönhense},
      title = {High-pass Energy-Filtered PEEM Imaging of Dopants in Silicon},
      journal = {J. Microsc.},
      year = {2008},
      volume = {230},
      number = {1},
      pages = {42-47},
      doi = {http://dx.doi.org/10.1111/j.1365-2818.2008.01953.x}
    }
    
    Lin, J., Maul, J., Weber, N., Holfeld, C., Escher, M., Merkel, M., Schoenhense, G. & Kleineberg, U. Inspection of EUVL mask blank defects and patterned masks using EUV photoemission electron microscopy 2008 Microelectronic Engineering
    Vol. 85(5-6), pp. 922-924 
    article DOI  
    Abstract: We report on recent developments of an “at-wavelength” full-field imaging technique for inspection of multilayer mask blank defects and patterned mask samples for extreme ultraviolet lithography (EUVL) by EUV photoemission electron microscopy (EUV-PEEM). A bump-type line defect with a width of approximately 35 nm that is buried beneath Mo/Si multilayer has been detected clearly, and first inspection results obtained from a patterned TaN absorber EUVL mask sample is reported. Different image contrast of a similar width of multilayer-covered substrate line defect and on top TaN absorber square has been observed in the EUV-PEEM images, and origin of the difference in their EUV-PEEM image contrast is discussed.
    BibTeX:
    @article{Lin2008,
      author = {Lin, J. and Maul, J. and Weber, N. and Holfeld, C. and Escher, M. and Merkel, M. and Schoenhense, G. and Kleineberg, U.},
      title = {Inspection of EUVL mask blank defects and patterned masks using EUV photoemission electron microscopy},
      journal = {Microelectronic Engineering},
      publisher = {Elsevier},
      year = {2008},
      volume = {85},
      number = {5-6},
      pages = {922-924},
      doi = {http://dx.doi.org/10.1016/j.mee.2008.01.087}
    }
    
    Lin, J., Weber, N., Escher, M., Maul, J., Han, H.-S., Merkel, M., Wurm, S., Schönhense, G. & Kleineberg, U. Three-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy 2008 Opt. Express
    Vol. 16(20), pp. 15343-15352 
    article URL 
    BibTeX:
    @article{Lin2008a,
      author = {Lin, Jingquan and Weber, Nils and Escher, Matthias and Maul, Jochen and Han, Hak-Seung and Merkel, Michael and Wurm, Stefan and Schönhense, Gerd and Kleineberg, Ulf},
      title = {Three-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy},
      journal = {Opt. Express},
      publisher = {OSA},
      year = {2008},
      volume = {16},
      number = {20},
      pages = {15343--15352},
      url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-16-20-15343}
    }
    
    Nepijko, S.A. & Schönhense, G. Size selective melting of small metal particles 2008 Metallofizika I Noveishie Tekhnologii
    Vol. 30(4), pp. 479-483 
    article  
    Abstract: Fine particles of lead in the size of 3-40 nm are grown epitaxially on thin monocrystalline MgO substrate transparent for an electron beam in a column of a transmission electron. microscope. Studying of their melting was carried out in situ. Particles of lead were heated by means of a heater containing a substrate with these particles and ail electron beam. Size dependences of melting temperature qualitatively differ for different ways of heating. In the first case, the melting temperature goes down with reduction of the size of a particle. In the second case, the size of a particle there is less, the greater energy of an electron beam is necessary for its melting.
    BibTeX:
    @article{Nepijko2008,
      author = {Nepijko, S. A. and Schönhense, G.},
      title = {Size selective melting of small metal particles},
      journal = {Metallofizika I Noveishie Tekhnologii},
      publisher = {Natl Acad Sciences Ukraine, Inst Metal Physics},
      year = {2008},
      volume = {30},
      number = {4},
      pages = {479--483}
    }
    
    Panzer, D., Beck, C., Maul, J., Möller, M., Decker, H. & Schönhense, G. Transmission photoemission electron microscopy for lateral mapping of the X-ray absorption structure of a metalloprotein in a liquid cell 2008 Europ. Biophys. Journal  article DOI  
    Abstract: We use photoemission electron microscopy in an X-ray transmission mode for full-field imaging of the X-ray absorption structure of copper in the respiratory metalloprotein hemocyanin KLH1. It contains 160 oxygen binding sites. Each site reversibly binds one molecule oxygen between two copper atoms. In our setup, hemocyanin is dissolved in aqueous solution and enclosed in an ultra-high vacuum compatible liquid sample cell with silicon nitride membranes. The local X-ray absorption structure of the liquid sample is converted into photoelectrons at the microscope side of the cell acting as a photocathode. In this way, different copper valencies are laterally distinguished under in vivo-like conditions, attributed to Cu(I) in the deoxy-state and Cu(II) in the oxy-state.
    BibTeX:
    @article{Panzer2008,
      author = {D. Panzer and C. Beck and J. Maul and M. Möller and H. Decker and G. Schönhense},
      title = {Transmission photoemission electron microscopy for lateral mapping of the X-ray absorption structure of a metalloprotein in a liquid cell},
      journal = {Europ. Biophys. Journal},
      year = {2008},
      doi = {http://dx.doi.org/10.1007/s00249-008-0355-3}
    }
    
    Weber, N.B., Escher, M., Merkel, M., Oelsner, A. & Schönhense, G. Energy- and time-resolved microscopy using PEEM: recent developments and state-of-the-art 2008 Journal of Physics: Conference Series(7), pp. 072031  article DOI  
    Abstract: Two novel methods of spectroscopic surface imaging are discussed, both based on photoemission electron microscopy PEEM. They are characterised by a simple electron-optical set up retaining a linear column. An imaging high-pass energy filter has been developed on the basis of lithographically-fabricated microgrids. Owing to a mesh size of only 7mm, no image distortions occur. The present energy resolution is 70 meV. The second approach employs time-of-flight energy dispersion and time-resolved detection using a Delayline Detector. In this case, the drift energy and the time resolution of the detector determine the energy resolution. The present time resolution is 180 ps, giving rise to an energy resolution in the 100 meV range.
    BibTeX:
    @article{Weber2008,
      author = {Weber, N B and Escher, M and Merkel, M and Oelsner, A and Schönhense, G},
      title = {Energy- and time-resolved microscopy using PEEM: recent developments and state-of-the-art},
      journal = {Journal of Physics: Conference Series},
      year = {2008},
      number = {7},
      pages = {072031},
      doi = {http://dx.doi.org/10.1088/1742-6596/100/7/072031}
    }
    
    Fecher, G.H., Balke, B., Ouardi, S., Felser, C., Schönhense, G., Ikenaga, E., Kim, J.J., Ueda, S. & Kobayashi, K. High energy, high resolution photoelectron spectroscopy of Co2Mn1-xFexSi 2007 Journal Of Physics D-Applied Physics
    Vol. 40(6), pp. 1576-1581 
    article DOI  
    Abstract: This work reports on high resolution photoelectron spectroscopy for the valence band of Co2Mn1-xFexSi ( x = 0, 0.5, 1) excited by photons of about 8 keV energy. The measurements show good agreement with calculations of the electronic structure using the LDA + U scheme. It is shown that the high energy spectra reveal the bulk electronic structure better compared with low energy x-ray photoelectron spectroscopy spectra. The high resolution measurements of the valence band close to the Fermi energy indicate the existence of the gap in the minority states for all the three alloys.
    BibTeX:
    @article{Fecher2007,
      author = {Fecher, G. H. and Balke, B. and Ouardi, S. and Felser, C. and Schönhense, G. and Ikenaga, E. and Kim, J. J. and Ueda, S. and Kobayashi, K.},
      title = {High energy, high resolution photoelectron spectroscopy of Co2Mn1-xFexSi},
      journal = {Journal Of Physics D-Applied Physics},
      publisher = {Iop Publishing Ltd},
      year = {2007},
      volume = {40},
      number = {6},
      pages = {1576--1581},
      doi = {http://dx.doi.org/10.1088/0022-3727/40/6/S11}
    }
    
    Frank, L., Mika, F., Hovorka, M., Valdaitsev, D., Schönhense, G. & Mullerova, I. Dopant contrast in semiconductors as interpretation challenge at imaging by electrons 2007 Materials Transactions
    Vol. 48(5), pp. 936-939 
    article  
    Abstract: Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.
    BibTeX:
    @article{Frank2007,
      author = {Frank, L. and Mika, F. and Hovorka, M. and Valdaitsev, D. and Schönhense, G. and Mullerova, I.},
      title = {Dopant contrast in semiconductors as interpretation challenge at imaging by electrons},
      journal = {Materials Transactions},
      publisher = {Japan Inst Metals},
      year = {2007},
      volume = {48},
      number = {5},
      pages = {936--939}
    }
    
    Gloskovskii, A., Nepijko, S.A., Schönhense, G., Therese, H.A., Reiber, A., Kandpal, H.C., Fecher, G.H., Felser, C., Tremel, W. & Klimenkov, M. Spectroscopic and microscopic study of vanadium oxide nanotubes 2007 Journal Of Applied Physics
    Vol. 101(8), pp. 084301 
    article DOI  
    Abstract: V2O5 nanotubes synthesized via the sol-gel route has been studied by electron energy loss spectroscopy (EELS), x-ray absorption spectroscopy (XAS), and energy dispersive x-ray analysis, in order to understand the local structure of vanadium in the nanotubes. Contrary to our expectation, all the features of the XAS and EELS spectra of the V2O5 nanotubes are in line with that of bulk layered vanadium oxide revealing that vanadium is present in the 5(+) oxidation state in the nanotubes. However, V2O5 nanotubes exhibit additional surface states in their electronic structure in comparison with bulk V2O5. A comparison of measured and calculated spectra allows us to distinguish single-wall from multiwall V2O5 nanotubes. (c) 2007 American Institute of Physics.
    BibTeX:
    @article{Gloskovskii2007,
      author = {Gloskovskii, A. and Nepijko, S. A. and Schönhense, G. and Therese, H. A. and Reiber, A. and Kandpal, H. C. and Fecher, G. H. and Felser, C. and Tremel, W. and Klimenkov, M.},
      title = {Spectroscopic and microscopic study of vanadium oxide nanotubes},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {2007},
      volume = {101},
      number = {8},
      pages = {084301},
      doi = {http://dx.doi.org/10.1063/1.2716157}
    }
    
    Gloskovskii, A., Valdaitsev, D., Nepijko, S., Schönhense, G. & Rethfeld, B. Coexisting electron emission mechanisms in small metal particles observed in fs-laser excited PEEM 2007 Surface Science
    Vol. 601(20), pp. 4706-4713 
    article DOI  
    Abstract: Silver cluster films deposited on Si(1 1 1) were investigated by spectroscopic photoelectron microscopy using fs-laser excitation tuneable between h[nu] = 1.45-1.65 eV and 2.9-3.3 eV. With increasing coverage the films grown as stepped wedges first exhibit clusters of few nanometers diameter with narrow size distributions that later agglomerate forming larger islands up to about 100 nm diameter. The cluster films have been characterized by SEM, AFM and HR-TEM. In the 3.1 eV range the small clusters emit more effectively and the dependence of electron yield on laser power follows a quadratic power law. Microspectroscopy reveals that the Fermi level onset is sharp(<150 meV width) and shifts by 2h[nu] when the quantum energy is increased, thus confirming the predominance of two-photon-photoemission (2PPE). Under 1.6 eV excitation the situation is different: The power dependence is non-integer and the slope varies between 2.9 and 3.7 for different points on the sample. The Fermi edge appears smeared out and shifted by several hundred meV to lower final state energies. We attribute this deviation from pure 3PPE to thermally assisted nPPE of electrons from a transient "hot electron" gas in the nanoparticles.
    BibTeX:
    @article{Gloskovskii2007a,
      author = {Gloskovskii, A. and Valdaitsev, D. and Nepijko, S.A. and Schönhense, G. and Rethfeld, B.},
      title = {Coexisting electron emission mechanisms in small metal particles observed in fs-laser excited PEEM},
      journal = {Surface Science},
      year = {2007},
      volume = {601},
      number = {20},
      pages = {4706--4713},
      doi = {http://dx.doi.org/10.1016/j.susc.2007.05.046}
    }
    
    Gloskovskii, A., Barth, J., Balke, B., Fecher, G.H., Felser, C., Kronast, F., Ovsyannikov, R., Durr, H., Eberhard, W. & Schönhense, G. A spatially resolved investigation of the local, micro-magnetic domain structure of single and polycrystalline Co2FeSi 2007 Journal Of Physics D-Applied Physics
    Vol. 40(6), pp. 1570-1575 
    article DOI  
    Abstract: The Heusler compound Co2FeSi is a promising material for magneto-electronic devices. With a Curie temperature of 1100K and a saturation magnetization of 6 Bohr magnetons and a high spin polarization at the Fermi edge it fulfils the essential requirements for magnetic sensors or spin valve structures. An essential feature for such devices is the micro-magnetic domain structure. X-ray magnetic circular dichroism - photo emission electron microscopy has been used for a direct observation of the domain structure of single- and polycrystalline samples. The polycrystalline material exhibits a micro-magnetic ripple structure, as it is well known for pure Co and other polycrystalline Heusler compounds. The ( 1 1 0)- oriented surface of the single crystal exhibits a multi-domain pattern characteristic for systems with an easy axis that might point out of the surface. Asymmetric 180. Bloch walls with changing sense of rotation are observed between oppositely magnetized domains. Spin polarized photo emission from a single domain of the single crystal shows a spin polarization of 16% at the Fermi energy and up to 35% in the d-bands, at room temperature.
    BibTeX:
    @article{Gloskovskii2007b,
      author = {Gloskovskii, A. and Barth, J. and Balke, B. and Fecher, G. H. and Felser, C. and Kronast, F. and Ovsyannikov, R. and Durr, H. and Eberhard, W. and Schönhense, G.},
      title = {A spatially resolved investigation of the local, micro-magnetic domain structure of single and polycrystalline Co2FeSi},
      journal = {Journal Of Physics D-Applied Physics},
      publisher = {Iop Publishing Ltd},
      year = {2007},
      volume = {40},
      number = {6},
      pages = {1570--1575},
      doi = {http://dx.doi.org/10.1088/0022-3727/40/6/S10}
    }
    
    Krasyuk, A., Nepijko, S.A., Oelsner, A., Schneider, C.M., Elmers, H.J. & Schönhense, G. Magnetic stray fields of patterned permalloy structures investigated by photoemission electron microscopy 2007 Applied Physics A-Materials Science & Processing
    Vol. 88(4), pp. 793-796 
    article DOI  
    Abstract: Using a photoemission electron microscope we determined magnetic stray fields at the edges of permalloy (Ni80Fe20) particles. X-ray magnetic dichroism was used for visualization of magnetic domains. The values of the stray fields were deduced from the deflection of electrons in the image due to the Lorentz force. The stray fields are responsible for the magnetic interaction of adjacent particles with distances much larger than the thickness. The measured magnetic stray field is about 0.023 T for rectangular particles with a thickness of 30 nm and lateral sizes of tens of microns.
    BibTeX:
    @article{Krasyuk2007,
      author = {Krasyuk, A. and Nepijko, S. A. and Oelsner, A. and Schneider, C. M. and Elmers, H. J. and Schönhense, G.},
      title = {Magnetic stray fields of patterned permalloy structures investigated by photoemission electron microscopy},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2007},
      volume = {88},
      number = {4},
      pages = {793--796},
      doi = {http://dx.doi.org/10.1007/s00339-007-4085-7}
    }
    
    Lin, J.Q., Neuhäusler, U., Slieh, J., Brechling, A., Heinzmann, U., Weber, N., Escher, M., Merkel, M., Oelsner, A., Valdaitsev, D., Schönhense, G., Quesnel, E. & Kleineberg, U. Actinic inspection of EUVL mask blank defects by photoemission electron microscopy: Effect of inspection wavelength variation 2007 Microelectronic Engineering
    Vol. 84(5-8), pp. 1011-1014 
    article DOI  
    Abstract: Extreme ultraviolet (EUV) photoemission electron microscopy (PEEM), which employs standing wave field illumination of a sample, is a potential tool for at-wavelength inspection of phase defects on extreme ultraviolet lithography (EUVL) mask blank. In this paper, we will demonstrate that the contrast of an underneath multilayer programmed defect in EUV-PEEM image is strongly dependent on the inspection wavelength. The observed contrast variation at different inspection wavelengths is in good agreement with the simulation result of a standing wave field on surface of multilayer stack in the mask blank sample. We also observed some native defects on the programmed defect sample, and found that some of them reverse their contrast with varying inspection wavelengths while others do not. (c) 2007 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Lin2007,
      author = {Lin, J. Q. and Neuhäusler, U. and Slieh, J. and Brechling, A. and Heinzmann, U. and Weber, N. and Escher, M. and Merkel, M. and Oelsner, A. and Valdaitsev, D. and Schönhense, G. and Quesnel, E. and Kleineberg, U.},
      title = {Actinic inspection of EUVL mask blank defects by photoemission electron microscopy: Effect of inspection wavelength variation},
      journal = {Microelectronic Engineering},
      publisher = {Elsevier Science Bv},
      year = {2007},
      volume = {84},
      number = {5-8},
      pages = {1011--1014},
      doi = {http://dx.doi.org/10.1016/j.mee.2007.01.106}
    }
    
    Lin, J.Q., Weber, N., Maul, J., Hendel, S., Rott, K., Merkel, M., Schönhense, G. & Kleineberg, U. At-wavelength inspection of sub-40 nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy 2007 Optics Letters
    Vol. 32(13), pp. 1875-1877 
    article URL 
    Abstract: A new at-wavelength inspection technology to probe nanoscale defects buried underneath Mo/Si multilayers on an extreme ultraviolet (EUV) lithography mask blank has been implemented using EUV photoemission electron microscopy (EUV-PEEM). EUV-PEEM images of programmed defect structures of various lateral and vertical sizes recorded at an similar to 13.5 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps, enhancing the edge visibility of the phase defects, which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination. (c) 2007 Optical Society of America.
    BibTeX:
    @article{Lin2007a,
      author = {Lin, J. Q. and Weber, N. and Maul, J. and Hendel, S. and Rott, K. and Merkel, M. and Schönhense, G. and Kleineberg, U.},
      title = {At-wavelength inspection of sub-40 nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy},
      journal = {Optics Letters},
      publisher = {Optical Soc Amer},
      year = {2007},
      volume = {32},
      number = {13},
      pages = {1875--1877},
      url = {http://ol.osa.org//abstract.cfm?id=138642}
    }
    
    Martyanov, O.N., Yudanov, V.F., Lee, R.N., Nepijko, S.A., Elmers, H.J., Hertel, R., Schneider, C.M. & Schönhense, G. Ferromagnetic resonance study of thin film antidot arrays: Experiment and micromagnetic simulations 2007 Physical Review B
    Vol. 75(17), pp. 174429 
    article DOI  
    Abstract: The dynamic magnetic properties of two-dimensional periodic Co antidot arrays were studied by X-band ferromagnetic resonance. The experimental results on geometrically scaled antidot arrays reveal a strong attenuation of the uniform ferromagnetic resonance mode in comparison to a continuous film, but an excitation of nonuniform in-plane spin-wave modes. Micromagnetic finite-element simulations show that the static magnetic structure in an antidot array depends on the direction of the external field with respect to the symmetry axes of the antidot lattice, even if the external field is strong enough to enforce a technically saturated magnetization state. The analysis gives evidence that characteristic inhomogeneities in the magnetization distribution around the antidots give rise to the changes of the resonance modes with the in-plane direction of the magnetization.
    BibTeX:
    @article{Martyanov2007,
      author = {Martyanov, O. N. and Yudanov, V. F. and Lee, R. N. and Nepijko, S. A. and Elmers, H. J. and Hertel, R. and Schneider, C. M. and Schönhense, G.},
      title = {Ferromagnetic resonance study of thin film antidot arrays: Experiment and micromagnetic simulations},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2007},
      volume = {75},
      number = {17},
      pages = {174429},
      doi = {http://dx.doi.org/10.1103/PhysRevB.75.174429}
    }
    
    Maul, J., Lin, J., Oelsner, A., Valdaitsev, D., Weber, N., Escher, M., Merkel, M., Seitz, H., Heinzmann, U., Kleineberg, U. & Schönhense, G. Phase defect inspection of multilayer masks for 13.5 nm optical lithography using PEEM in a standing wave mode 2007 Surface Science
    Vol. 601(20), pp. 4758-4763 
    article DOI  
    Abstract: We report on recent developments of an "at wavelength" full-field imaging technique for defect inspection of multilayer mask blanks for extreme ultraviolet lithography (EUVL). Our approach uses photoemission electron microscopy (PEEM) in a near normal incidence mode at 13.5 nm wavelength to image the photoemission induced by the EUV wave field on the multilayer blank surface. We analyze buried defects on Mo/Si multilayer samples down to a lateral size of 50 nm and report on first results obtained from a six inches mask blank prototype as prerequisite for industrial usage.
    BibTeX:
    @article{Maul2007,
      author = {Maul, J. and Lin, J. and Oelsner, A. and Valdaitsev, D. and Weber, N. and Escher, M. and Merkel, M. and Seitz, H. and Heinzmann, U. and Kleineberg, U. and Schönhense, G.},
      title = {Phase defect inspection of multilayer masks for 13.5 nm optical lithography using PEEM in a standing wave mode},
      journal = {Surface Science},
      year = {2007},
      volume = {601},
      number = {20},
      pages = {4758--4763},
      doi = {http://dx.doi.org/10.1016/j.susc.2007.05.041}
    }
    
    Nepijko, S.A., Mundschau, M. & Schönhense, G. Photoemission electron microscopy of neodymium-iron-boron (Nd2Fe14B) 2007 Applied Physics A-Materials Science & Processing
    Vol. 86(4), pp. 515-519 
    article DOI  
    Abstract: The magnetic domain structure of a neodymium-iron-boron single crystal (Nd2Fe14B) was investigated in a photoemission electron microscope equipped with an aperture for partial restriction of the electron beam. As a result of the influence of magnetic microfields, electron trajectories are deflected in such a way that some of them are stopped by the aperture in the electron optical path. As a result, the contrast caused by the stray fields of the magnetic domains is significantly enhanced. The distribution of the local magnetic fields at the surface is reconstructed from the image by means of the proposed theory on the contrast mechanism. The size of the stray field close to the sample surface under study was 0.5-0.7 T.
    BibTeX:
    @article{Nepijko2007,
      author = {Nepijko, S. A. and Mundschau, M. and Schönhense, G.},
      title = {Photoemission electron microscopy of neodymium-iron-boron (Nd2Fe14B)},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2007},
      volume = {86},
      number = {4},
      pages = {515--519},
      doi = {http://dx.doi.org/10.1007/s00339-006-3803-x}
    }
    
    Nepijko, S., Marx, G. & Schönhense, G. Quantitative determination of magnetic fields on object surfaces via photoemission electron microscopy without restriction of the electron beam 2007 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
    Vol. 264(1), pp. 194-200 
    article DOI  
    Abstract: The stray magnetic field of domains on the surface of Nd17Fe17Cu5B5 and SmFe10Ti89 samples was visualized by emission electron microscopy in the regime without restriction of the electron rays by a contrast aperture. The distribution of the tangential and normal components of the magnetic field on the surface under study was derived from the image contrast. The experimental uncertainty of the performed quantitative measurements of the magnetic field is estimated as 15-20%, however, the applied technique has a principal error that is several times smaller.
    BibTeX:
    @article{Nepijko2007a,
      author = {Nepijko, S.A. and Marx, G.K.L. and Schönhense, G.},
      title = {Quantitative determination of magnetic fields on object surfaces via photoemission electron microscopy without restriction of the electron beam},
      journal = {Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms},
      year = {2007},
      volume = {264},
      number = {1},
      pages = {194--200},
      doi = {http://dx.doi.org/10.1016/j.nimb.2007.08.076}
    }
    
    Schönhense, G. & Elmers, H.J. Stroboscopic XMCD-PEEM imaging 2007 Encyclopedia of Materials: Science and Technology  incollection  
    BibTeX:
    @incollection{Schoenhense2007,
      author = {Schönhense, G. and Elmers, H. J.},
      title = {Stroboscopic XMCD-PEEM imaging},
      booktitle = {Encyclopedia of Materials: Science and Technology},
      publisher = {Elsevier},
      year = {2007}
    }
    
    Wegelin, F., Krasyuk, A., Elmers, H.-J., Nepijko, S.A., Schneider, C.M. & Schönhense, G. Stroboscopic XMCD-PEEM imaging of standing and propagating spinwave modes in permalloy thin-film structures 2007 Surface Science
    Vol. 601(20), pp. 4694-4699 
    article DOI  
    Abstract: Using synchrotron-based stroboscopic photoemission electron microscopy with X-ray circular dichroism as contrast method, we have investigated the high-frequency response of permalloy thin-film structures. Standing precessional modes have been studied in rectangular elements (16 x 32 [mu]m2, 10 nm thick) with a high time resolution of about 15 ps in the low-[alpha] mode of BESSY. With increasing amplitude of the applied magnetic AC field the particle is driven from an initial symmetric Landau flux-closure state into an asymmetric state and finally into a single-domain state magnetized perpendicular to the applied field HAC. The electromagnetic microwave field thus can induces a net magnetization in a small particle. This behaviour is a result of the constant throughput of energy (open system) that allows for an increase of local order, contrary to the usual increase on entropy in closed systems. A propagating spinwave in an ultrathin elliptical particle (semi axes 6 x 12 [mu]m2, 3 nm thick) was observed in a snapshot series with 25 ps time increment. The phase front of the spinwave with large precessional angle (bright contrast) propagates with a velocity of 8100 m/s, i.e. much faster than typical domain wall velocities in permalloy.
    BibTeX:
    @article{Wegelin2007,
      author = {Wegelin, Frederik and Krasyuk, Alexander and Elmers, Hans-Joachim and Nepijko, Sergej A. and Schneider, Claus M. and Schönhense, Gerd},
      title = {Stroboscopic XMCD-PEEM imaging of standing and propagating spinwave modes in permalloy thin-film structures},
      journal = {Surface Science},
      year = {2007},
      volume = {601},
      number = {20},
      pages = {4694--4699},
      doi = {http://dx.doi.org/10.1016/j.susc.2007.05.060}
    }
    
    Wegelin, F., Valdaitsev, D., Krasyuk, A., Nepijko, S.A., Schönhense, G., Elmers, H.J., Krug, I. & Schneider, C.M. Magnetization dynamics in microscopic spin-valve elements: Shortcomings of the macrospin picture 2007 Phys. Rev. B
    Vol. 76(13), pp. 134410-+ 
    article DOI  
    Abstract: We have studied ultrafast magnetodynamics in micropatterned spin-valve structures using time-resolved x-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism. Exciting the system with ultrafast field pulses of 250ps width, we find the dynamic response of the free layer to fall into two distinctly different contributions. On the one hand, it exhibits localized spin wave modes that strongly depend on the shape of the micropattern. A field pulse applied perpendicular to the exchange bias field along the diagonal of a square pattern leads to the excitation of a standing spin wave mode with two nodes along the field direction. This mode is strongly suppressed for a pattern of elliptical shape. On the other hand, the integrated response of the free layer roughly follows a single-spin model with a damping constant of α=0.025 independent of the shape and resembles the response of a critically damped forced oscillator.
    BibTeX:
    @article{Wegelin2007a,
      author = {Wegelin, F. and Valdaitsev, D. and Krasyuk, A. and Nepijko, S.~A. and Schönhense, G. and Elmers, H.~J. and Krug, I. and Schneider, C.~M.},
      title = {Magnetization dynamics in microscopic spin-valve elements: Shortcomings of the macrospin picture},
      journal = {Phys. Rev. B},
      year = {2007},
      volume = {76},
      number = {13},
      pages = {134410-+},
      doi = {http://dx.doi.org/10.1103/PhysRevB.76.134410}
    }
    
    Berg, T., Maul, J., Erdmann, N., Bernhard, P., Schuppler, S., Nagel, P., Sudek, C., Ott, U. & Schönhense, G. Coupling of imaging NEXAFS with secondary ion mass spectrometry for the chemical and isotopic analysis of presolar cosmic grains 2006 Analytical And Bioanalytical Chemistry
    Vol. 386(1), pp. 119-124 
    article DOI  
    Abstract: We present first results of the combination of imaging photoemission electron spectroscopy with imaging mass spectrometry. Imaging NEXAFS was combined with TOF-SIMS in order to perform a spatially resolved chemical and isotopic analysis of microscopic grain samples. Imaging NEXAFS was used for the nondestructive lateral characterization of mineral phases prior to isotopically resolved mass analysis by imaging TOF-SIMS. This novel approach was demonstrated by performing a chemical and isotopic analysis of the rare presolar grain fraction present in the Murchison meteorite.
    BibTeX:
    @article{Berg2006,
      author = {Berg, T. and Maul, J. and Erdmann, N. and Bernhard, P. and Schuppler, S. and Nagel, P. and Sudek, C. and Ott, U. and Schönhense, G.},
      title = {Coupling of imaging NEXAFS with secondary ion mass spectrometry for the chemical and isotopic analysis of presolar cosmic grains},
      journal = {Analytical And Bioanalytical Chemistry},
      publisher = {Springer Heidelberg},
      year = {2006},
      volume = {386},
      number = {1},
      pages = {119--124},
      doi = {http://dx.doi.org/10.1007/s00216-006-0590-3}
    }
    
    Bernhard, P., Maul, J., Ott, U., Sudek, C., Escher, M., Weber, N., Merkel, M., Kromker, B., Funnemann, D. & Schönhense, G. Trace element analysis in pre-solar stardust grains via full-field imaging XPS (nano-ESCA) 2006 Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms
    Vol. 246(1), pp. 275-280 
    article DOI  
    Abstract: An acid-resistant, SiC-rich, residue from the Murchison meteorite was investigated by means of a novel imaging XPS instrument. The micrometer-sized grains were deposited on a Si wafer from an aqueous suspension. Energy filtered ESCA images have been taken in the kinetic energy range from the threshold tip to about 400 eV for various photon energies. A lateral resolution of the order of 120 nm along with a high energy resolution in the range of 100 meV provides the basis for chemical trace element analysis with maximum sensitivity. Apart from major (Si, C) and minor (N, Mg, Al, Fe) elements, the energy filtered images and local microspectra revealed the presence of a variety of heavy trace elements: Sr, Y, Zr, Nb, Mo, Ba and, interestingly the rare earth elements Dy, Er and possibly Tm. Nano-ESCA thus provides a powerful non-destructive screening method for a later analysis of isotopic abundance anomalies using, e.g. Nano-SIMS. (c) 2006 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Bernhard2006,
      author = {Bernhard, P. and Maul, J. and Ott, U. and Sudek, C. and Escher, M. and Weber, N. and Merkel, M. and Kromker, B. and Funnemann, D. and Schönhense, G.},
      title = {Trace element analysis in pre-solar stardust grains via full-field imaging XPS (nano-ESCA)},
      journal = {Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms},
      publisher = {Elsevier Science Bv},
      year = {2006},
      volume = {246},
      number = {1},
      pages = {275--280},
      doi = {http://dx.doi.org/10.1016/j.nimb.2005.12.059}
    }
    
    Bernhard, P., Maul, J., Berg, T., Wegelin, F., Ott, U., Sudek, C., Spiecker, H., Merchel, S. & Schönhense, G. Nondestructive full-field imaging XANES-PEEM analysis of cosmic grains 2006 Physical Review B
    Vol. 74(7), pp. 079904 
    article DOI  
    Abstract: For chemical analysis of submicron particles, mass spectrometric methods have the disadvantage of being destructive. Thus, a nondestructive elemental and chemical mapping with a high spatial resolution prior to mass analysis is extremely valuable to precharacterize the sample. Here, first results are presented of combined XANES (x-ray absorption near-edge structure) and PEEM (photoemission electron microscopy) measurements on a cosmic grain fraction from the Murchison meteorite. This nondestructive full-field imaging method is well suited for a quantitative analysis and for a preselection prior to detailed mass spectrometric investigations with isotopic resolution/selectivity. A spectral unmixing algorithm helped to distinguish between elements in different binding surroundings and therefore to obtain lateral information about the elemental composition and the chemical structure. Individual Al2O3 and SiO2 grains as well as Cr-rich grains could be identified among the majority of SiC grains. This method is suited not only for meteoritic material but can in general be applied to composite grain materials of submicron sizes.
    BibTeX:
    @article{Bernhard2006a,
      author = {Bernhard, P. and Maul, J. and Berg, T. and Wegelin, F. and Ott, U. and Sudek, C. and Spiecker, H. and Merchel, S. and Schönhense, G.},
      title = {Nondestructive full-field imaging XANES-PEEM analysis of cosmic grains},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2006},
      volume = {74},
      number = {7},
      pages = {079904},
      doi = {http://dx.doi.org/10.1103/PhysRevB.74.075401}
    }
    
    Fecher, G.H., Kandpal, H.C., Wurmehl, S., Felser, C. & Schönhense, G. Slater-Pauling rule and Curie temperature of Co-2-based Heusler compounds 2006 Journal Of Applied Physics
    Vol. 99(8), pp. 08J106 
    article DOI  
    Abstract: A concept is presented serving to guide in the search for materials with high spin polarization. It is shown that the magnetic moment of half-metallic ferromagnets can be calculated from the generalized Slater-Pauling rule. Furthermore, it was found empirically that the Curie temperature of Co-2-based Heusler compounds can be estimated from a seemingly linear dependence on the magnetic moment. As a successful application of these simple rules, it was found that Co2FeSi is, actually, the half-metallic ferromagnet exhibiting the highest magnetic moment and the highest Curie temperature measured for a Heusler compound.
    BibTeX:
    @article{Fecher2006,
      author = {Fecher, G. H. and Kandpal, H. C. and Wurmehl, S. and Felser, C. and Schönhense, G.},
      title = {Slater-Pauling rule and Curie temperature of Co-2-based Heusler compounds},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {2006},
      volume = {99},
      number = {8},
      pages = {08J106},
      doi = {http://dx.doi.org/10.1063/1.2167629}
    }
    
    Frank, L., Mullerova, I., Valdaitsev, D.A., Gloskovskii, A., Nepijko, S.A., Elmers, H.J. & Schönhense, G. The origin of contrast in the imaging of doped areas in silicon by slow electrons 2006 Journal Of Applied Physics
    Vol. 100(9), pp. 093712 
    article DOI  
    Abstract: The importance of high resolution imaging of dopant contrast in semiconductor structures parallels the continuous increase in the degree of their integration and complexity and in the size of substrates. Some scanning electron microscopy modes show moderate contrast between differently doped areas, but its detailed interpretation remains questionable, in particular, as regards the measurement of the dopant concentration. Photoemission spectromicroscopy on silicon substrates with patterns of opposite-type dopants suggests that the p/n contrast is primarily related to local differences in the absorption of hot electrons along their trajectory toward the surface. This explanation is also expected to be valid in the interpretation of image contrasts formed by secondary electrons or very slow backscattered electrons. Wide-field photoemission electron microscopy has proven itself a fast imaging method providing large p-n contrast and the prospect of high-level resolution. (c) 2006 American Institute of Physics.
    BibTeX:
    @article{Frank2006,
      author = {Frank, L. and Mullerova, I. and Valdaitsev, D. A. and Gloskovskii, A. and Nepijko, S. A. and Elmers, H. J. and Schönhense, G.},
      title = {The origin of contrast in the imaging of doped areas in silicon by slow electrons},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {2006},
      volume = {100},
      number = {9},
      pages = {093712},
      doi = {http://dx.doi.org/10.1063/1.2364044}
    }
    
    Gloskovskii, A., Nepijko, S.A., Cinchetti, M., Schönhense, G., Fecher, G.H., Kandpal, H.C., Felser, C., Therese, H.A., Zink, N., Tremel, W. & Oelsner, A. Time-of-flight photoelectron spectromicroscopy of single MoS2 nanotubes 2006 Journal Of Applied Physics
    Vol. 100(8), pp. 084330 
    article DOI  
    Abstract: There is a recent interest in nanoscale materials, in particular, nanotubes based not only on carbon. In this study, photoemission spectra of single MoS2 nanotubes deposited on a Si surface were recorded in order to explain their electronic structure. The photoelectrons were excited by a femtosecond laser oscillator resulting in two-photon photoemission. A spectromicroscopic technique based on imaging time-of-flight detection was used to record the spatially resolved photoelectron spectra. Self-consistent electronic structure calculations for MoS2 slabs using the full potential linear augmented plane wave method are used to explain the peculiarities of the observed spectra. It turns out that the MoS2 nanotubes are semiconducting with a band gap of about 1 eV. The two-photon transitions proceed through intermediate states in a region with high density of states; this gives rise to a high photoemission intensity. (c) 2006 American Institute of Physics.
    BibTeX:
    @article{Gloskovskii2006,
      author = {Gloskovskii, A. and Nepijko, S. A. and Cinchetti, M. and Schönhense, G. and Fecher, G. H. and Kandpal, H. C. and Felser, C. and Therese, H. A. and Zink, N. and Tremel, W. and Oelsner, A.},
      title = {Time-of-flight photoelectron spectromicroscopy of single MoS2 nanotubes},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {2006},
      volume = {100},
      number = {8},
      pages = {084330},
      doi = {http://dx.doi.org/10.1063/1.2359225}
    }
    
    Kandpal, H.C., Fecher, G.H., Felser, C. & Schönhense, G. Correlation in the transition-metal-based Heusler compounds Co2MnSi and Co2FeSi 2006 Physical Review B
    Vol. 73(9), pp. 094422 
    article DOI  
    Abstract: Half-metallic ferromagnets, such as the Heusler compounds with formula X(2)YZ, are expected to show an integer value for the spin magnetic moment. In contrast to experiments, calculations give noninteger values in certain cases where the compounds are based on X=Co. In order to explain deviations of the magnetic moment calculated for such compounds, the dependence of the electronic structure on the lattice parameter was studied theoretically. In the local density approximation (LDA), the minimum total energy of Co2FeSi is found for the experimental lattice parameter, but the calculated magnetic moment is approximately 12% too low. In addition, half-metallic ferromagnetism and a magnetic moment equal to the experimental value of 6 mu(B) are found only after increasing the lattice parameter by more than 6%. To overcome these discrepancies, the LDA+U scheme was used to respect on-site electron correlation in the calculations. For Co2FeSi, these calculations showed that an effective Coulomb exchange interaction U-eff=U-J in the range of approximately 2-5 eV leads to half-metallic ferromagnetism and to the measured integer magnetic moment at the measured lattice parameter. Finally, it is shown for Co2MnSi that correlation may also serve to destroy the half-metallic behavior if the correlation becomes too strong (above 2 eV for Co2MnSi and above 5 eV for Co2FeSi). These findings indicate that on-site correlation may play an important role in the description of Heusler compounds with localized moments.
    BibTeX:
    @article{Kandpal2006,
      author = {Kandpal, H. C. and Fecher, G. H. and Felser, C. and Schönhense, G.},
      title = {Correlation in the transition-metal-based Heusler compounds Co2MnSi and Co2FeSi},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2006},
      volume = {73},
      number = {9},
      pages = {094422},
      doi = {http://dx.doi.org/10.1103/PhysRevB.73.094422}
    }
    
    Lin, J.Q., Neuhaeusler, U., Slieh, J., Brechling, A., Kleineberg, U., Heinzmann, U., Oelsner, A., Valdaitsev, D., Schönhense, G., Weber, N., Escher, M. & Merkel, M. Actinic extreme ultraviolet lithography mask blank defect inspection by photoemission electron microscopy 2006 Journal Of Vacuum Science & Technology B
    Vol. 24(6), pp. 2631-2635 
    article DOI  
    Abstract: A new method for the actinic inspection of defects inside and on top of extreme ultraviolet (EUV) lithography multi layer-coated mask blanks is presented. The experimental technique is based on photoemission electron microscopy supported by the generation of a standing wave field inside and above the multilayer mask blank when illuminated near the resonance Bragg wavelength at around 13.5 nm. Experimental results on programed defect samples based on electron beam lithographic structures or silica balls overcoated with an EUV multilayer show that buried defects with a lateral size down to 50 nm are detectable. Furthermore, phase structures as shallow as 6 nm in height on a programed phase grating sample have been detected by this technique. The contrast of the phase defect structures has shown to be strongly dependent on and controlled by the phase of the standing wave field at the mask blank surface, and thus can be optimized by tuning the inspection wavelength. (c) 2006 American Vacuum Society.
    BibTeX:
    @article{Lin2006,
      author = {Lin, J. Q. and Neuhaeusler, U. and Slieh, J. and Brechling, A. and Kleineberg, U. and Heinzmann, U. and Oelsner, A. and Valdaitsev, D. and Schönhense, G. and Weber, N. and Escher, M. and Merkel, M.},
      title = {Actinic extreme ultraviolet lithography mask blank defect inspection by photoemission electron microscopy},
      journal = {Journal Of Vacuum Science & Technology B},
      publisher = {A V S Amer Inst Physics},
      year = {2006},
      volume = {24},
      number = {6},
      pages = {2631--2635},
      doi = {http://dx.doi.org/10.1016/j.mee.2007.01.106}
    }
    
    Maul, J., Strachnov, I., Karpuk, S., Bernhard, P., Oelsner, A., Schönhense, G. & Huber, G. Onset of crater formation during short pulse laser ablation 2006 Applied Physics A-Materials Science & Processing
    Vol. 82(1), pp. 43-47 
    article DOI  
    Abstract: We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out.
    BibTeX:
    @article{Maul2006,
      author = {Maul, J. and Strachnov, I. and Karpuk, S. and Bernhard, P. and Oelsner, A. and Schönhense, G. and Huber, G.},
      title = {Onset of crater formation during short pulse laser ablation},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2006},
      volume = {82},
      number = {1},
      pages = {43--47},
      doi = {http://dx.doi.org/10.1007/s00339-005-3357-3}
    }
    
    Maul, J., Berg, T., Marosits, E., Schönhense, G. & Huber, G. Statistical mechanics of fullerene coalescence growth 2006 Physical Review B
    Vol. 74(16), pp. 161406 
    article DOI  
    Abstract: Among the different carbon allotropes fullerenes are exceptionally intriguing for their spheroidal topology out of pentagons and hexagons. However, the dominant formation mode is still ambiguous. Here, we analyze the fullerene formation process by the statistical analysis of fullerene sizes produced in a laser-induced microplasma finding that a simple two-parameter lognormal distribution describes impressively well the cluster frequencies under various conditions. Our findings clearly reveal coalescent growth following a classical collision dynamics and disagree with several earlier assumptions.
    BibTeX:
    @article{Maul2006a,
      author = {Maul, J. and Berg, T. and Marosits, E. and Schönhense, G. and Huber, G.},
      title = {Statistical mechanics of fullerene coalescence growth},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2006},
      volume = {74},
      number = {16},
      pages = {161406},
      doi = {http://dx.doi.org/10.1103/PhysRevB.74.161406}
    }
    
    Neuhäusler, U., Lin, J., Oelsner, A., Schicketanz, M., Valdaitsev, D., Slieh, J., Weber, N., Brzeska, M., Wonisch, A., Westerwalbesloh, T., Brechling, A., Bruckl, H., Escher, M., Merkel, M., Schönhense, G., Kleineberg, U. & Heinzmann, U. A new approach for actinic defect inspection of EUVL multilayer mask blanks: Standing wave photoemission electron microscopy 2006 Microelectronic Engineering
    Vol. 83(4-9), pp. 680-683 
    article DOI  
    Abstract: Extreme ultraviolet lithography (EUVL) at 13.5 nm is the next generation lithography technique capable of printing sub-50 nm structures. With decreasing feature sizes to be printed, the requirements for the lithography mask also become more stringent in terms of defect sizes and densities that are still acceptable and the development of lithography optics has to go along with the development of new mask defect inspection techniques that are fast and offer high resolution (preferable in the range of the minimum feature size) at the same time. We report on the development and experimental results of a new 'at wavelength' full-field imaging technique for defect inspection of multilayer mask blanks for EUV lithography. Our approach uses a photoemission electron microscope (PEEM) in a normal incidence illumination mode at 13 nm to image the photoelectron emission induced by the EUV wave field on the multilayer mask blank surface. We show that by these means, buried defects in the multilayer stack can be probed down to a lateral size of 50 nm, which was the smallest pre-defined structure size under study so far. The PEEMs spatial resolution has been proven to be as small as 29 nm edge slope width in measurements with 250 nm radiation. Therefore, the capability of this technique for actinic measurements at 13 nm radiation is anticipated to be well below 50 nm. (c) 2006 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Neuhaeusler2006,
      author = {Neuhäusler, U. and Lin, J. and Oelsner, A. and Schicketanz, M. and Valdaitsev, D. and Slieh, J. and Weber, N. and Brzeska, M. and Wonisch, A. and Westerwalbesloh, T. and Brechling, A. and Bruckl, H. and Escher, M. and Merkel, M. and Schönhense, G. and Kleineberg, U. and Heinzmann, U.},
      title = {A new approach for actinic defect inspection of EUVL multilayer mask blanks: Standing wave photoemission electron microscopy},
      journal = {Microelectronic Engineering},
      publisher = {Elsevier Science Bv},
      year = {2006},
      volume = {83},
      number = {4-9},
      pages = {680--683},
      doi = {http://dx.doi.org/10.1016/j.mee.2005.12.035}
    }
    
    Neuhäusler, U., Oelsner, A., Slieh, J., Brzeska, M., Wonisch, A., Westerwalbesloh, T., Bruckl, H., Schicketanz, M., Weber, N., Escher, M., Merkel, M., Schönhense, G., Kleineberg, U. & Heinzmann, U. High-resolution actinic defect inspection for extreme ultraviolet lithography multilayer mask blanks by photoemission electron microscopy 2006 Applied Physics Letters
    Vol. 88(5), pp. 053113 
    article DOI  
    Abstract: We report on the development and first experimental results of a "at wavelength" full-field imaging technique for defect inspection of multilayer mask blanks for extreme ultraviolet (EUV) lithography. According to the International Semiconductor Roadmap by Sematech, less than 5x10(-3) defects per cm(2) should be present on such multilayer mask blank to enable mass production of microelectronics using EUV lithography, thus fast high-resolution methods for mask defect inspection and localization are needed. Our approach uses a photoemission electron microscope in a normal incidence illumination mode at 13 nm to image the photoelectron emission induced by the EUV wave field on the multilayer mask blank surface. We show that by these means, buried defects in the multilayer stack can be probed down to a lateral size of 50 nm. (c) 2006 American Institute of Physics.
    BibTeX:
    @article{Neuhaeusler2006a,
      author = {Neuhäusler, U. and Oelsner, A. and Slieh, J. and Brzeska, M. and Wonisch, A. and Westerwalbesloh, T. and Bruckl, H. and Schicketanz, M. and Weber, N. and Escher, M. and Merkel, M. and Schönhense, G. and Kleineberg, U. and Heinzmann, U.},
      title = {High-resolution actinic defect inspection for extreme ultraviolet lithography multilayer mask blanks by photoemission electron microscopy},
      journal = {Applied Physics Letters},
      publisher = {Amer Inst Physics},
      year = {2006},
      volume = {88},
      number = {5},
      pages = {053113},
      doi = {http://dx.doi.org/10.1063/1.2168263}
    }
    
    Schneider, C.M., Krasyuk, A., Nepijko, S.A., Oelsner, A. & Schönhense, G. Accessing fast magnetization dynamics by XPEEM: Status and perspectives 2006 Journal Of Magnetism And Magnetic Materials
    Vol. 304(1), pp. 6-9 
    article DOI  
    Abstract: Being already well established as a versatile technique for high-resolution static magnetic domain imaging, X-ray photoemission electron microscopy (XPEEM) is now also capturing the field of time-resolved magnetic investigations. Using appropriate operation modes at synchrotron radiation sources, a time resolution of 10 ps and less can be achieved in recent magnetodynamics studies, giving access even to phenomena involving precessional processes. (C) 2006 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Schneider2006,
      author = {Schneider, C. M. and Krasyuk, A. and Nepijko, S. A. and Oelsner, A. and Schönhense, G.},
      title = {Accessing fast magnetization dynamics by XPEEM: Status and perspectives},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {2006},
      volume = {304},
      number = {1},
      pages = {6--9},
      doi = {http://dx.doi.org/10.1016/j.jmmm.2006.02.013}
    }
    
    Schönhense, G., Elmers, H.J., Krasyuk, A., Wegelin, F., Nepijko, S.A., Oelsner, A. & Schneider, C.M. Transient spatio-temporal domain patterns in permalloy microstructures induced by fast magnetic field pulses 2006 Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms
    Vol. 246(1), pp. 1-12 
    article DOI  
    Abstract: The response of multidomain flux-closure structures (Landau states) in micrometer-scale magnetic thin-film elements upon fast magnetic field pulses leads to the excitation of magnetic eigenmodes and to short-lived domain patterns that do not occur in quasi-static remagnetisation. Such transient spatio-temporal patterns and particular detail features are discussed. Examples are presented for perm-alloy platelets of various shapes and sizes. Dynamic series of domain patterns with variable delay between field pulse and photon pulse (synchrotron radiation) have been taken using stroboscopic XMCD-PEEM. Precessional remagnetisation starts at the domain boundaries. The damped precessional motion propagates into the domains magnetised perpendicular to the field Pulse. Further, an apparent dynamical broadening of domain boundaries, the formation of transient vortices and domain walls as well as the fast formation of blocking patterns are discussed. An important feature is the action of the demagnetising field that develops via the damped precessional motion of the magnetisation on the nanosecond time scale. The effective field is constituted by the sum of the instantaneous external pulse field and the delayed response of the demagnetising field. (c) 2006 Published by Elsevier B.V.
    BibTeX:
    @article{Schoenhense2006,
      author = {Schönhense, G. and Elmers, H. J. and Krasyuk, A. and Wegelin, F. and Nepijko, S. A. and Oelsner, A. and Schneider, C. M.},
      title = {Transient spatio-temporal domain patterns in permalloy microstructures induced by fast magnetic field pulses},
      journal = {Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms},
      publisher = {Elsevier Science Bv},
      year = {2006},
      volume = {246},
      number = {1},
      pages = {1--12},
      doi = {http://dx.doi.org/10.1016/j.nimb.2005.12.011}
    }
    
    Schönhense, G. & Elmers, H.J. PEEM with high time resolution - imaging of transient processes and novel concepts of chromatic and spherical aberration correction 2006 Surface And Interface Analysis
    Vol. 38(12-13), pp. 1578-1587 
    article DOI  
    Abstract: The potential of time-resolved photoemission electron microscopy (PEEM) for imaging ultrafast processes and for aberration correction in full-field imaging is discussed. In particular, we focus on stroboscopic imaging of precessional magnetic excitations via XMCD-PEEM exploiting the time structure of synchrotron radiation (magnetic field pulse pump-X-ray probe). In a special bunch-compression mode at BESSY, a time resolution of about 15 ps has been obtained. Further, we discuss an all-optical pump-probe technique using femtosecond laser excitation. A highly promising alternative to stroboscopic imaging is an approach using time-resolved image detection. As a second application of time-resolved PEEM we discuss potential ways of aberration correction. These approaches go back to the old ideas of Scherzer in the light of state-of-the-art equipment. The excellent time structure of synchrotron radiation or pulsed lasers along with advanced methods of time-resolved image detection and fast electronic pulsers opens ways for driving the resolution limit of a PEEM into the range of a few nanometers. Copyright (C) 2006 John Wiley & Sons, Ltd.
    BibTeX:
    @article{Schoenhense2006a,
      author = {Schönhense, G. and Elmers, H. J.},
      title = {PEEM with high time resolution - imaging of transient processes and novel concepts of chromatic and spherical aberration correction},
      journal = {Surface And Interface Analysis},
      publisher = {John Wiley & Sons Ltd},
      year = {2006},
      volume = {38},
      number = {12-13},
      pages = {1578--1587},
      doi = {http://dx.doi.org/10.1002/sia.2433}
    }
    
    Schönhense, G., Elmers, H.J., Nepijko, S.A. & Schneider, C.M. Time Resolved Photoemission Electron Microscopy 2006 Advances in Imaging And Electron Physics, pp. 159-323  incollection URL 
    BibTeX:
    @incollection{Schoenhense2006b,
      author = {Schönhense, G. and Elmers, H. J. and Nepijko, S. A. and Schneider, C. M.},
      title = {Time Resolved Photoemission Electron Microscopy},
      booktitle = {Advances in Imaging And Electron Physics},
      publisher = {Elsevier Academic Press Inc},
      year = {2006},
      pages = {159--323},
      url = {http://books.google.com/books?hl=en&lr=&id=JJbBhmYVhb8C&oi=fnd&pg=PA159&dq=Sch%C3%B6nhense,+G.+and+Elmers,+H.+J.+and+Nepijko,+S.+A.+and+Schneider,+C.+M.&ots=wMJUxLMzIa&sig=dCiXi7RYrzFYhETB471a29KCWzE}
    }
    
    Wurmehl, S., Fecher, G.H., Kroth, K., Kronast, F., Durr, H.A., Takeda, Y., Saitoh, Y., Kobayashi, K., Lin, H.J., Schönhense, G. & Felser, C. Electronic structure and spectroscopy of the quaternary Heusler alloy Co2Cr1-xFexAl 2006 Journal Of Physics D-Applied Physics
    Vol. 39(5), pp. 803-815 
    article DOI  
    Abstract: Quaternary Heusler alloys Co2Cr1-xFexAl with varying Cr to Fe ratio x were investigated experimentally and theoretically. The electronic structure and spectroscopic properties were calculated using the full relativistic Korringa-Kohn-Rostocker method with coherent potential approximation to account for the random distribution of Cr and Fe atoms as well as random disorder. Magnetic effects are included using spin dependent potentials in the local spin density approximation. Magnetic circular dichroism in x-ray absorption was measured at the L-2,L-3 edges of Co, Fe and Cr of the pure compounds and the x = 0.4 alloy in order to determine element specific magnetic moments. Calculations and measurements show an increase of the magnetic moments with increasing, iron content. Resonant (560-800eV) soft x-ray as well as high resolution-high energy (>= 3.5 keV) hard x-ray photo emission was used to probe the density of the Occupied states in Co2Cr0.6Fe0.4Al.
    BibTeX:
    @article{Wurmehl2006,
      author = {Wurmehl, S. and Fecher, G. H. and Kroth, K. and Kronast, F. and Durr, H. A. and Takeda, Y. and Saitoh, Y. and Kobayashi, K. and Lin, H. J. and Schönhense, G. and Felser, C.},
      title = {Electronic structure and spectroscopy of the quaternary Heusler alloy Co2Cr1-xFexAl},
      journal = {Journal Of Physics D-Applied Physics},
      publisher = {Iop Publishing Ltd},
      year = {2006},
      volume = {39},
      number = {5},
      pages = {803--815},
      doi = {http://dx.doi.org/10.1088/0022-3727/39/5/S06}
    }
    
    Bernhard, P., Ziethen, C., Schönhense, G., Schreck, M., Bauer, T., Gsell, S. & Stritzker, B. Structural properties of the diamond nucleation layer on iridium analyzed by laterally resolved X-ray absorption spectroscopy 2006 Japanese Journal Of Applied Physics Part 2-Letters & Express Letters
    Vol. 45(33-36), pp. L984-L986 
    article DOI  
    Abstract: The complex structure of the diamond nucleation layer on iridium has been studied by X-ray absorption near edge structure (XANES) in combination with X-ray photoemission electron microscopy (X-PEEM). In contrast to all other substrate materials, on iridium the diamond nuclei formed by the bias enhanced nucleation (BEN) procedure gather in islands ("domains") with micron-size lateral dimensions. Laterally resolved XANES spectra of the carbon-K absorption edge clearly show the difference in carbon bonding structure Outside and inside the domain area. A positive feedback mechanism for the nucleation and lateral crystal growth, are two alternative concepts which can explain the domain formation.
    BibTeX:
    @article{,
      author = {Bernhard, P. and Ziethen, C. and Schönhense, G. and Schreck, M. and Bauer, T. and Gsell, S. and Stritzker, B.},
      title = {Structural properties of the diamond nucleation layer on iridium analyzed by laterally resolved X-ray absorption spectroscopy},
      journal = {Japanese Journal Of Applied Physics Part 2-Letters & Express Letters},
      publisher = {Inst Pure Applied Physics},
      year = {2006},
      volume = {45},
      number = {33-36},
      pages = {L984--L986},
      doi = {http://dx.doi.org/10.1143/JJAP.45.L984}
    }
    
    Cinchetti, M. & Schönhense, G. Two-photon photoemission spectromicroscopy of noble metal clusters on surfaces studied using time-of-flight photoemission electron microscopy 2005 Journal Of Physics-Condensed Matter
    Vol. 17(16), pp. S1319-S1328 
    article DOI  
    Abstract: Time-of-flight two-photon photoemission spectromicroscopy was used to investigate Cu surface inhomogeneities and Ag cluster films deposited on a Si(111) substrate. Femtosecond laser radiation with wavelength around 400 nm (photon energy 3.1 eV) was used for excitation. The metal aggregates have linear dimensions in the range between 40 nm and several 100 nm. It is shown that the two-photon photoemission spectra of the Cu and Ag nanoclusters reveal the same qualitative differences from the spectra of the corresponding homogeneous and clean metal surfaces. In particular, they show an enhanced photoemission yield (up to 70 times higher) and present a different overall shape, characterized by differences around the Fermi level onset and a steeper intensity increase at lower final state energies. These differences are discussed in terms of the excitation of localized surface plasmons in the clusters and a resulting modification of the near-zone electromagnetic field, which in turn influences the two-photon photoemission and its dynamics. Moreover, it is shown that a positive unit charge (photohole) resides on the clusters during the timescale relevant for the two-photon photoemission process.
    BibTeX:
    @article{Cinchetti2005,
      author = {Cinchetti, M. and Schönhense, G.},
      title = {Two-photon photoemission spectromicroscopy of noble metal clusters on surfaces studied using time-of-flight photoemission electron microscopy},
      journal = {Journal Of Physics-Condensed Matter},
      publisher = {Iop Publishing Ltd},
      year = {2005},
      volume = {17},
      number = {16},
      pages = {S1319--S1328},
      doi = {http://dx.doi.org/10.1088/0953-8984/17/16/003}
    }
    
    Cinchetti, M., Gloskovskii, A., Nepjiko, S.A., Schönhense, G., Rochholz, H. & Kreiter, M. Photoemission electron microscopy as a tool for the investigation of optical near fields 2005 Physical Review Letters
    Vol. 95(4), pp. 047601 
    article DOI  
    Abstract: Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiOx). Photoemission was induced by illumination with a Hg UV lamp (photon energy cutoff h omega(UV)=5.0 eV, wavelength lambda(UV)=250 nm) and with a Ti:sapphire femtosecond laser (h omega(l)=3.1 eV, lambda(l)=400 nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signature of the local electrical field therefore providing a tool to map the optical near field with the resolution of emission electron microscopy.
    BibTeX:
    @article{Cinchetti2005a,
      author = {Cinchetti, M. and Gloskovskii, A. and Nepjiko, S. A. and Schönhense, G. and Rochholz, H. and Kreiter, M.},
      title = {Photoemission electron microscopy as a tool for the investigation of optical near fields},
      journal = {Physical Review Letters},
      publisher = {American Physical Soc},
      year = {2005},
      volume = {95},
      number = {4},
      pages = {047601},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.95.047601}
    }
    
    Escher, M., Weber, N., Merkel, M., Kromker, B., Funnemann, D., Schmidt, S., Reinert, F., Forster, F., Hufner, S., Bernhard, P., Ziethen, D., Elmers, H.J. & Schönhense, G. NanoESCA: Imaging UPS and XPS with high energy resolution 2005 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 144, pp. 1179-1182 
    article DOI  
    Abstract: A novel imaging electron spectrometer has been used for laterally resolved ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) in the soft X-ray range. The instrument is based on a high-resolution emission microscope optics using a cathode lens and an imaging dispersive analyser. The analyser is corrected for the leading aberration term (alpha(2)-term) by means of two hemispherical analysers in antisymmetric configuration with an appropriate transfer lens. Small-area spectra as well as energy-filtered images have been taken in the soft X-ray range for a meteorite sample and in the range of the d-band of a Cu polycrystal. An energy resolution of 106 meV along with a high spatial resolution allows a detailed analysis of trace elements in the meteorite sample as well as local UPS spectra of the surface of the Cu sample. (c) 2005 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Escher2005,
      author = {Escher, M. and Weber, N. and Merkel, M. and Kromker, B. and Funnemann, D. and Schmidt, S. and Reinert, F. and Forster, F. and Hufner, S. and Bernhard, P. and Ziethen, D. and Elmers, H. J. and Schönhense, G.},
      title = {NanoESCA: Imaging UPS and XPS with high energy resolution},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2005},
      volume = {144},
      pages = {1179--1182},
      doi = {http://dx.doi.org/10.1016/j.elspec.2005.01.250}
    }
    
    Escher, M., Weber, N., Merkel, M., Ziethen, C., Bernhard, P., Schönhense, G., Schmidt, S., Forster, F., Reinert, F., Krömker, B. & Funnemann, D. NanoESCA: a novel energy filter for imaging x-ray photoemission spectroscopy 2005 Journal of Physics Condensed Matter
    Vol. 17, pp. 1329-+ 
    article DOI  
    Abstract: A novel instrument for imaging ESCA is described. It is based on a tandem arrangement of two hemispherical energy analysers used as an imaging energy filter. The main spherical aberration (α2-term) of the analyser is corrected by the antisymmetry of the tandem configuration. The kinetic energy range useable for imaging extends up to 1.6 keV; this is compatible with Mg and Al Kα laboratory x-ray sources. First experiments on the chemical surface composition of a Cu0.98Bi0.02 polycrystal, a GaAs/AlGaAs heterostructure and Ag crystallites on Si(111) have been performed using synchrotron radiation. The results reveal an energy resolution of 190 meV and a lateral resolution (edge resolution) of 120 nm. Besides elimination of the analyser's spherical aberration, the tandem arrangement largely retains the time structure of the electron signal, unlike a single hemispherical analyser.
    BibTeX:
    @article{Escher2005a,
      author = {Escher, M. and Weber, N. and Merkel, M. and Ziethen, C. and Bernhard, P. and Schönhense, G. and Schmidt, S. and Forster, F. and Reinert, F. and Krömker, B. and Funnemann, D.},
      title = {NanoESCA: a novel energy filter for imaging x-ray photoemission spectroscopy},
      journal = {Journal of Physics Condensed Matter},
      year = {2005},
      volume = {17},
      pages = {1329-+},
      doi = {http://dx.doi.org/10.1088/0953-8984/17/16/004}
    }
    
    Fecher, G.H., Kandpal, H.C., Wurmehl, S., Morais, J., Lin, H.J., Elmers, H.J., Schönhense, G. & Felser, C. Design of magnetic materials: the electronic structure of the ordered, doped Heusler compound Co2Cr1-xFexAl 2005 Journal Of Physics-Condensed Matter
    Vol. 17(46), pp. 7237-7252 
    article DOI  
    Abstract: The doped Hensler compounds CO2Cr1-xFexAl with varying Cr to Fe ratio x were investigated experimentally and theoretically. The electronic structure of the ordered, doped Heusler compound Co2Cr1-xFe Al (x = n/4, n = 0, 1, 2, 3, 4) was calculated using band structure calculations of different types. The ordered compounds turned out to be ferromagnetic with the small Al magnetic moment aligned antiparallel to the 3d transition metal moments. All compounds show a gap around the Fermi energy in the minority bands. The pure compounds exhibit an indirect minority gap, whereas the ordered, doped compounds exhibit a direct gap. The magnetic circular dichroism in the x-ray absorption spectra was measured at the L-2,L-3 edges of Co, Fe, and Cr of the pure compounds and the x = 0.4 alloy in order to determine element-specific magnetic moments. Calculations and measurements show an increase of the magnetic moments with increasing iron content. The experimentally observed reduction of the magnetic moment of Cr can be explained by Co-Cr site disorder. The presence of the gap in the minority bands Of Co2CrAl can be attributed to the occurrence of pure Co-2 and mixed CrAl(001) planes in the L2(1) structure. It is retained in structures with different order of the CrAl planes but vanishes in the X structure with alternating CoCr and CoAl planes.
    BibTeX:
    @article{Fecher2005,
      author = {Fecher, G. H. and Kandpal, H. C. and Wurmehl, S. and Morais, J. and Lin, H. J. and Elmers, H. J. and Schönhense, G. and Felser, C.},
      title = {Design of magnetic materials: the electronic structure of the ordered, doped Heusler compound Co2Cr1-xFexAl},
      journal = {Journal Of Physics-Condensed Matter},
      publisher = {Iop Publishing Ltd},
      year = {2005},
      volume = {17},
      number = {46},
      pages = {7237--7252},
      doi = {http://dx.doi.org/10.1088/0953-8984/17/46/008}
    }
    
    Klais, M., Gundel, H.W. & Schönhense, G. Energy-resolved analysis of ferroelectric electron emission from TGS using emission electron microscopy 2005 Applied Physics A-Materials Science & Processing
    Vol. 80(3), pp. 545-549 
    article DOI  
    Abstract: Ferroelectric electron emission arises when the spontaneous polarization of a ferroelectric is switched due to the application of an electric field. In order to study the origin of emission and the related emission mechanism, space-resolved emission electron microscopy has been employed. The integral energy distribution of the emitted electrons from triglycine-sulfate surfaces has been investigated using a cylindrical sector analyzer and an imaging retarding field analyzer. Space-resolved emission photography and energy distribution measurements were obtained, revealing the effect of ferroelectric switching on the electric field distribution and hence on the emission process. Evidence of secondary electron emission from the metal electrodes has been found.
    BibTeX:
    @article{Klais2005,
      author = {Klais, M. and Gundel, H. W. and Schönhense, G.},
      title = {Energy-resolved analysis of ferroelectric electron emission from TGS using emission electron microscopy},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2005},
      volume = {80},
      number = {3},
      pages = {545--549},
      doi = {http://dx.doi.org/10.1007/s00339-004-2984-4}
    }
    
    Krasyuk, A., Wegelin, F., Nepijko, S.A., Elmers, H.J., Schönhense, G., Bolte, M. & Schneider, C.M. Self-trapping of magnetic oscillation modes in Landau flux-closure structures 2005 Physical Review Letters
    Vol. 95(20), pp. 207201 
    article DOI  
    Abstract: We investigated the magnetodynamics in rectangular Permalloy platelets by means of time-resolved x-ray photoemission microscopy. 10 nm thick platelets of 16x32 mu m size were excited by an oscillatory field along the short side of the sample with a fundamental frequency of 500 MHz and considerable contributions of higher harmonics. Under the influence of the oscillatory field, the Neel wall in the initial classical Landau pattern shifts away from the center, corresponding to an induced magnetic moment perpendicular to the exciting field. This phenomenon is explained by a self-trapping effect of the dominating spin-wave mode when the system is excited just below the resonance frequency. The basic driving mechanism is the maximization of entropy.
    BibTeX:
    @article{Krasyuk2005,
      author = {Krasyuk, A. and Wegelin, F. and Nepijko, S. A. and Elmers, H. J. and Schönhense, G. and Bolte, M. and Schneider, C. M.},
      title = {Self-trapping of magnetic oscillation modes in Landau flux-closure structures},
      journal = {Physical Review Letters},
      publisher = {American Physical Soc},
      year = {2005},
      volume = {95},
      number = {20},
      pages = {207201},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.95.207201}
    }
    
    Martyanov, O.N., Yudanov, V.F., Lee, R.N., Nepijko, S.A., Elmers, H.J., Schneider, C.M. & Schönhense, G. Ferromagnetic resonance investigation of collective phenomena in two-dimensional periodic arrays of Co particles 2005 Applied Physics A-Materials Science & Processing
    Vol. 81(4), pp. 679-683 
    article DOI  
    Abstract: The ferromagnetic resonance (FMR) method is used to study the collective phenomena in two-dimensional periodic arrays of disk-shaped Co particles. A study of geometrically similar structures with different periods reveals a broadening of the FMR resonance lines due to the excitation of additional size-dependent non-uniform spin waves. It is shown that these collective spin-wave modes are based on dipole-dipole interactions between the ferromagnetic particles in the array. Qualitative and quantitative data on magnetic interparticle interactions can thus be obtained from FMR spectra for two-dimensional periodic arrays of ferromagnetic particles.
    BibTeX:
    @article{Martyanov2005,
      author = {Martyanov, O. N. and Yudanov, V. F. and Lee, R. N. and Nepijko, S. A. and Elmers, H. J. and Schneider, C. M. and Schönhense, G.},
      title = {Ferromagnetic resonance investigation of collective phenomena in two-dimensional periodic arrays of Co particles},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2005},
      volume = {81},
      number = {4},
      pages = {679--683},
      doi = {http://dx.doi.org/10.1007/s00339-005-3250-0}
    }
    
    Maul, J., Strachnov, I., Karpuk, S., Schilling, T., Oelsner, A., Bernhard, P., Elmers, H.J., Schönhense, G. & Huber, G. Periodic unmixing of a binary metallic vapor 2005 Physical Review B
    Vol. 72(15), pp. 155431 
    article DOI  
    Abstract: We report on a type of surface structuring after short pulse laser ablation of a binary alloy. We observe the emergence of a concentric ring structure with changing elemental composition. The composition changes are interpreted by condensation of the ambient ablation vapor due to stress wave excitations in the ablation spot.
    BibTeX:
    @article{Maul2005,
      author = {Maul, J. and Strachnov, I. and Karpuk, S. and Schilling, T. and Oelsner, A. and Bernhard, P. and Elmers, H. J. and Schönhense, G. and Huber, G.},
      title = {Periodic unmixing of a binary metallic vapor},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2005},
      volume = {72},
      number = {15},
      pages = {155431},
      doi = {http://dx.doi.org/10.1103/PhysRevB.72.155431}
    }
    
    Neeb, D., Krasyuk, A., Oelsner, A., Nepijko, S.A., Elmers, H.J., Kuksov, A., Schneider, C.M. & Schönhense, G. Sub-nanosecond resolution x-ray magnetic circular dichroism photoemission electron microscopy of magnetization processes in a permalloy ring 2005 Journal Of Physics-Condensed Matter
    Vol. 17(16), pp. S1381-S1395 
    article DOI  
    Abstract: yFast magnetization processes in a microstructured permalloy ring with 80 &mu; m o.d. and 30 nm thickness have been observed by photoemission electron microscopy exploiting x-ray magnetic circular dichroism as the magnetic contrast mechanism. As a high speed probe we employed synchrotron radiation pulses at the ESRF (Grenoble) operated in 16-bunch mode, yielding photon pulses of 105 ps FWHM with a period of 176 ns. Fast magnetic field pulses have been generated by means of current pulses through coplanar waveguides with the magnetic structure being lithographically prepared on their surface. A stroboscopic pump-probe set-up with a variable time delay between the field pulse and photon pulse allowed us to take snapshots of the dynamic response of the magnetic domain structure. We observed coherent magnetization rotation during the leading edge part of the field pulse, the formation of a characteristic domain pattern ('onion state') in the plateau region of the pulse and the fast formation of a striped domain pattern (incoherent magnetization rotation) during the trailing edge part of the field pulse. A numerical simulation confirmed essential features of the stroboscopic image series.
    BibTeX:
    @article{Neeb2005,
      author = {Neeb, D. and Krasyuk, A. and Oelsner, A. and Nepijko, S. A. and Elmers, H. J. and Kuksov, A. and Schneider, C. M. and Schönhense, G.},
      title = {Sub-nanosecond resolution x-ray magnetic circular dichroism photoemission electron microscopy of magnetization processes in a permalloy ring},
      journal = {Journal Of Physics-Condensed Matter},
      publisher = {Iop Publishing Ltd},
      year = {2005},
      volume = {17},
      number = {16},
      pages = {S1381--S1395},
      doi = {http://dx.doi.org/10.1088/0953-8984/17/16/009}
    }
    
    Nepijko, S.A., Sedov, N.N. & Schönhense, G. Measurement of electric fields on object surface in an emission electron microscope 2005 Advances In Imaging And Electron Physics
    Vol. 136, pp. 227-316 
    article  
    BibTeX:
    @article{Nepijko2005,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G.},
      title = {Measurement of electric fields on object surface in an emission electron microscope},
      journal = {Advances In Imaging And Electron Physics},
      publisher = {Elsevier Academic Press Inc},
      year = {2005},
      volume = {136},
      pages = {227--316}
    }
    
    Oelsner, A., Krasyuk, A., Nepijko, S., Schneider, C.M. & Schönhense, G. Spatially resolved observation of dynamics in electrical and magnetic field distributions by means of a delayline detector and PEEM 2005 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 144, pp. 771-776 
    article DOI  
    Abstract: Photoemission electron microscopy (PEEM) was exploited to observe the dynamics in local field distributions on microstrip-line devices with a best time resolution of 133 ps. A delayline detector system served as imaging unit capable of a time resolving data acquisition and processing. The setup can be operated at the resolution limit of the PEEM of about 20 nm while a continuously illuminating UV-lamp excites the photoelectrons in threshold photoemission. A pulsed photon source is not needed to obtain time resolved images, the time reference of the data acquisition was taken by a periodic signal (clock, here typ. 100 MHz) in phase with the pulse pattern applied to the microstrip-line device. Ultra-short current pulses passing the microstrip-line are associated with local changes of the magnetic field at the device surface and with a fast propagation of the electrical potential as well. The photoelectron imaging is immediately responding to small local field distortions due to the small kinetic energy of the electrons escaping from the surface. Thus, local field distortions can be detected as temporal changes between the 133 ps wide image-slices which are sorted by time in reference to the clock signal. (c) 2005 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Oelsner2005,
      author = {Oelsner, A. and Krasyuk, A. and Nepijko, S. and Schneider, C. M. and Schönhense, G.},
      title = {Spatially resolved observation of dynamics in electrical and magnetic field distributions by means of a delayline detector and PEEM},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2005},
      volume = {144},
      pages = {771--776},
      doi = {http://dx.doi.org/10.1016/j.elspec.2005.01.280}
    }
    
    Ott, U., Sudek, C., Maul, J., Bernhard, P., Elmers, H.J. & Schönhense, G. Nano-ESCA: A Valuable Tool for Studying Presolar Grains (and Other Extraterrestrial Materials) 2005 36th Annual Lunar and Planetary Science Conference, pp. 1294-+  inproceedings URL 
    BibTeX:
    @inproceedings{Ott2005,
      author = {Ott, U. and Sudek, C. and Maul, J. and Bernhard, P. and Elmers, H.~J. and Schönhense, G.},
      title = {Nano-ESCA: A Valuable Tool for Studying Presolar Grains (and Other Extraterrestrial Materials)},
      booktitle = {36th Annual Lunar and Planetary Science Conference},
      year = {2005},
      pages = {1294-+},
      url = {http://adsabs.harvard.edu/abs/2005LPI....36.1294O}
    }
    
    Schneider, C.M., Kuksov, A., Krasyuk, A., Oelsner, A., Nepijko, S.A. & Schönhense, G. Time-resolved X-ray photoemission electron microscopy: imaging magnetodynamics on the 100 ps scale and below 2005 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 144, pp. 967-971 
    article DOI  
    Abstract: We present recent results of time-resolved X-ray photoemission electron microscopy (TR-XPEEM) investigations on magnetic systems. Our studies of microstructured permalloy particles employ a magnetic pump XPEEM probe approach. The stroboscopic experiments feature a time resolution of Delta tau <= 130ps and yield magnetic domain images with a surprising richness of details. We observe a strong influence of incoherent magnetization rotation processes, which lead to complicated transient domain structures with a blocked relaxation behavior. (c) 2005 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Schneider2005,
      author = {Schneider, C. M. and Kuksov, A. and Krasyuk, A. and Oelsner, A. and Nepijko, S. A. and Schönhense, G.},
      title = {Time-resolved X-ray photoemission electron microscopy: imaging magnetodynamics on the 100 ps scale and below},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2005},
      volume = {144},
      pages = {967--971},
      doi = {http://dx.doi.org/10.1016/j.elspec.2005.01.261}
    }
    
    Valdaitsev, D.A., Kukunin, A., Prokop, J., Elmers, H.J. & Schönhense, G. Growth and magnetic properties of ultra-thin Co(0001) films on patterned Mo(110)/Al2O3(11(2)) substrates 2005 Applied Physics A-Materials Science & Processing
    Vol. 80(4), pp. 731-734 
    article DOI  
    Abstract: Single crystalline patterned Mo(110) films have been prepared on Al2O3(1120) using standard lithographical techniques, that can be used as a substrate for 3d magnetic metals epitaxy. The preparation procedure, and the structural and morphological characteristics are presented. We show that the patterned Mo( 110) films may be used in a similar way than single crystal Mo( 110) substrates. The structural and magnetic properties of a 3 nm-thick cobalt film deposited on the patterned Mo( 110) film have been studied. The epitaxial Co layer reveals a uniaxial in-plane magnetic anisotropy as measured by Kerr magnetometry.
    BibTeX:
    @article{Valdaitsev2005,
      author = {Valdaitsev, D. A. and Kukunin, A. and Prokop, J. and Elmers, H. J. and Schönhense, G.},
      title = {Growth and magnetic properties of ultra-thin Co(0001) films on patterned Mo(110)/Al2O3(11(2)) substrates},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2005},
      volume = {80},
      number = {4},
      pages = {731--734},
      doi = {http://dx.doi.org/10.1007/s00339-004-3137-5}
    }
    
    Bernhard, P., Ziethen, C., Ohr, R., Hilgers, H. & Schönhense, G. Investigations of the corrosion protection of ultrathin a-C and a-C:N overcoats for magnetic storage devices 2004 Surface and Coatings Technology
    Vol. 180-181, pp. 621-626 
    article DOI  
    Abstract: The thickness-dependent corrosion protection of carbon overcoats for magnetic hard disks can be analyzed by collecting X-ray absorption near edge structure (XANES) spectra at the Co L3-edge. Co is the main constituent of the protected magnetic media underneath. The spectra of the Co absorption edge display a strong peak for pure metallic, non-oxidized Co. This peak splits up into several sub-structures for oxidized Co. Therefore, XANES spectra provide a straightforward method to determine the overcoat thickness, leading to closed coverage and corrosion protection of the underlying material. A similar approach was carried out by X-ray photoelectron spectroscopy (XPS). Standard a-C:N overcoats deposited by magnetron sputtering (MS) were compared to a-C overcoats deposited by a novel filtered high current pulsed arc source (HCA) using a highly resolved imaging XPS system providing the combined measurement of XANES and XPS spectra in the same field of view. We determined that the HCA deposited a-C overcoats provide a closed coverage down to a layer thickness of 1.4 nm, whereas standard MS a-C:N overcoats do not cover the magnetic film completely until a thickness of 2-3 nm is reached.
    BibTeX:
    @article{Bernhard2004,
      author = {Bernhard, P. and Ziethen, Ch. and Ohr, R. and Hilgers, H. and Schönhense, G.},
      title = {Investigations of the corrosion protection of ultrathin a-C and a-C:N overcoats for magnetic storage devices},
      journal = {Surface and Coatings Technology},
      year = {2004},
      volume = {180-181},
      pages = {621--626},
      doi = {http://dx.doi.org/10.1016/j.surfcoat.2003.10.106}
    }
    
    Cinchetti, M., Valdaitsev, D.A., Gloskovskii, A., Oelsner, A., Nepijko, S.A. & Schönhense, G. Photoemission time-of-flight spectromicroscopy of Ag nanoparticle films on Si(111) 2004 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 137-40, pp. 249-257 
    article DOI  
    Abstract: Time-of-flight photoemission electron microscopy was used to measure spatially resolved energy distribution curves of electrons emitted from Ag nanoparticle films with different mass thicknesses. Two-photon photoemission (2PPE) was induced by femtosecond laser pulse excitation with 3.1 eV photon energy and 200 fs pulse width. Regions of Ag nanoparticles with different average sizes and one region with a continuous 100 nm thick Ag film were deposited as a stepped wedge on a Si(1 1 1) substrate. Upon laser excitation the nanoparticle films exhibit a very high electron emission yield in the images, whereas the uncovered Si surface and the continuous Ag film are dark. The time-of-flight electron spectra obtained from the nanoparticle films are remarkably different from the spectra of the continuous film, well-known from literature. The nanoparticle spectra are up to a factor of 160 more intense than the spectrum of the continuous film. They reveal different widths, overall shape and a shift and broadening of the Fermi edge. The results are discussed in terms of Mie plasmon assisted two-photon photoemission of the nanoparticles. (C) 2004 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Cinchetti2004,
      author = {Cinchetti, M. and Valdaitsev, D. A. and Gloskovskii, A. and Oelsner, A. and Nepijko, S. A. and Schönhense, G.},
      title = {Photoemission time-of-flight spectromicroscopy of Ag nanoparticle films on Si(111)},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {137-40},
      pages = {249--257},
      doi = {http://dx.doi.org/10.1016/j.elspec.2004.02.052}
    }
    
    Elmers, H., Wurmehl, S., Fecher, G.H., Jakob, G., Felser, C. & Schönhense, G. Enhanced orbital magnetic moments in the heusler compounds Co2CrAl, Co2Cr0.6Fe0.4Al, Co2FeAl 2004 Journal Of Magnetism And Magnetic Materials
    Vol. 272-76, pp. 758-759 
    article DOI  
    Abstract: Using the magnetic circular dichroism in X-ray absorption at the L-2,L-3-edges of the 3d-transition metals, we determined the element specific ratio between orbital and spin magnetic moment of the Heusler compounds Co2CrAl, Co2Cr0.6Fe0.4Al and Co2FeAl. The orbital magnetic moment per spin is large (0.1-0.2) compared to bulk values of Fe and Co metals. (C) 2004 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Elmers2004,
      author = {Elmers, H. and Wurmehl, S. and Fecher, G. H. and Jakob, G. and Felser, C. and Schönhense, G.},
      title = {Enhanced orbital magnetic moments in the heusler compounds Co2CrAl, Co2Cr0.6Fe0.4Al, Co2FeAl},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {272-76},
      pages = {758--759},
      doi = {http://dx.doi.org/10.1016/j.jmmm.2003.12.1086}
    }
    
    Elmers, H.J., Wurmehl, S., Fecher, G.H., Jakob, G., Felser, C. & Schönhense, G. Field dependence of orbital magnetic moments in the Heusler compounds Co2FeAl and Co2Cr0.6Fe0.4Al 2004 Applied Physics A-Materials Science & Processing
    Vol. 79(3), pp. 557-563 
    article DOI  
    Abstract: Orbital and spin magnetic moments of the Heusler compounds Co2FeAl and Co2Cr0.6Fe0.4Al were measured by magnetic circular dichroism in X-ray absorption (XMCD). The orbital magnetic moments per spin are quite large (0.1-0.2) compared to bulk values of Fe and Co metals, indicating a considerable spin-orbit coupling in these Heusler compounds. A strong localization of the 3d electron states might be responsible for this observation. The Co and Fe orbital to spin moment ratio shows a distinct decrease of Deltar(Fe) = 0.04 +/- 0.02 and Deltar(Co) = 0.06 +/- 0.02 with increasing external field for the ternary compound Co2FeAl, while the ratio is within error limits independent of the field for Co2Cr0.6Fe0.4Al. This is discussed in terms of a relation to magnetocrystalline anisotropies.
    BibTeX:
    @article{Elmers2004a,
      author = {Elmers, H. J. and Wurmehl, S. and Fecher, G. H. and Jakob, G. and Felser, C. and Schönhense, G.},
      title = {Field dependence of orbital magnetic moments in the Heusler compounds Co2FeAl and Co2Cr0.6Fe0.4Al},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2004},
      volume = {79},
      number = {3},
      pages = {557--563},
      doi = {http://dx.doi.org/10.1007/s00339-003-2366-3}
    }
    
    Gloskovskii, A., Valdaitsev, D., Nepijko, S.A., Sedov, N.N. & Schönhense, G. Electrical and emission properties of current-carrying silver cluster films detected by an emission electron microscope 2004 Applied Physics A-Materials Science & Processing
    Vol. 79(3), pp. 707-712 
    article DOI  
    Abstract: Silver cluster films deposited on glass or sapphire have been investigated using an emission electron microscope when a voltage was applied across the film. The electric field distribution in the silver cluster film was measured exploiting the image distortion with increasing voltage. The electron and photon emission originating from the cluster film was visualized. The latter phenomena are correlated with a deviation from Ohmic behavior of the conductivity curve.
    BibTeX:
    @article{Gloskovskii2004,
      author = {Gloskovskii, A. and Valdaitsev, D. and Nepijko, S. A. and Sedov, N. N. and Schönhense, G.},
      title = {Electrical and emission properties of current-carrying silver cluster films detected by an emission electron microscope},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2004},
      volume = {79},
      number = {3},
      pages = {707--712},
      doi = {http://dx.doi.org/10.1007/s00339-003-2318-y}
    }
    
    Klais, M., Averty, D., Gundel, H.W. & Schönhense, G. Visualization of field induced ferroelectric electron emission from TGS using emission electron microscopy 2004 Applied Physics A-Materials Science & Processing
    Vol. 78(1), pp. 67-72 
    article DOI  
    Abstract: Field induced electron emission from triglycinesulfate (TGS) has been investigated using parallel imaging electron emission microscopy (EEM). The emission phenomenon has been induced by applying an ac electrical field up to 2 kV/mm to a single crystal of approximately 0.1 mm thickness. Emission patterns have been observed as a function of the applied field amplitude and of the crystal temperature. At voltages below the coercive field, no emission is visible. When approaching the Curie temperature, emission gradually disappears. This indicates an electron emission mechanism relying on the existence of a switchable ferroelectric phase. The information content of the images is discussed, an interpretation is given on the basis of existing theories.
    BibTeX:
    @article{Klais2004,
      author = {Klais, M. and Averty, D. and Gundel, H. W. and Schönhense, G.},
      title = {Visualization of field induced ferroelectric electron emission from TGS using emission electron microscopy},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer-Verlag},
      year = {2004},
      volume = {78},
      number = {1},
      pages = {67--72},
      doi = {http://dx.doi.org/10.1007/s00339-003-2219-0}
    }
    
    Krasyuk, A., Oelsner, A., Nepijko, S.A., Sedov, N.N., Kuksov, A., Schneider, C.M. & Schönhense, G. Dynamics of magnetic stray fields at initial stage of magnetization reversal of micrometer-sized Co dots 2004 Applied Physics A-Materials Science & Processing
    Vol. 79(8), pp. 1925-1930 
    article DOI  
    Abstract: The dynamical evolution of magnetic stray fields has been investigated at the initial stage of magnetization reversal of a microstructured cobalt film (Co dots). Quantitative measurements of the domain magnetization and of the shift of the domain boundaries have been performed at Ins intervals. The measurements were performed using an emission electron microscope. The photoelectrons were excited from a sample using well-defined synchrotron-radiation pulses in single bunch operation mode (UE56/1-PGM at BESSY II, Berlin). The magnetization movement was initiated by an external magnetic field pulse, the pulse width being 8 ns. The magnetic field pulse was synchronized with the synchrotron single bunch radiation pulses. The lateral and time resolutions of the applied pulses were 50 nm and 500 ps, respectively.
    BibTeX:
    @article{Krasyuk2004,
      author = {Krasyuk, A. and Oelsner, A. and Nepijko, S. A. and Sedov, N. N. and Kuksov, A. and Schneider, C. M. and Schönhense, G.},
      title = {Dynamics of magnetic stray fields at initial stage of magnetization reversal of micrometer-sized Co dots},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2004},
      volume = {79},
      number = {8},
      pages = {1925--1930},
      doi = {http://dx.doi.org/10.1007/s00339-004-2637-7}
    }
    
    Kuksov, A., Schneider, C.M., Oelsner, A., Krasyuk, A., Neeb, D., Schönhense, G., De Nadai, C. & Brookes, N.B. Investigating magnetization dynamics in permalloy microstructures using time-resolved x-ray photoemission electron microscope 2004 Journal Of Applied Physics
    Vol. 95(11), pp. 6530-6532 
    article DOI  
    Abstract: We present results of a direct imaging approach to visualize the dynamics of magnetic domains on the nanosecond scale. The experiments are carried out by means of an x-ray photoemission electron microscope (X-PEEM) in a stroboscopic mode and exploit the intrinsic time structure of the synchrotron radiation delivered by the storage ring facility ESRF (Grenoble). In this way we combine the high lateral resolution of a PEEM with a subnanosecond time resolution. (C) 2004 American Institute of Physics.
    BibTeX:
    @article{Kuksov2004,
      author = {Kuksov, A. and Schneider, C. M. and Oelsner, A. and Krasyuk, A. and Neeb, D. and Schönhense, G. and De Nadai, C. and Brookes, N. B.},
      title = {Investigating magnetization dynamics in permalloy microstructures using time-resolved x-ray photoemission electron microscope},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {2004},
      volume = {95},
      number = {11},
      pages = {6530--6532},
      doi = {http://dx.doi.org/10.1063/1.1687531}
    }
    
    Nepijko, S.A., Oelsner, A., Krasyuk, A., Gloskovskii, A., Sedov, N.N., Schneider, C.M. & Schönhense, G. Lateral resolving power of a time-of-flight photoemission electron microscope 2004 Applied Physics A-Materials Science & Processing
    Vol. 78(1), pp. 47-51 
    article DOI  
    Abstract: The lateral resolution of a time-of-flight photoemission electron microscope has been theoretically analyzed. It has been shown that the resolution limit can reach a few nanometers. The lateral resolution will be higher if the photoelectrons forming the image are characterized by a smaller acceptance angle obtained with the help of diaphragms in the crossover plane, a higher initial energy and a narrower interval of electron energies. The experimental results are in good agreement with the theoretical predictions.
    BibTeX:
    @article{Nepijko2004,
      author = {Nepijko, S. A. and Oelsner, A. and Krasyuk, A. and Gloskovskii, A. and Sedov, N. N. and Schneider, C. M. and Schönhense, G.},
      title = {Lateral resolving power of a time-of-flight photoemission electron microscope},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer-Verlag},
      year = {2004},
      volume = {78},
      number = {1},
      pages = {47--51},
      doi = {http://dx.doi.org/10.1007/s00339-003-2291-5}
    }
    
    Oelsner, A., Krasyuk, A., Fecher, G.H., Schneider, C.M. & Schönhense, G. Image enhancement in photoemission electron microscopy by means of imaging time-of-flight analysis 2004 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 137-40, pp. 757-761 
    article DOI  
    Abstract: Photoemission electron microscopy (PEEM) is widely used in combination with synchrotron sources as a powerful tool to observe chemical and magnetic properties of metal and semiconductor surfaces. Presently, the resolution limit of these instruments using soft-X-ray excitation is limited to about 50 nm, because of the chromatic aberation of the electron optics used. Various sophisticated approaches have thus been reported for enhancing the spatial resolution in photoemission electron microscopy. This work demonstrates the use of a simple imaging energy filter based on electron time-of-flight (ToF) selection. The spatial resolution could be improved dramatically, even though the instrument was optimized using a rather large contrast aperture of 50 mum. A special (x, y, t)-resolving delayline detector was used as the imaging unit of this ToF-PEEM. It is operated in phase with the time structure of the synchrotron source, cutting time intervals from the raw image-forming data set in order to reduce the electron energy width contributing to the final images. (C) 2004 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Oelsner2004,
      author = {Oelsner, A. and Krasyuk, A. and Fecher, G. H. and Schneider, C. M. and Schönhense, G.},
      title = {Image enhancement in photoemission electron microscopy by means of imaging time-of-flight analysis},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {137-40},
      pages = {757--761},
      doi = {http://dx.doi.org/10.1016/j.elspec.2004.02.163}
    }
    
    Oelsner, A., Krasyuk, A., Neeb, D., Nepijko, S.A., Kuksov, A., Schneider, C.M. & Schönhense, G. Magnetization changes visualized using photoemission electron microscopy 2004 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 137-40, pp. 751-756 
    article DOI  
    Abstract: Photoemission electron microscopy was used to visualize the motion of magnetic domains on a sub-nanosecond timescale. The technique exploits the imaging of magnetic domains using soft X-ray circular dichroism, with the special feature that the instrument utilizes a fast image acquisition system with intrinsic 125 ps time resolution. The overall time resolution used is about 500 ps. Different domains and domain movements have been observed in lithographically-produced Permalloy structures on a copper microstrip-line. A current pulse of I = 0.5 A with rise times of about 300 ps switched the Permalloy islands from a Landau-Lifshitz type domain configuration into metastable s-state domain configurations. A pulse with opposite direction could reverse these s-type patterns. Photoemission electron microscopy was employed to observe the domain movements while repeating current pulses passed the microstrip-line. Using small unipolar amplitudes, only the cross-tie walls of the s-type patterns disappear and the pattern becomes "fuzzy", e.g. the domain rims are not sharp and some domains change their size. Before the structure switches at a current threshold, it is more fluctuating as shown by significant differences in sharpness of the islands rim and the inter-domain boundaries show. The device behavior complicates when a bi-polar pulse is applied. Switching and oscillating of domains is observed in various manners, e.g. very tiny domains appear and unify again. (C) 2004 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Oelsner2004a,
      author = {Oelsner, A. and Krasyuk, A. and Neeb, D. and Nepijko, S. A. and Kuksov, A. and Schneider, C. M. and Schönhense, G.},
      title = {Magnetization changes visualized using photoemission electron microscopy},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {137-40},
      pages = {751--756},
      doi = {http://dx.doi.org/10.1016/j.elspec.2004.02.089}
    }
    
    Prokop, J., Valdaitsev, D.A., Kukunin, A., Pratzer, M., Schönhense, G. & Elmers, H.J. Strain-induced magnetic anisotropies in Co films on Mo(110) 2004 Physical Review B
    Vol. 70(18), pp. 184423 
    article DOI  
    Abstract: Mo/Co(0001)/Mo(110) epitaxial films were grown by molecular beam epitaxy in ultrahigh vacuum on (11 (2) over bar0) oriented alpha-Al2O3 substrates. Co grows on Mo(110) in the Nishiyama-Wassermann orientation, i.e., [1 (1) over bar 00]Coparallel to[1 (1) over bar0]Mo. Low energy electron diffraction reveals a lateral expansive strain of the Co film independent of the thickness. Magnetic anisotropies were obtained from hard-axis magnetization loops measured by Kerr magnetometry in longitudinal and polar geometry. Magnetic interface anisotropies are very small (<0.04 mJ/m(2)). Deviations of the volume-type in-plane (K-v,K-p=0.79 MJ/m(3)) and out-of-plane (K-v=-9.5 MJ/m(3)) anisotropies from bulk values for hexagonal-close-packed Co are attributed to magnetoelastic anisotropies.
    BibTeX:
    @article{Prokop2004,
      author = {Prokop, J. and Valdaitsev, D. A. and Kukunin, A. and Pratzer, M. and Schönhense, G. and Elmers, H. J.},
      title = {Strain-induced magnetic anisotropies in Co films on Mo(110)},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2004},
      volume = {70},
      number = {18},
      pages = {184423},
      doi = {http://dx.doi.org/10.1103/PhysRevB.70.184423}
    }
    
    von Przychowski, M.D., Marx, G.K.L., Fecher, G.H. & Schönhense, G. A spatially resolved investigation of oxygen adsorption on polycrystalline copper and titanium by means of photoemission electron microscopy 2004 Surface Science
    Vol. 549(1), pp. 37-51 
    article DOI  
    Abstract: The interaction of oxygen with polycrystalline copper and titanium surfaces was studied by means of photoemission electron microscopy. Variations in the image brightness were used to determine the work function of different Cu crystallites. The change of the work function was monitored during oxygen adsorption on both, Cu and Ti. Those changes are smooth for Cu whereas different Ti crystallites exhibit a rather complicated behavior during oxygen adsorption. The transformation of brightness versus exposure curves into work function versus coverage curves allows to determine the initial dipole moment of the adsorbed oxygen atoms. A value of about 20 mD was found for O on Cu(110). Variations of the initial sticking probability of oxygen on different copper crystallites were directly mapped. (C) 2003 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Przychowski2004,
      author = {von Przychowski, M. D. and Marx, G. K. L. and Fecher, G. H. and Schönhense, G.},
      title = {A spatially resolved investigation of oxygen adsorption on polycrystalline copper and titanium by means of photoemission electron microscopy},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {549},
      number = {1},
      pages = {37--51},
      doi = {http://dx.doi.org/10.1016/j.susc.2003.09.049}
    }
    
    Schneider, C.M., Kuksov, A., Krasyuk, A., Oelsner, A., Neeb, D., Nepijko, S.A., Schönhense, G., Monch, I., Kaltofen, R., Morais, J., de Nadai, C. & Brookes, N.B. Incoherent magnetization rotation observed in subnanosecond time-resolving x-ray photoemission electron microscopy 2004 Applied Physics Letters
    Vol. 85(13), pp. 2562-2564 
    article DOI  
    Abstract: We present recent results of time-resolved x-ray photoemission electron microscopy on permalloy microstructures. The stroboscopic experiments feature a time-resolution of Deltatauless than or equal to130 ps. We observe a strong influence of incoherent magnetization rotation processes, leading to a significant transient stray-field formation at the edges of the microstructure. (C) American Institute of Physics.
    BibTeX:
    @article{Schneider2004,
      author = {Schneider, C. M. and Kuksov, A. and Krasyuk, A. and Oelsner, A. and Neeb, D. and Nepijko, S. A. and Schönhense, G. and Monch, I. and Kaltofen, R. and Morais, J. and de Nadai, C. and Brookes, N. B.},
      title = {Incoherent magnetization rotation observed in subnanosecond time-resolving x-ray photoemission electron microscopy},
      journal = {Applied Physics Letters},
      publisher = {Amer Inst Physics},
      year = {2004},
      volume = {85},
      number = {13},
      pages = {2562--2564},
      doi = {http://dx.doi.org/10.1063/1.1790606}
    }
    
    Schönhense, G. Surface magnetism studied by photoelectron spectromicroscopy with high spatial and time resolution 2004 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 137-40, pp. 769-783 
    article DOI  
    Abstract: Photoemission electron microscopy (PEEM) is widely used for the study of magnetic surfaces and thin films. Ferromagnetic and antiferromagnetic microstructures are investigated exploiting magnetic circular and linear dichroism in the soft X-ray range using tuneable synchrotron radiation. Local dichroism spectroscopy gives access to magnetic moments of the elements in compounds or multilayer materials. Beyond these achievements, the method bears a high future potential with respect to an increased lateral resolution via aberration correction of the electron optics and a high time resolution in the 100 ps range for the study of dynamic processes. In addition, photoelectron spin polarisation analysis implemented into PEEM provides a novel local probe for the investigation of spin dynamics. The current instrumental state-of-the-art and the future potential of PEEM in the field of surface and thin-film magnetism are discussed and illustrated by recent examples. (C) 2004 Published by Elsevier B.V.
    BibTeX:
    @article{Schoenhense2004,
      author = {Schönhense, G.},
      title = {Surface magnetism studied by photoelectron spectromicroscopy with high spatial and time resolution},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2004},
      volume = {137-40},
      pages = {769--783},
      doi = {http://dx.doi.org/10.1016/j.elspec.2004.02.161}
    }
    
    Wurmehl, S., Fecher, G.H., Kandpal, H.C., Kroth, K., Elmers, H.-J., Schönhense, G., Felser, C., Morais, J., Hwu, Y. & Klauser, R. Charakterisierung von dotierten Heusler-Verbindungen: Co2Cr1-xFexAl 2004 Z. Anorg. Allg. Chem.
    Vol. 630 , pp. 1771 
    article URL 
    BibTeX:
    @article{Wurmehl2004,
      author = {Wurmehl, S. and Fecher, G. H. and Kandpal, H. C. and Kroth, K. and Elmers, H.-J. and Schönhense, G. and Felser, C. and Morais, J. and Hwu, Y. and Klauser, R.},
      title = {Charakterisierung von dotierten Heusler-Verbindungen: Co2Cr1-xFexAl},
      journal = {Z. Anorg. Allg. Chem.},
      year = {2004},
      volume = {630 },
      pages = {1771},
      url = {http://www3.interscience.wiley.com/cgi-bin/abstract/109607008/ABSTRACT}
    }
    
    Cinchetti, M., Oelsner, A., Fecher, G.H., Elmers, H.J. & Schönhense, G. Observation of Cu surface inhomogeneities by multiphoton photoemission spectromicroscopy 2003 Applied Physics Letters
    Vol. 83(8), pp. 1503-1505 
    article DOI  
    Abstract: The spatially resolved energy distribution of electrons emitted from a polycrystalline copper surface has been studied by multiphoton photoemission. Electron emission was induced by femtosecond laser excitation and detected by an emission electron microscope combined with a time-of-flight detector to allow spatially resolved energy analysis. The energy distributions obtained from small spots with strongly enhanced electron emission yield (so-called hot spots) turned out to be different from those measured for homogeneous surface regions. The latter directly reflect two photon photoemission spectra from Cu as was previously observed in spatially averaging experiments. The hot spots, however, are characterized by a slightly lower work function and a strongly enhanced intensity if excited by s-polarized light. The peak positions of these spectra do not depend on the photon energy as is characteristic for a true secondary process. This indicates a different electron emission mechanism in the hot spots compared to homogeneous surfaces. (C) 2003 American Institute of Physics.
    BibTeX:
    @article{Cinchetti2003,
      author = {Cinchetti, M. and Oelsner, A. and Fecher, G. H. and Elmers, H. J. and Schönhense, G.},
      title = {Observation of Cu surface inhomogeneities by multiphoton photoemission spectromicroscopy},
      journal = {Applied Physics Letters},
      publisher = {Amer Inst Physics},
      year = {2003},
      volume = {83},
      number = {8},
      pages = {1503--1505},
      doi = {http://dx.doi.org/10.1063/1.1603332}
    }
    
    Elmers, H.J., Fecher, G.H., Valdaitsev, D., Nepijko, S.A., Gloskovskii, A., Jakob, G., Schönhense, G., Wurmehl, S., Block, T., Felser, C., Hsu, P.C., Tsai, W.L. & Cramm, S. Element-specific magnetic moments from core-absorption magnetic circular dichroism of the doped Heusler alloy Co2Cr0.6Fe0.4Al 2003 Physical Review B
    Vol. 67(10), pp. 104412 
    article DOI  
    Abstract: The magnetic circular dichroism (MCD) of core-level absorption (x-ray absorption spectroscopy, XAS) spectra in the soft x-ray region has been measured for the ferromagnetic Heusler alloy Co2Cr0.6Fe0.4Al at the Co, Fe, and Cr L-II,L-III edges. The comparison of XAS spectra before and after in situ cleaning of polished surfaces revealed a pronounced selective oxidation of Cr in air. For clean surfaces we observed a MCD for all three elements with Fe showing the largest moment per atom. The MCD can be explained by the density of states of the 3d unoccupied states, predicted by linear muffin-tin orbital atomic sphere approximation. For Fe and Cr the orbital angular momentum component of the magnetic moment is considerably larger than the values reported for metallic alloys, whereas for Co a value close to its bulk value is observed. This observation is discussed in comparison with band structure calculations.
    BibTeX:
    @article{Elmers2003,
      author = {Elmers, H. J. and Fecher, G. H. and Valdaitsev, D. and Nepijko, S. A. and Gloskovskii, A. and Jakob, G. and Schönhense, G. and Wurmehl, S. and Block, T. and Felser, C. and Hsu, P. C. and Tsai, W. L. and Cramm, S.},
      title = {Element-specific magnetic moments from core-absorption magnetic circular dichroism of the doped Heusler alloy Co2Cr0.6Fe0.4Al},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {2003},
      volume = {67},
      number = {10},
      pages = {104412},
      doi = {http://dx.doi.org/10.1103/PhysRevB.67.104412}
    }
    
    Felser, C., Heitkamp, B., Kronast, F., Schmitz, D., Cramm, S., Durr, H.A., Elmers, H.J., Fecher, G.H., Wurmehl, S., Block, T., Valdaitsev, D., Nepijko, S.A., Gloskovskii, A., Jakob, G., Schönhense, G. & Eberhardt, W. Investigation of a novel material for magnetoelectronics: Co2Cr0.6Fe0.4Al 2003 Journal Of Physics-Condensed Matter
    Vol. 15(41), pp. 7019-7027 
    article DOI  
    Abstract: Heusler compounds are promising candidates for future spintronics device applications. The electronic and magnetic properties Of Co2Cr0.6Fe0.4Al, an electron-doped derivative Of Co2CrAl, are investigated using circularly polarized synchrotron radiation and photoemission electron microscopy (PEEM). Element specific imaging reveals needle shaped Cr rich phases in a homogeneous bulk of the Heusler compound. The ferromagnetic domain structure is investigated on an element-resolved basis using x-ray magnetic circular dichroism (XMCD) contrast in PEEM. The structure is characterized by micrometre-size domains with a superimposed fine ripple structure; the lateral resolution in these images is about 100 nm. The domains look identical for Co and Fe giving evidence of a ferromagnetic coupling of these elements. No ferromagnetic contrast is observed at the Cr line. Magnetic spectroscopy exploiting XMCD reveals that the lack of magnetic moment, detected in a SQUID magnetometer, is mainly due to the moment of the Cr atom.
    BibTeX:
    @article{Felser2003,
      author = {Felser, C. and Heitkamp, B. and Kronast, F. and Schmitz, D. and Cramm, S. and Durr, H. A. and Elmers, H. J. and Fecher, G. H. and Wurmehl, S. and Block, T. and Valdaitsev, D. and Nepijko, S. A. and Gloskovskii, A. and Jakob, G. and Schönhense, G. and Eberhardt, W.},
      title = {Investigation of a novel material for magnetoelectronics: Co2Cr0.6Fe0.4Al},
      journal = {Journal Of Physics-Condensed Matter},
      publisher = {Iop Publishing Ltd},
      year = {2003},
      volume = {15},
      number = {41},
      pages = {7019--7027},
      doi = {http://dx.doi.org/10.1088/0953-8984/15/41/010}
    }
    
    Krasyuk, A., Oelsner, A., Nepijko, S.A., Kuksov, A., Schneider, C.M. & Schönhense, G. Time-resolved photoemission electron microscopy of magnetic field and magnetisation changes 2003 Applied Physics A-Materials Science & Processing
    Vol. 76(6), pp. 863-868 
    article DOI  
    Abstract: Owing to its parallel image acquisition, photoemission electron microscopy is well suited for real-time observation of fast processes on surfaces. Pulsed excitation sources like synchrotron radiation or lasers, fast electric pulsers for the study of magnetic switching, and/or time-resolved detection can be utilised. A standard approach also being used in light optical imaging is stroboscopic illumination of a periodic (or quasi-periodic) process. Using this technique, the time dependence of the magnetic field in a pulsed microstrip line has been imaged in real time exploiting Lorentz-type contrast. Similarly, the corresponding field-induced changes in the magnetisation of cobalt microstructures deposited on the microstrip line have been observed exploiting magnetic X-ray circular dichroism as a contrast mechanism. The experiment has been performed at the UE 56/1-PGM at BESSY II (Berlin) in the single-bunch mode.
    BibTeX:
    @article{Krasyuk2003,
      author = {Krasyuk, A. and Oelsner, A. and Nepijko, S. A. and Kuksov, A. and Schneider, C. M. and Schönhense, G.},
      title = {Time-resolved photoemission electron microscopy of magnetic field and magnetisation changes},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer-Verlag},
      year = {2003},
      volume = {76},
      number = {6},
      pages = {863--868},
      doi = {http://dx.doi.org/10.1007/s00339-002-1965-8}
    }
    
    Nepijko, S.A., Klais, M., Schönhense, G., Cramer, N., Celinski, Z., Schneider, C.M., Zennaro, S., Zema, N. & Sedov, N.N. Micromagnetism of two-dimensional permalloy particles with different aspect ratios 2003 Applied Physics A-Materials Science & Processing
    Vol. 76(5), pp. 809-815 
    article DOI  
    Abstract: Micromagnetic properties of the Fe19Ni81 (5 nm)/ NiO (50 nm)/Fe19Ni81 (30 nm) structured system have been investigated in a photoemission electron microscope in the magnetic X-ray circular dichroism operating mode. The microstructured Fe19Ni81 (5 nm) film contained two-dimensional islands with the aspect ratio varying from 1 : 1 to 10 : 1, and the linear size of their long axis comprised 24, 12 and 6 mum. It is shown that the magnetic domains have the direction of magnetization preferentially parallel and antiparallel to the magnetic field direction in which this system was prepared. Their number is determined by the particles' sizes, their shape as well as by the direction of the external magnetizing field and can be characterized by a non-monotonic size dependence. The magnetization of domains with different lateral sizes was found to be 0.4 T with an accuracy better than 20%.
    BibTeX:
    @article{Nepijko2003,
      author = {Nepijko, S. A. and Klais, M. and Schönhense, G. and Cramer, N. and Celinski, Z. and Schneider, C. M. and Zennaro, S. and Zema, N. and Sedov, N. N.},
      title = {Micromagnetism of two-dimensional permalloy particles with different aspect ratios},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer},
      year = {2003},
      volume = {76},
      number = {5},
      pages = {809--815},
      doi = {http://dx.doi.org/10.1007/s00339-002-1827-4}
    }
    
    Nepijko, S.A., Gloskovskii, A., Sedov, N.N. & Schönhense, G. Measurement of the electric field distribution and potentials on the object surface in an emission electron microscope without restriction of the electron beams 2003 Journal Of Microscopy
    Vol. 211, pp. 89-94 
    article DOI  
    Abstract: An emission electron microscope without restriction of the electron beams was used to visualize and measure the distribution of electric fields and potentials on the surface under study. Investigations of this kind can be performed in an emission electron microscope without any aperture diaphragm. The potentialities of this method have been demonstrated using measurements with a silicon p-n junction to which a voltage has been applied in the reverse direction. The quantitative analysis becomes more complicated if the specimen is characterized by a heterogeneous intensity distribution of the electron emission from different areas of its surface. In the latter case two images obtained at different accelerating voltages (i.e. different voltages of the microscope extractor) provide the information necessary for an analysis of electric field and potential distributions.
    BibTeX:
    @article{Nepijko2003a,
      author = {Nepijko, S. A. and Gloskovskii, A. and Sedov, N. N. and Schönhense, G.},
      title = {Measurement of the electric field distribution and potentials on the object surface in an emission electron microscope without restriction of the electron beams},
      journal = {Journal Of Microscopy},
      publisher = {Blackwell Publishing Ltd},
      year = {2003},
      volume = {211},
      pages = {89--94},
      doi = {http://dx.doi.org/10.1046/j.1365-2818.2003.01199.x}
    }
    
    von Przychowski, M.D., Wiechert, H., Marx, G.K.L. & Schönhense, G. Real-space observation of xenon adsorption and desorption kinetics on graphite (0001) by photoemission electron microscopy 2003 Surface Science
    Vol. 541(1-3), pp. 46-58 
    article DOI  
    Abstract: The growth and desorption of Xe monolayers on the basal plane of graphite has been investigated by real-space imaging using photoemission electron microscopy. Adsorption kinetics was studied at different substrate temperatures (39-65 K), corresponding to different growth modes. Coexisting phases showed up as different grey values in the image. Typical domain sizes of the 2D solid phases around 60 K are of the order of one to several mum. The domains exhibit an elongated shape with their long axis oriented preferentially parallel to step edges of the substrate. With increasing coverage the brightness of the domains increases, the 2D gas-phase regions shrink and finally disappear at high coverage, in agreement with the phase diagram of Xe films. The saturated monolayer at 60 K shows a "wave-like" structure indicating coexistence of the commensurate (root3 x root3)R30degrees and an incommensurate 2D solid phase. Desorption kinetics has been studied at temperatures between 70 and 75 K. The close-packed monolayer breaks up into many small islands, again oval-shaped and oriented along the step edges, which in turn loose intensity, shrink and finally disappear at 74.4 K. The line scans and histograms of the grey values reveal that during desorption the islands of the commensurate phase persist down to low coverages and the incommensurate and 2D gas phase decrease in 2D Xe density. (C) 2003 Elsevier B.V. All rights reserved.
    BibTeX:
    @article{Przychowski2003,
      author = {von Przychowski, M. D. and Wiechert, H. and Marx, G. K. L. and Schönhense, G.},
      title = {Real-space observation of xenon adsorption and desorption kinetics on graphite (0001) by photoemission electron microscopy},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {2003},
      volume = {541},
      number = {1-3},
      pages = {46--58},
      doi = {http://dx.doi.org/10.1016/S0039-6028(03)00820-3}
    }
    
    Fecher, G.H., Kuznetsov, V.V., Cherepkov, N.A. & Schönhense, G. Influence of the symmetry on the circular dichroism in angular resolved core-level photoemission 2002 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 122(2), pp. 157-180 
    article DOI  
    Abstract: The model for angular resolved photoemission from adsorbed atoms is extended to account for the non-axial symmetry of atoms in a crystal field. In particular, circular dichroism in the angular distribution (CDAD) is theoretically investigated. A special emphasis is put on the case when incident photons are propagating along the principal axis of an atom in C-np symmetry. The model, although mainly developed for adsorbates, may also be used as a base for emission from solid surfaces. An extension to simple bulk symmetries, like D-6h for hexagonal or O-h for cubic crystals, is included. The CDAD for normal incidence does not vanish in the extended model and reflects the symmetry of the adsorption site. Scattering induced final state effects are discussed for alkali metal adsorption. A numerical calculation of the emission from the shallow 4p core level of Rb atoms adsorbed in a (root3 x root3)-R30degrees structure on a Pt(111) surface is presented. In this case even the extended photoemission model predicts the absence of CDAD. The appearance of CDAD is only possible due to the scattering of photoelectrons from the neighbouring atoms of the solid. (C) 2002 Published by Elsevier Science B.V.
    BibTeX:
    @article{Fecher2002,
      author = {Fecher, G. H. and Kuznetsov, V. V. and Cherepkov, N. A. and Schönhense, G.},
      title = {Influence of the symmetry on the circular dichroism in angular resolved core-level photoemission},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2002},
      volume = {122},
      number = {2},
      pages = {157--180},
      doi = {http://dx.doi.org/10.1016/S0368-2048(01)00355-3}
    }
    
    Fecher, G.H., Schmidt, O., Hwu, Y. & Schönhense, G. Multiphoton photoemission electron microscopy using femtosecond laser radiation 2002 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 126(1-3), pp. 77-87 
    article DOI  
    Abstract: The interaction of intense, pulsed laser radiation with surfaces results in non-linear optical effects that are responsible for emission of electrons even if the photon energies are below the work function. In the present study, photoelectrons have been excited by means of femtosecond laser pulses from a frequency doubled Ti:sapphire laser with a photon energy of 3.1 W The spatial distribution of the photo emitted electrons was imaged using a photoemission electron microscope. All samples exhibit centres of enhanced second or higher order photoemission yield, so called 'hot spots'. These 'hot spots' were preferentially excited with s-polarised light. This behaviour may be explained on the basis of a microscopic model assuming localised plasmon excitations in small particles. Lead films and pentacene layers adsorbed on silicon have been studied. The photoelectron yield depends strongly on the sample topography and the polarisation of the photons. The polarisation and power dependence of the multi-photon photoemission yield were studied. Clear evidence for three-photon contributions has been found although two-photon photoemission is sufficient to overcome the surface barrier. (C) 2002 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Fecher2002a,
      author = {Fecher, G. H. and Schmidt, O. and Hwu, Y. and Schönhense, G.},
      title = {Multiphoton photoemission electron microscopy using femtosecond laser radiation},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2002},
      volume = {126},
      number = {1-3},
      pages = {77--87},
      doi = {http://dx.doi.org/10.1016/S0368-2048(02)00143-3}
    }
    
    Fecher, G.H., Braun, J., Oelsner, A., Ostertag, C. & Schönhense, G. Dichroism in angle-resolved photoemission from Pt(111) 2002 Surface Review And Letters
    Vol. 9(2), pp. 883-888 
    article DOI  
    Abstract: The angular dependence of the circular dichroism in photoemission from Pt(111) was investigated for excitation with VUV and soft X-ray radiation. VUV excitation was used to probe band structure and the circular dichroism for valence band emission. The measurements are compared to full relativistic single step photoemission calculations. XPS was used to investigate the circular dichroism in emission from the 4f core level. In this case, the dichroism is induced by photoelectron diffraction. First results from single step core level calculations are compared to the experimental observations.
    BibTeX:
    @article{Fecher2002b,
      author = {Fecher, G. H. and Braun, J. and Oelsner, A. and Ostertag, C. and Schönhense, G.},
      title = {Dichroism in angle-resolved photoemission from Pt(111)},
      journal = {Surface Review And Letters},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2002},
      volume = {9},
      number = {2},
      pages = {883--888},
      doi = {http://dx.doi.org/10.1142/S0218625X0200310X}
    }
    
    Fecher, G., Kuznetsov, V., Cherepkov, N.A. & Schönhense, G. Extension of the Atomic Model for Consideration of Photoemission From Solids and Adsorbed Atoms 2002 J. Electron Spectr. Relat. Phenom.
    Vol. 122, pp. 157-180 
    article  
    BibTeX:
    @article{Fecher2002c,
      author = {Fecher, G. and Kuznetsov, V.V. and Cherepkov, N. A. and Schönhense, G.},
      title = {Extension of the Atomic Model for Consideration of Photoemission From Solids and Adsorbed Atoms},
      journal = {J. Electron Spectr. Relat. Phenom.},
      year = {2002},
      volume = {122},
      pages = {157-180}
    }
    
    Kuznetsov, V.V., Cherepkov, N.A., Fecher, G.H. & Schönhense, G. Angular distributions and dichroism of photoelectrons ejected from fixed-in-space molecules of definite symmetry: Application to the C-2v symmetry group 2002 Journal Of Chemical Physics
    Vol. 117(15), pp. 7180-7197 
    article DOI  
    Abstract: A theoretical investigation of the angular distributions of photoelectrons (ADP) ejected from fixed-in-space molecules or clusters having C-2v symmetry is presented. The consideration is based on an expansion of the photoelectron wave functions in symmetry-adapted spherical harmonics. The ADP is derived for linearly polarized, circularly polarized, and unpolarized light in the case when the light beam is parallel to the C-2 axis of the molecule. The twofold symmetry of the target reveals itself most clearly for circularly polarized or unpolarized light if the dependence on the azimuthal angle is studied for a fixed polar angle. The circular dichroism in the angular distribution (CDAD) is investigated for the general case of an arbitrary direction of the photon beam. It is shown on model examples that the CDAD has characteristic zeros in the mirror planes of the molecule that may be used to determine the symmetry of the initial state. For linearly polarized light the photoelectron angular distributions have a more complicated dependence on the azimuthal angle, though it also may be used to distinguish between different initial states. The examples presented in this paper demonstrate the general properties of the angular distributions as well as properties of the circular and linear dichroism in the angular distribution. (C) 2002 American Institute of Physics.
    BibTeX:
    @article{Kuznetsov2002,
      author = {Kuznetsov, V. V. and Cherepkov, N. A. and Fecher, G. H. and Schönhense, G.},
      title = {Angular distributions and dichroism of photoelectrons ejected from fixed-in-space molecules of definite symmetry: Application to the C-2v symmetry group},
      journal = {Journal Of Chemical Physics},
      publisher = {Amer Inst Physics},
      year = {2002},
      volume = {117},
      number = {15},
      pages = {7180--7197},
      doi = {http://dx.doi.org/10.1063/1.1507586}
    }
    
    Nepijko, S.A., Sedov, N.N., Schönhense, G. & Escher, M. Use of emission electron microscope for potential mapping in semiconductor microelectronics 2002 Journal Of Microscopy
    Vol. 206, pp. 132-138 
    article DOI  
    Abstract: An emission electron microscope was used for visualization and measurement of the distribution of electric fields and potentials on the surface under study. The contrast of microfields is caused by the fact that slow-moving electrons emitted from the object surface are deflected by these fields. The measurements were performed on a p-n junction to which a voltage was applied. It is shown that the type of contrast from the p-n junction can be reversed depending on the position of the contrast aperture restricting the electron beam. The same result was obtained by means of a computer simulation.
    BibTeX:
    @article{Nepijko2002,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G. and Escher, M.},
      title = {Use of emission electron microscope for potential mapping in semiconductor microelectronics},
      journal = {Journal Of Microscopy},
      publisher = {Blackwell Publishing Ltd},
      year = {2002},
      volume = {206},
      pages = {132--138},
      doi = {http://dx.doi.org/10.1046/j.1365-2818.2002.01012.x}
    }
    
    Nepijko, S.A., Sedov, N.N., Schönhense, G., Muschiol, U., Schneider, C.M., Zennaro, S. & Zema, N. Resolution of an emission electron microscope in the presence of magnetic fields on the object 2002 Annalen der Physik
    Vol. 11(6), pp. 461-471 
    article DOI  
    Abstract: The known Bruche-Recknagel formula for determining the resolving power of an emission electron microscope (EEM) was derived assuming idealized conditions: the object surface was planar, and the accelerating electric field was homogeneous. However, deviations from these conditions will deteriorate the resolving power. This can be caused by a surface topography as well as local electric or magnetic fields on the object surface. In the present paper the resolving power of an EEM is calculated for the case when there are local magnetic fields on the object surface. The deterioration of the resolving power will then depend on the local field strength not only in the given point of the object surface, but also in adjacent regions. The estimations performed show that the lateral resolution in EEM under the influence of magnetic microfields of real ferromagnets can be several times worse than in the case of the absence of these fields.
    BibTeX:
    @article{Nepijko2002a,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G. and Muschiol, U. and Schneider, C. M. and Zennaro, S. and Zema, N.},
      title = {Resolution of an emission electron microscope in the presence of magnetic fields on the object},
      journal = {Annalen der Physik},
      publisher = {Wiley-V C H Verlag Gmbh},
      year = {2002},
      volume = {11},
      number = {6},
      pages = {461--471},
      doi = {http://dx.doi.org/10.1002/1521-3889(200206)11:6<461::AID-ANDP461>3.0.CO;2-6}
    }
    
    Nepijko, S.A., Sedov, N.N., Schmidt, O., Fecher, G.H. & Schönhense, G. Size of three-dimensional objects measured by means of photoemission electron microscopy 2002 Annalen Der Physik
    Vol. 11(1), pp. 39-47 
    article DOI  
    Abstract: Pb particles on a Si(I I I) substrate were investigated using a photoemission electron microscope (PEEM). The electrons have been excited by a linearly polarised femtosecond laser beam with a wavelength of lambda = 400 run. The PEEM images exhibit an unusually high contrast. They arise due to photoemission being of a nontrivial nature because the photon energy is lower than the work function of the sample. It may be caused by the following processes: two- or multi-photon absorption, tunnel-photoeffect induced by a strong lowering of the potential barrier owing to enhancement of the electrical field of the powerful incident light wave on a rough surface, generation of second harmonic with its following absorption, or electron gas heating. Images obtained with orthogonal directions of the photon polarisation were compared to estimate the shape of different Pb particles. The size of the islands was determined by two methods, either from the shape of the spatial brightness distribution or from the area under the curve of this distribution.
    BibTeX:
    @article{Nepijko2002b,
      author = {Nepijko, S. A. and Sedov, N. N. and Schmidt, O. and Fecher, G. H. and Schönhense, G.},
      title = {Size of three-dimensional objects measured by means of photoemission electron microscopy},
      journal = {Annalen Der Physik},
      publisher = {Wiley-V C H Verlag Gmbh},
      year = {2002},
      volume = {11},
      number = {1},
      pages = {39--47},
      doi = {http://dx.doi.org/10.1002/1521-3889(200201)11:1<39::AID-ANDP39>3.0.CO;2-9}
    }
    
    Nepijko, S.A., Klais, M., Oelsner, A., Schmidt, O., Fecher, G.H., Schönhense, G., Muschiol, U., Schneider, C.M., Zennaro, S., Zema, N. & Sedov, N.N. New applications of the magnetic X-ray circular dichroism method for surface-magnetism investigations in a photoemission electron microscope 2002 Applied Physics A-Materials Science & Processing
    Vol. 74(2), pp. 295-298 
    article DOI  
    Abstract: It is shown that magnetic X-ray circular dichroism (MXCD) can be exploited in photoemission electron microscopy not only to visualize the domain structure of ferromagnets, but also to perform quantitative measurements of the stray magnetic fields at the domain boundaries. In the general situation, two MXCD images obtained at different extractor voltages are required. In specific cases, however, it suffices to consider a single image, if it is deformed by the stray magnetic fields compared to a known object geometry. The object geometry means its real shape, scratches or other defects. It is also possible to deposit a paramagnetic film structured in the form of stripes or a grid as a reference on the ferromagnetic sample being investigated.
    BibTeX:
    @article{Nepijko2002c,
      author = {Nepijko, S. A. and Klais, M. and Oelsner, A. and Schmidt, O. and Fecher, G. H. and Schönhense, G. and Muschiol, U. and Schneider, C. M. and Zennaro, S. and Zema, N. and Sedov, N. N.},
      title = {New applications of the magnetic X-ray circular dichroism method for surface-magnetism investigations in a photoemission electron microscope},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer-Verlag},
      year = {2002},
      volume = {74},
      number = {2},
      pages = {295--298},
      doi = {http://dx.doi.org/10.1007/s003390101027}
    }
    
    Oelsner, A., Ziethen, C., Fecher, G.H. & Schönhense, G. Imaging of dichroism in photoemission electron microscopy at nonmagnetic materials using circularly polarized soft X-rays 2002 Surface Review And Letters
    Vol. 9(1), pp. 509-513 
    article DOI  
    Abstract: A new approach for investigations of circular dichroism in the angular distribution of photoelectrons (CDAD) is presented. The image contrast using a photoemission line of a certain material is combined with imaging of the angular distribution pattern using a photoemission electron microscope (PEEM). CDAD can be used to investigate pure scattering information by means of the same instrument in microscopically selected regions on a surface. The experiment combines angle-resolved XPS imaging with the indirect mapping of the local environment of atoms by means of CDAD holography. In a conventional photoelectron diffraction or photoelectron holography experiment, it is necessary to move the sample and/or the detector; for example, a rotatable electron analyzer is used to map a full angular pattern. In the present approach, the diffraction plane is mapped for a certain kinetic energy of electrons in the backfocal plane. An imaging high-pass energy filter has been used in combination with the PEEM in order to acquire surface images and/or diffraction pattern maps. Direct photoemission from the W-4f core levels was observed at different photon polarization to obtain two images and two diffraction patterns of the W-4f emission line using light of opposite helicity. The agreement of calculations with the experimental result is satisfactory. This constitutes a very encouraging starting point for the use of the CDAD holography together with the PEEM technique providing mesoscopic and atomic as well as chemical resolution in microselected areas on solid surfaces.
    BibTeX:
    @article{Oelsner2002,
      author = {Oelsner, A. and Ziethen, C. and Fecher, G. H. and Schönhense, G.},
      title = {Imaging of dichroism in photoemission electron microscopy at nonmagnetic materials using circularly polarized soft X-rays},
      journal = {Surface Review And Letters},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2002},
      volume = {9},
      number = {1},
      pages = {509--513},
      doi = {http://dx.doi.org/10.1142/S0218625X02002555}
    }
    
    Oelsner, A., Schicketanz, M., Fecher, G.H., Schönhense, G. & Morais, J. An experimental proof of the back-scattering model for dichroic effects in VUV photoemission 2002 Surface Review And Letters
    Vol. 9(2), pp. 889-893 
    article DOI  
    Abstract: The energy dependence of the circular dichroism in the angular distribution of photoelectrons (CDAD) was investigated from the shallow Cs 5p core levels. Cesium was prepared in a hexagonal ordered monolayer on W(110). The results are mainly influenced by scattering of the photoelectrons within the adlayer. At low energies, the behavior observed is described by means of a model that treats only the back-scattering of photoelectrons at the potential step between the adlayer and the substrate. It leads to a simple method determining the position of the monolayer with respect to the substrate. In this approach, the back-scattering model is matched with the measured energy dependence of the CDAD between hv = 21 eV and hv = 33 eV. This procedure yields reliable results already for a single observation angle of the photoelectron. The distance between cesium and tungsten was determined to be (2.2 +/- 0.1) Angstrom, which corresponds to the effective distance between the center of the adsorbed layer and the potential step between the layer and the substrate. Finally, the fitted result was proven to meet the complete angular dependence of the CDAD at different photon energies.
    BibTeX:
    @article{Oelsner2002a,
      author = {Oelsner, A. and Schicketanz, M. and Fecher, G. H. and Schönhense, G. and Morais, J.},
      title = {An experimental proof of the back-scattering model for dichroic effects in VUV photoemission},
      journal = {Surface Review And Letters},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2002},
      volume = {9},
      number = {2},
      pages = {889--893},
      doi = {http://dx.doi.org/10.1142/S0218625X02003111}
    }
    
    Schicketanz, M., Oelsner, A., Fecher, G.H., Morais, J. & Schönhense, G. Magnetic coupling of alkali and rare-gas films adsorbed on a ferromagnetic surface 2002 Surface Review And Letters
    Vol. 9(2), pp. 895-899 
    article DOI  
    Abstract: The observation of magnetic circular dichroism in the angular distribution of photoelectrons (MCDAD) from alkali and rare-gas films adsorbed on a thin remanently magnetized Co layer is reported. The observation of an antisymmetric MCDAD near normal emission for Co(0001)-Cs 5p semi core level is shown. The reversed magnetization leads to a mirror-image-like distribution. The second system under investigation, physisorbed Co(0001)-Xe 5p, does not give such an but shows significant differences in the MCDAD signal for both directions of magnetization, in particular in the j) substates of the p(3/2) level. A magnetic coupling between Xe and Co is evident when we take results of spin-resolved photoemission into account.
    BibTeX:
    @article{Schicketanz2002,
      author = {Schicketanz, M. and Oelsner, A. and Fecher, G. H. and Morais, J. and Schönhense, G.},
      title = {Magnetic coupling of alkali and rare-gas films adsorbed on a ferromagnetic surface},
      journal = {Surface Review And Letters},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2002},
      volume = {9},
      number = {2},
      pages = {895--899},
      doi = {http://dx.doi.org/10.1142/S0218625X02003123}
    }
    
    Schmidt, O., Bauer, M., Wiemann, C., Porath, R., Scharte, M., Andreyev, O., Schönhense, G. & Aeschlimann, M. Time-resolved two photon photoemission electron microscopy 2002 Applied Physics B-Lasers And Optics
    Vol. 74(3), pp. 223-227 
    article DOI  
    Abstract: Femtosecond, time-resolved two photon photoemission has been used to map the dynamics of photo-excited electrons at a structured metal/semiconductor surface. A photoemission microscope was employed as a spatially resolving electron detector. This novel setup has the potential to visualize variations of hot electron lifetimes in the femtosecond regime on heterogeneous sample surfaces and nanostructures.
    BibTeX:
    @article{Schmidt2002,
      author = {Schmidt, O. and Bauer, M. and Wiemann, C. and Porath, R. and Scharte, M. and Andreyev, O. and Schönhense, G. and Aeschlimann, M.},
      title = {Time-resolved two photon photoemission electron microscopy},
      journal = {Applied Physics B-Lasers And Optics},
      publisher = {Springer-Verlag},
      year = {2002},
      volume = {74},
      number = {3},
      pages = {223--227},
      doi = {http://dx.doi.org/10.1007/s003400200803}
    }
    
    Schneider, C.M., de Haas, O., Tietjen, D., Muschiol, U., Cramer, N., Celinski, Z., Oelsner, A., Klais, M., Ziethen, C., Schmidt, O., Schönhense, G., Zema, N. & Zennaro, S. Size dependence of magnetic domain patterns in exchange-biased Permalloy/NiO microstructures 2002 Journal Of Physics D-Applied Physics
    Vol. 35(20), pp. 2472-2478 
    article DOI  
    Abstract: The magnetic domain structure in Permalloy (Ni81Fe19) micropatterns (10- 100 mum) on NiO has been investigated by means of soft x-ray photoemission electron microscopy. The exchange anisotropy between the Ni81Fe19 patterns and the NiO layer results in the formation of complex domain structures which markedly differ from the simple Landau-Lifshitz configurations. The domain structures reflect the competition between the exchange anisotropy and the dipole-dipole interaction in a weakly coupled system. The observed domain structures change with the feature size, as the domain patterns lose complexity in the smaller structures.
    BibTeX:
    @article{Schneider2002,
      author = {Schneider, C. M. and de Haas, O. and Tietjen, D. and Muschiol, U. and Cramer, N. and Celinski, Z. and Oelsner, A. and Klais, M. and Ziethen, C. and Schmidt, O. and Schönhense, G. and Zema, N. and Zennaro, S.},
      title = {Size dependence of magnetic domain patterns in exchange-biased Permalloy/NiO microstructures},
      journal = {Journal Of Physics D-Applied Physics},
      publisher = {Iop Publishing Ltd},
      year = {2002},
      volume = {35},
      number = {20},
      pages = {2472--2478},
      doi = {http://dx.doi.org/10.1088/0022-3727/35/20/302}
    }
    
    Schneider, C.M. & Schönhense, G. Investigating surface magnetism by means of photoexcitation electron emission microscopy 2002 Reports On Progress In Physics
    Vol. 65(12), pp. R1785-R1839 
    article DOI  
    Abstract: The imaging of surfaces by means of photoexcitation electron emission microscopy (PEEM) has recently received considerable interest. This is mainly due to the extended use and availability of brilliant synchrotron radiation in the soft x-ray regime which generally facilitates studies with surface specificity and chemical selectivity. The most popular application of the x-ray PEEM (XPEEM) technique concerns studies of magnetic systems and phenomena. By exploiting the high degree of circular or linear polarization of the synchrotron light, the magnetic microstructure in both ferromagnets and antiferromagnets can be visualized. In this contribution we demonstrate the unique potential and the versatility of the PEEM approach, and review the current status with a certain emphasis on experiments with soft x-ray excitation. In some cases, the high-energy excitation studies can be complemented by laboratory experiments employing threshold photoemission with ultraviolet light (UV-PEEM). Current limitations and future developments and perspectives of the PEEM technique applied to magnetic systems are discussed.
    BibTeX:
    @article{Schneider2002a,
      author = {Schneider, C. M. and Schönhense, G.},
      title = {Investigating surface magnetism by means of photoexcitation electron emission microscopy},
      journal = {Reports On Progress In Physics},
      publisher = {Iop Publishing Ltd},
      year = {2002},
      volume = {65},
      number = {12},
      pages = {R1785--R1839},
      doi = {http://dx.doi.org/10.1088/0034-4885/65/12/202}
    }
    
    Schönhense, G. & Spiecker, H. Correction of chromatic and spherical aberration in electron microscopy utilizing the time structure of pulsed excitation sources 2002 Journal Of Vacuum Science & Technology B
    Vol. 20(6), pp. 2526-2534 
    article DOI  
    Abstract: A theoretical ansatz for correction of the chromatic and spherical aberration of round-lens systems in photoemission and low-energy electron microscopy (PEEM/LEEM) is presented. The method is based on fast switching of electrical acceleration or lens fields. It exploits the highly precise time structure of pulsed photon sources like electron storage rings for synchrotron radiation or pulsed lasers as well as pulsed photocathodes of a LEEM. The initial results indicate that the approach is a promising alternative to the implementation of multipole or mirror correctors in the electron optical column of a microscope. (C) 2002 American Vacuum Society.
    BibTeX:
    @article{Schoenhense2002,
      author = {Schönhense, G. and Spiecker, H.},
      title = {Correction of chromatic and spherical aberration in electron microscopy utilizing the time structure of pulsed excitation sources},
      journal = {Journal Of Vacuum Science & Technology B},
      publisher = {A V S Amer Inst Physics},
      year = {2002},
      volume = {20},
      number = {6},
      pages = {2526--2534},
      doi = {http://dx.doi.org/10.1116/1.1523373}
    }
    
    Ziethen, C., Wegelin, F., Schönhense, G., Ohr, R., Neuhauser, M. & Hilgers, H. Soft X-ray photoelectron microscopy used for the characterization of diamond, a-C and CNx, thin films 2002 Diamond And Related Materials
    Vol. 11(3-6), pp. 1068-1073 
    article DOI  
    Abstract: This article gives an overview about the application of X-ray photoemission electron microscopy (X-PEEM) used for the analysis of carbon thin films. We present the results of an X-ray absorption near edge structure (XANES) study of CVD diamond, a-C and CNx films on Si (100) as well as a defect analysis of a hard disc scratch test. The sp(2)/sp(3) ratio of the carbon films was determined and mapped in the electron micrographs, which show localized defects in the surface. (C) 2002 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Ziethen2002,
      author = {Ziethen, C. and Wegelin, F. and Schönhense, G. and Ohr, R. and Neuhauser, M. and Hilgers, H.},
      title = {Soft X-ray photoelectron microscopy used for the characterization of diamond, a-C and CNx, thin films},
      journal = {Diamond And Related Materials},
      publisher = {Elsevier Science Sa},
      year = {2002},
      volume = {11},
      number = {3-6},
      pages = {1068--1073},
      doi = {http://dx.doi.org/10.1016/S0925-9635(01)00597-0}
    }
    
    Fecher, G.H., Schmied, B., Oelsner, A. & Schönhense, G. Temperature-dependent angular resolved UV-photoemission spectroscopy from CeNi2Ge2 2001 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 114, pp. 747-752 
    article DOI  
    Abstract: Pronounced temperature effects in angular resolved ultraviolet photoelectron spectroscopy from the (001) surface of the ternary heavy fermion compound CeNi2Ge2 are presented. The measurements were performed on atomically clean and well-ordered thin films grown on a W(110) substrate. A strongly enhanced intensity at the Fermi edge (E-F) is observed at low-temperatures if the spectra are excited by means of HeI light (hv=21.2 eV). In addition, the work function is dramatically increased with temperature, exhibiting an unusually high positive temperature coefficient of about 0.65 meV/K. The observed temperature dependency suggests a strong redistribution of the states near the Fermi-energy with increasing temperature. A simple model will be given that correlates the observed intensity changes at E-F with the change of the work function. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Fecher2001,
      author = {Fecher, G. H. and Schmied, B. and Oelsner, A. and Schönhense, G.},
      title = {Temperature-dependent angular resolved UV-photoemission spectroscopy from CeNi2Ge2},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {114},
      pages = {747--752},
      doi = {http://dx.doi.org/10.1016/S0368-2048(00)00355-8}
    }
    
    Fecher, G.H., Morais, J., Liesegang, J., Braun, J., Cherepkov, N.A., Oelsner, A., Gunther, M., Schicketanz, M. & Schönhense, G. Spin polarisation and dichroism in ARUPS from thin rare earth films 2001 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 114, pp. 1171-1177 
    article DOI  
    Abstract: In the present study, spin polarisation and dichroism were investigated in angular resolved VUV photoemission ARUPS from magnetised as well as paramagnetic rare earth surfaces. Thin Gd(0001) films were prepared epitaxially on W(110). The photoelectrons were excited by polarised synchrotron radiation from the BESSY I synchrotron radiation source. A SPLEED detector attached to an electron spectrometer mounted on a single axis goniometer was used for angular resolved spin analysis. The main part of this work focused on the characteristic surface state of Gd(0001) which shows a splitting, as previously observed by linear magnetic dichroism and spin polarised photoemission. The spin analysis shows that the two observed states have opposite spin characters. Additionally, the non-magnetic circular dichroism suggests j=3/2 character for the surface state. The experimental findings are compared to atomic models and one-step photoemission calculations. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Fecher2001a,
      author = {Fecher, G. H. and Morais, J. and Liesegang, J. and Braun, J. and Cherepkov, N. A. and Oelsner, A. and Gunther, M. and Schicketanz, M. and Schönhense, G.},
      title = {Spin polarisation and dichroism in ARUPS from thin rare earth films},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {114},
      pages = {1171--1177},
      doi = {http://dx.doi.org/10.1016/S0368-2048(00)00404-7}
    }
    
    Merkel, M., Escher, M., Settemeyer, J., Funnemann, D., Oelsner, A., Ziethen, C., Schmidt, O., Klais, M. & Schönhense, G. Microspectroscopy and spectromicroscopy with photoemission electron microscopy using a new kind of imaging energy filter 2001 Surface Science
    Vol. 480(3), pp. 196-202 
    article DOI  
    Abstract: The use of an imaging retarding field analyser attached to the FOCUS IS-PEEM is described. This kind of energy filter is a simple, powerful tool to obtain microspectra from areas of down to about 1 mum using (V)UV and X-ray excitation sources. First results of microspectroscopy measured by excitation with a laboratory as well as a synchrotron X-ray source are presented. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Merkel2001,
      author = {Merkel, M. and Escher, M. and Settemeyer, J. and Funnemann, D. and Oelsner, A. and Ziethen, C. and Schmidt, O. and Klais, M. and Schönhense, G.},
      title = {Microspectroscopy and spectromicroscopy with photoemission electron microscopy using a new kind of imaging energy filter},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {480},
      number = {3},
      pages = {196--202},
      doi = {http://dx.doi.org/10.1016/S0039-6028(01)00835-4}
    }
    
    Morais, J., Oelsner, A., Schönhense, G., Fecher, G.H., Landers, R., de Siervo, A. & Kleiman, G.G. Photoemission from Pt(111)-(hex)-Rb and Pt(111)-(4x1)-RbO using polarised synchrotron radiation 2001 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 114, pp. 345-350 
    article DOI  
    Abstract: In various experiments it has been demonstrated that the circular dichroism in the angular distribution of photoelectrons (CDAD) is not only observed from oriented initial states (aligned adsorbed molecules or magnetised samples), but also arises as a consequence of the scattering of photoelectrons from the surrounding atoms in a solid or an adsorbate. In this work we will show first measurements performed at the SGM beamline of the Brazilian Synchrotron Light Source (LNLS) on a (4 x 1) superstructure of 1 ML RbO adsorbed on Pt(lll). Measurements from the 4s core levels of Rb adsorbed at Pt(lll) were also performed at the PM-III beamline at BESSY. The measured variations of the intensity and the CDAD with respect to the photon energy are interpreted in terms of photoelectron diffraction. The results will be used to discuss the possibility of photoelectron holography using circularly polarised light. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Morais2001,
      author = {Morais, J. and Oelsner, A. and Schönhense, G. and Fecher, G. H. and Landers, R. and de Siervo, A. and Kleiman, G. G.},
      title = {Photoemission from Pt(111)-(hex)-Rb and Pt(111)-(4x1)-RbO using polarised synchrotron radiation},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {114},
      pages = {345--350},
      doi = {http://dx.doi.org/10.1016/S0368-2048(00)00297-8}
    }
    
    Nepijko, S.A., Sedov, N.N., Schmidt, O., Schönhense, G., Bao, X. & Huang, W. Imaging of three-dimensional objects in emission electron microscopy 2001 Journal Of Microscopy-Oxford
    Vol. 202, pp. 480-487 
    article DOI  
    Abstract: Under investigation by emission electron microscopy, the shape and size of three-dimensional objects are distorted because of the appearance of a characteristic potential relief and a possible contact potential difference between the particles and the substrate. An estimation of these effects for spherical particles is made. It is shown that the apparent size of particles observed in an emission electron microscope (EEM) could be increased as well as decreased depending on the relation between the work functions of the particle and the substrate. The corresponding formulae are given and several possibilities are shown which permit us to determine from the EEM image the real size of particles and their work function relative to the substrate.
    BibTeX:
    @article{Nepijko2001,
      author = {Nepijko, S. A. and Sedov, N. N. and Schmidt, O. and Schönhense, G. and Bao, X. and Huang, W.},
      title = {Imaging of three-dimensional objects in emission electron microscopy},
      journal = {Journal Of Microscopy-Oxford},
      publisher = {Blackwell Science Ltd},
      year = {2001},
      volume = {202},
      pages = {480--487},
      doi = {http://dx.doi.org/10.1046/j.1365-2818.2001.00846.x}
    }
    
    Nepijko, S.A., Sedov, N.N. & Schönhense, G. Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode 2001 Journal Of Microscopy-Oxford
    Vol. 203, pp. 269-276 
    article DOI  
    Abstract: Measurements performed in an electron microscope with the mirror operation mode are most sensitive to local electric fields and geometrical roughness of any kind of the object being studied. The object with a geometrical relief is equivalent to a smooth surface with an effective distribution of microfields. Electrons forming the image interact with the local microfields; for an extended time: during approach to the object, deceleration and acceleration away from the object. As a result, the electron trajectories can be strongly distorted, and the contrast changes essentially, leading to image deformation of details of the object under investigation and to lowering of the resolution. These effects are theoretically described and are illustrated by experiments. An analysis of these effects enables the real size and the shape of the object involved to be reconstructed.
    BibTeX:
    @article{Nepijko2001a,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G.},
      title = {Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode},
      journal = {Journal Of Microscopy-Oxford},
      publisher = {Blackwell Science Ltd},
      year = {2001},
      volume = {203},
      pages = {269--276},
      doi = {http://dx.doi.org/10.1046/j.1365-2818.2001.00895.x}
    }
    
    Oelsner, A., Schmidt, O., Schicketanz, M., Klais, M., Schönhense, G., Mergel, V., Jagutzki, O. & Schmidt-Bocking, H. Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy 2001 Review Of Scientific Instruments
    Vol. 72(10), pp. 3968-3974 
    article DOI  
    Abstract: A method for microspectroscopy and energy-selective imaging using a special photoemission electron microscope (PEEM) is presented. A modified commercial PEEM was combined with a delay line device as x, y, t detector serving as the basic arrangement for spectromicroscopy. One can measure the time of flight of the electrons passing a drift section in order to analyze the energy distribution of photoelectrons in PEEM. The time of flight is referenced to the time structure of the synchrotron radiation from an electron storage ring. At electron kinetic energies of less than 20 eV within the drift region a spatial resolution of about 100 nm has been obtained. Fast counting electronics (instead of a camera) delivers an image for real-time monitoring on an oscilloscope screen or for image acquisition by a computer. A time resolution of about 500 ps has been obtained with the potential of further improvement. The spatial resolution of the delay line detector is about 50 mum in the image plane corresponding to 1000 pixels in the image diagonal. Direct photoemission from the W-4f core level of a W(110) single-crystal sample was observed at several photon energies. The W-4f fine-structure splitting of 2.3 eV could be well resolved at a pass energy around 40 eV through the drift region. (C) 2001 American Institute of Physics.
    BibTeX:
    @article{Oelsner2001,
      author = {Oelsner, A. and Schmidt, O. and Schicketanz, M. and Klais, M. and Schönhense, G. and Mergel, V. and Jagutzki, O. and Schmidt-Bocking, H.},
      title = {Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy},
      journal = {Review Of Scientific Instruments},
      publisher = {Amer Inst Physics},
      year = {2001},
      volume = {72},
      number = {10},
      pages = {3968--3974},
      doi = {http://dx.doi.org/10.1063/1.1405781}
    }
    
    Ohr, R., Neuhäuser, M., Hilgers, H., Pokrowsky, P., Schönhense, G. & Dittmar, G. Ellipsometrische Charakterisierung von C-Schutzschichten für die Speichertechnologie 2001 Vakuum in Forschung und Praxis
    Vol. 13 , pp. 277-285 
    article  
    BibTeX:
    @article{Ohr2001,
      author = {Ohr, R. and Neuhäuser,M. and Hilgers, H. and Pokrowsky, P. and Schönhense, G. and Dittmar, G.},
      title = {Ellipsometrische Charakterisierung von C-Schutzschichten für die Speichertechnologie},
      journal = {Vakuum in Forschung und Praxis},
      year = {2001},
      volume = {13 },
      pages = {277-285}
    }
    
    Schicketanz, M., Oelsner, A., Morais, J., Mergel, V., Schmidt-Bocking, H. & Schönhense, G. Electron-TOF-analyser for complete momentum analysis in photoemission from surfaces 2001 Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
    Vol. 467-468(Part 2), pp. 1519-1522 
    article DOI  
    Abstract: We present a new method for momentum-selective imaging by means of a time-of-flight (TOF) technique. The instrument employs a time- and space-resolving delayline detector in combination with a parabolic electrostatic field and a drift space. We use this kind of spectrometer, to raise the efficiency of experiments, which are total momentum resolved. The main difference to conventional photoemission experiments using a rotatable spectrometer is the simultaneous detection of all emitted photoelectrons. In addition to this feature, the angular distribution should be directly visible, to observe solid state symmetries. In order to facilitate these requirements, we use a delayline detector as a position and time sensitive device with a versatile user interface. First results obtained at BESSY I are presented.
    BibTeX:
    @article{Schicketanz2001,
      author = {Schicketanz, M. and Oelsner, A. and Morais, J. and Mergel, V. and Schmidt-Bocking, H. and Schönhense, G.},
      title = {Electron-TOF-analyser for complete momentum analysis in photoemission from surfaces},
      journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
      year = {2001},
      volume = {467-468},
      number = {Part 2},
      pages = {1519--1522},
      doi = {http://dx.doi.org/10.1016/S0168-9002(01)00743-4}
    }
    
    Schmidt, O., Fecher, G.H., Hwu, Y. & Schönhense, G. The spatial distribution of non-linear effects in multi-photon photoemission from metallic adsorbates on Si(1 1 1) 2001 Surface Science
    Vol. 482-485(Part 1), pp. 687-692 
    article DOI  
    Abstract: Multi-photon excitations from thin metallic films on silicon substrates have been observed utilising photoemission electron microscopy. The photoelectrons have been excited by means of high power femtosecond laser pulses with a photon energy below the work function threshold. The strong spatial variations of the non-linear effects became directly visible in electron emission from the adsorbed thin films. Centres of enhanced photoelectron yield, so-called hot spots, were observed on the surfaces of various samples. The multi-photon electron yield of the metallic films (permalloy and lead) depends strongly on the sample topography and the photon polarisation.
    BibTeX:
    @article{Schmidt2001,
      author = {Schmidt, O. and Fecher, G. H. and Hwu, Y. and Schönhense, G.},
      title = {The spatial distribution of non-linear effects in multi-photon photoemission from metallic adsorbates on Si(1 1 1)},
      journal = {Surface Science},
      year = {2001},
      volume = {482-485},
      number = {Part 1},
      pages = {687--692},
      doi = {http://dx.doi.org/10.1016/S0039-6028(01)00926-8}
    }
    
    Schneider, C.M., de Haas, O., Muschiol, U., Cramer, N., Oelsner, A., Klais, M., Schmidt, O., Fecher, G.H., Jark, W. & Schönhense, G. Photoemission microscopy from magnetically coupled thin-film systems 2001 Journal Of Magnetism And Magnetic Materials
    Vol. 233(1-2), pp. 14-20 
    article DOI  
    Abstract: The magnetic microstructure and magnetic coupling phenomena in thin-film systems, relevant for applications in magneto-electronics, are investigated by means of photoemission electron microscopy. Element-selective magnetic information is obtained by exploiting magnetic circular dichroism in the soft X-ray regime. The domain shape and sizes found at the surface of anti ferromagnetically coupled metallic multilayers indicate the presence of a ferromagnetic coupling contribution, presumably caused by a build-up of roughness during the growth process, The magnetic domain patterns in FeNi microstructures on sputtered NiO films reflect the presence of a local exchange anisotropy, causing the phenomenon of exchange biasing or pinning of the ferromagnetic layer. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Schneider2001,
      author = {Schneider, C. M. and de Haas, O. and Muschiol, U. and Cramer, N. and Oelsner, A. and Klais, M. and Schmidt, O. and Fecher, G. H. and Jark, W. and Schönhense, G.},
      title = {Photoemission microscopy from magnetically coupled thin-film systems},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {233},
      number = {1-2},
      pages = {14--20},
      doi = {http://dx.doi.org/10.1016/S0304-8853(01)00219-0}
    }
    
    Schönhense, G., Oelsner, A., Schmidt, O., Fecher, G.H., Mergel, V., Jagutzki, O. & Schmidt-Bocking, H. Time-of-flight photoemission electron microscopy - a new way to chemical surface analysis 2001 Surface Science
    Vol. 480(3), pp. 180-187 
    article DOI  
    Abstract: The time structure of synchrotron radiation at BESSY I (Berlin) was utilised to operate a photoemission electron microscope in the time-of-flight mode. The electrons that are emitted from the sample surface with different energies are dispersed in a drift tube subsequent to the imaging optics. Two ways of fast image detection have been explored, a fast gated intensified CCD camera (800 ps gate time) and a special counting electronics in combination with a 3D (x,y,t)-resolving delay line detector (time resolution < 500 ps). The latter device has a lateral resolution of about 50 mum in the image plane being equivalent to 1000 pixels along the image diagonal. An energy resolution of 400 meV has been achieved. The future potential of time-resolving photoemission microscopy is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Schoenhense2001,
      author = {Schönhense, G. and Oelsner, A. and Schmidt, O. and Fecher, G. H. and Mergel, V. and Jagutzki, O. and Schmidt-Bocking, H.},
      title = {Time-of-flight photoemission electron microscopy - a new way to chemical surface analysis},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {2001},
      volume = {480},
      number = {3},
      pages = {180--187},
      doi = {http://dx.doi.org/10.1016/S0039-6028(01)00833-0}
    }
    
    Schönhense, G. Magnetic Domain Imaging of Thin Metallic Layers Using PEEM 2001 Physics of Low Dimensional Systems, pp. 309 – 333  incollection  
    BibTeX:
    @incollection{Schoenhense2001a,
      author = {Schönhense, G.},
      title = {Magnetic Domain Imaging of Thin Metallic Layers Using PEEM},
      booktitle = {Physics of Low Dimensional Systems},
      publisher = {Kluwer Academic/Plenum Publishers, New York},
      year = {2001},
      pages = {309 – 333},
      edition = {1}
    }
    
    Singleton, L., Baron, R., Marx, G.K.L., Schönhense, G. & Schmidt, A. Fabrication of a miniaturised objective lens for a Photoemission Electron Microscope (PEEM) 2001 Conference Proceedings Microtec 2000, Hannover, pp. 699-704  inproceedings  
    BibTeX:
    @inproceedings{Singleton2001,
      author = {Singleton, L. and Baron, R. and Marx, G. K. L. and Schönhense, G. and Schmidt, A.},
      title = {Fabrication of a miniaturised objective lens for a Photoemission Electron Microscope (PEEM)},
      booktitle = {Conference Proceedings Microtec 2000, Hannover},
      year = {2001},
      pages = {699-704}
    }
    
    Wegelin, F., Ziethen, C., Schönhense, G., Neuhäuser, M., Ohr, R. & Hilgers, H. Defektanalyse von a-C- und CNx-Schichten mittels Röntgen-Photoemissions-Elektronenmikroskopie (X-PEEM) 2001 Vakuum in Forschung und Praxis
    Vol. 13, pp. 287-292 
    article  
    BibTeX:
    @article{Wegelin2001,
      author = {Wegelin, F. and Ziethen, Ch. and Schönhense, G. and Neuhäuser, M. and Ohr, R. and Hilgers, H.},
      title = {Defektanalyse von a-C- und CNx-Schichten mittels Röntgen-Photoemissions-Elektronenmikroskopie (X-PEEM)},
      journal = {Vakuum in Forschung und Praxis},
      year = {2001},
      volume = {13},
      pages = {287-292}
    }
    
    Getzlaff, M., Westphal, C., Bansmann, J. & Schönhense, G. Chalcogen adsorption and surface magnetism 2000 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 107(3), pp. 293-300 
    article DOI  
    Abstract: Investigations concerning the electronic and magnetic properties of oxygen and sulfur adsorbed on magnetized surfaces were carried out by means of angle and spin resolving photoelectron spectroscopy. Iron(110), a polycrystalline iron alloy, and an amorphous metallic glass (Fe79B16Si5) served as ferromagnetic substrates. Exchange splittings of the O 2p and S 3p derived levels could be detected, demonstrating a magnetic coupling between the chemisorbate and iron. This observation presents a prerequisite for an induced magnetic moment within the adsorbate overlayer. For sulfur an adsorbate-induced structure only in the minority spin channel near the Fermi level was observed which was predicted by theoretical calculations. This feature is localized in the topmost iron layer. (C) 2000 Elsevier Science BN. All rights reserved.
    BibTeX:
    @article{Getzlaff2000,
      author = {Getzlaff, M. and Westphal, C. and Bansmann, J. and Schönhense, G.},
      title = {Chalcogen adsorption and surface magnetism},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2000},
      volume = {107},
      number = {3},
      pages = {293--300},
      doi = {http://dx.doi.org/10.1016/S0368-2048(00)00181-X}
    }
    
    Marx, G.K.L., Elmers, H.J. & Schönhense, G. Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films 2000 Physical Review Letters
    Vol. 84(25), pp. 5888-5891 
    article DOI  
    Abstract: Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A = (0.37 +/- 0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.
    BibTeX:
    @article{Marx2000,
      author = {Marx, G. K. L. and Elmers, H. J. and Schönhense, G.},
      title = {Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films},
      journal = {Physical Review Letters},
      publisher = {American Physical Soc},
      year = {2000},
      volume = {84},
      number = {25},
      pages = {5888--5891},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.84.5888}
    }
    
    Nepijko, S.A., Sedov, N.N. & Schönhense, G. Measurement of magnetic fields and domain structures using a photoemission electron microscope 2000 Advances In Imaging And Electron Physics, Vol 113
    Vol. 113, pp. 205-248 
    article  
    BibTeX:
    @article{Nepijko2000,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G.},
      title = {Measurement of magnetic fields and domain structures using a photoemission electron microscope},
      journal = {Advances In Imaging And Electron Physics, Vol 113},
      publisher = {Academic Press Inc},
      year = {2000},
      volume = {113},
      pages = {205--248}
    }
    
    Nepijko, S.A., Sedov, N.N., Schönhense, G., Escher, M., Bao, X.H. & Huang, W.X. Resolution deterioration in emission electron microscopy due to object roughness 2000 Annalen Der Physik
    Vol. 9(6), pp. 441-451 
    article DOI  
    Abstract: In the present paper a general analytic expression has been obtained and confirmed by a computer simulation which links the surface roughness of an object under study in an emission electron microscope and it's resolution. A quantitative derivation was made for the model case when there is a step on the object surface. It was shown that the resolution is deteriorated asymmetrically relative to the step. The effect sets a practical limit to the ultimate lateral resolution obtainable in an emission electron microscope.
    BibTeX:
    @article{Nepijko2000a,
      author = {Nepijko, S. A. and Sedov, N. N. and Schönhense, G. and Escher, M. and Bao, X. H. and Huang, W. X.},
      title = {Resolution deterioration in emission electron microscopy due to object roughness},
      journal = {Annalen Der Physik},
      publisher = {Wiley-V C H Verlag Gmbh},
      year = {2000},
      volume = {9},
      number = {6},
      pages = {441--451},
      doi = {http://dx.doi.org/10.1002/1521-3889(200006)9:6<441::AID-ANDP441>3.0.CO;2-J}
    }
    
    Nepijko, S.A., Sedov, N.N., Ziethen, C., Schönhense, G., Merkel, M. & Escher, M. Peculiarities of imaging one- and two-dimensional structures in an emission electron microscope. 1. Theory 2000 Journal Of Microscopy
    Vol. 199, pp. 124-129 
    article DOI  
    Abstract: Local changes in work function cause deviations of the electrical microfield near a sample surface as a result of the uniform accelerating field distribution between the sample (cathode) and the extractor electrode (anode). This results in a change in the electron trajectories. As a consequence, the microscope image shows remarkable changes in position, size, intensity and lateral resolution of distinct details, which can be quantitatively described by the calculations presented here. Analysing these effects in the image gives an opportunity to determine the real lateral size of the observed structures and the distribution of local contact potentials.
    BibTeX:
    @article{Nepijko2000b,
      author = {Nepijko, S. A. and Sedov, N. N. and Ziethen, C. and Schönhense, G. and Merkel, M. and Escher, M.},
      title = {Peculiarities of imaging one- and two-dimensional structures in an emission electron microscope. 1. Theory},
      journal = {Journal Of Microscopy},
      publisher = {Blackwell Science Ltd},
      year = {2000},
      volume = {199},
      pages = {124--129},
      doi = {http://dx.doi.org/10.1046/j.1365-2818.2000.00713.x}
    }
    
    Schmitt, T., Guttmann, P., Schmidt, O., Müller-Buschbaum, P., Stamm, M., Schönhense, G. & Schmahl, G. Microscopy of Thin Polymer Blend Films of Polystyrene and Poly-n-buty-methacrylate 2000 X-Ray Microscopy: Proceedings of the Sixth International Conference Berkeley, CA, 2-6 August 1999, pp. 245-249  inproceedings URL 
    BibTeX:
    @inproceedings{Schmitt2000,
      author = {Schmitt, T. and Guttmann, P. and Schmidt, O. and Müller-Buschbaum, P. and Stamm, M. and Schönhense, G. and Schmahl, G.},
      title = {Microscopy of Thin Polymer Blend Films of Polystyrene and Poly-n-buty-methacrylate},
      booktitle = {X-Ray Microscopy: Proceedings of the Sixth International Conference Berkeley, CA, 2-6 August 1999},
      publisher = {AIP Press},
      year = {2000},
      pages = {245-249},
      edition = {1},
      url = {http://amazon.de/o/ASIN/1563969262/}
    }
    
    Semenov, S.K., Cherepkov, N.A., Fecher, G.H. & Schönhense, G. Generalization of the atomic random-phase-approximation method for diatomic molecules: N-2 photoionization cross-section calculations 2000 Physical Review A
    Vol. 61(3), pp. 032704 
    article DOI  
    Abstract: Partial and total photoionization cross sections of N-2 molecule are calculated using the generalization of the random-phase approximation (RPA) which earlier has been successfully applied to the description of the atomic photoionization processes. According to this method, at first the Hartree-Fock (HF) ground-state wave functions are calculated in prolate spheroidal coordinates using the fixed-nuclei approximation. With their help the zero order basis set of single particle Hartree-Fock wave functions containing both discrete excited states and continuous spectrum is calculated in the field of a frozen core of a singly charged ion. The calculations are performed for all four valence shells of N-2 molecule, 3 sigma(g), 1 pi(u), 2 sigma(u), and 2 sigma(g), with the intershell correlations fully taken into account within the RPA method. It is demonstrated that different intershell correlations. especially between three outer shells, play an important role in photoionization process. Examples of the influence of intershell correlations on several transitions sire presented. Partial and total photoionization cross sections of N-2 molecule obtained by this method in the photon energy range from ionization threshold up to 70 eV are in a good agreement with the existing experimental data and with, the recent RPA calculations [Cacelli et al., Phys. Rev. A 57, 1895 (1998)].
    BibTeX:
    @article{Semenov2000,
      author = {Semenov, S. K. and Cherepkov, N. A. and Fecher, G. H. and Schönhense, G.},
      title = {Generalization of the atomic random-phase-approximation method for diatomic molecules: N-2 photoionization cross-section calculations},
      journal = {Physical Review A},
      publisher = {American Physical Soc},
      year = {2000},
      volume = {61},
      number = {3},
      pages = {032704},
      doi = {http://dx.doi.org/10.1103/PhysRevA.61.032704}
    }
    
    Singleton, L., Ansel, Y., Baron, R., Marx, G., Nienhaus, M., Schmitz, F., Schönhense, G. & Schmidt, A. Miniaturized Objective Lens for a Photoelectron Emission Microscope 2000 SPIE proceedings series
    Vol. 4179Micromachining technology for micro-optics, Santa Clara, USA, pp. 146-157 
    inproceedings  
    BibTeX:
    @inproceedings{Singleton2000,
      author = {Singleton, L. and Ansel, Y. and Baron, R. and Marx, G.K.L. and Nienhaus, M. and Schmitz, F. and Schönhense, G. and Schmidt, A.},
      title = {Miniaturized Objective Lens for a Photoelectron Emission Microscope},
      booktitle = {Micromachining technology for micro-optics, Santa Clara, USA},
      journal = {SPIE proceedings series},
      publisher = {SPIE},
      year = {2000},
      volume = {4179},
      pages = {146-157}
    }
    
    Ziethen, C., Schmidt, O., Marx, G.K.L., Schonhense, G., Fromter, R., Gilles, J., Kirschner, J., Schneider, C.M. & Groning, O. Orbital mapping of carbon thin films by XANES-spectromicroscopy 2000 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 107(3), pp. 261-271 
    article DOI  
    Abstract: A laterally resolved micro-XANES study (X-ray absorption near edge structure) of amorphous carbon, hydrogen terminated CVD-diamond (100) and highly oriented pyrolytic graphite (HOPG) is presented. The results were obtained by means of a photoemission electron microscope. Using this technique the well-known spectral features of carbon in its different chemical states (sp(2), sp(3)) could be recorded. The sp(2)/sp(3) content of the films was extracted from the spectra. Images, taken at X-ray energies corresponding to maxima (pi*, C-H*) of the unoccupied density of states in these spectra, map the lateral distribution of the different orbitals at the sample surface. This study revealed graphitic areas on a well-ordered diamond surface and shows the location of C-H bonds on edges of the basal plane of the HOPG. Profiting from the elemental selectivity of the method, even weak traces of iron contaminations are mapped at the diamond surface. (C) 2000 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Ziethen2000,
      author = {Ziethen, C. and Schmidt, O. and Marx, G. K. L. and Schonhense, G. and Fromter, R. and Gilles, J. and Kirschner, J. and Schneider, C. M. and Groning, O.},
      title = {Orbital mapping of carbon thin films by XANES-spectromicroscopy},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {2000},
      volume = {107},
      number = {3},
      pages = {261--271},
      doi = {http://dx.doi.org/10.1016/S0368-2048(00)00151-1}
    }
    
    Fecher, G.H., Braun, J., Cherepkov, N.A., Chernysheva, L.V., Jentzsch, T., Morais, J., Oelsner, A., Ostertag, C., Paul, J., Ufer, H. & Schönhense, G. Dichroism in angular resolved VUV-photoemission from the (0001) surfaces of thin Gd and Nd films epitaxially grown on W(110) 1999 European Physical Journal B
    Vol. 11(1), pp. 161-175 
    article DOI  
    Abstract: We present investigations of the electronic and magnetic structure of the Rare Earth valence states. In particular, we have examined ultra thin films (less than or equal to 10 ML) of the rare earth metals gadolinium and neodymium epitaxially grown on tungsten (110). Various experiments on dichroism in angular resolved photoemission have been performed using circularly as well as linearly polarised light in the VUV-range with photon energies below 40 eV. A special emphasis was placed on the investigation of the surface state, which nas observed for both Gd and Nd. A very small magnetic splitting of about 25 meV was observed for the surface state of ferromagnetic Gd. A magnetic ordering of a Nd-monolayer on a remanently magnetised Fe-film is observed. Large dichroism effects are found for the surface state as well as the valence bands of paramagnetic Nd. In the latter case, these are used to determine the dispersion of the valence bands. Different numerical approaches are presented, one based on atomic photoionisation theory, another is based on a one-step model of solid state photoemission. Atomic photoionisation theory is used together with three-step calculations to explain the non-magnetic circular dichroism observed in the Gd 4f emission. The capability of dichroism experiments for resolving details of the electronic structure and for sensitive tests of photoemission calculations is demonstrated.
    BibTeX:
    @article{Fecher1999,
      author = {Fecher, G. H. and Braun, J. and Cherepkov, N. A. and Chernysheva, L. V. and Jentzsch, T. and Morais, J. and Oelsner, A. and Ostertag, C. and Paul, J. and Ufer, H. and Schönhense, G.},
      title = {Dichroism in angular resolved VUV-photoemission from the (0001) surfaces of thin Gd and Nd films epitaxially grown on W(110)},
      journal = {European Physical Journal B},
      publisher = {Springer Verlag},
      year = {1999},
      volume = {11},
      number = {1},
      pages = {161--175},
      doi = {http://dx.doi.org/10.1007/s100510050926}
    }
    
    Fecher, G.H., Schmied, B. & Schönhense, G. Temperature-dependent ARUPS from the heavy fermion compound CeNi2Ge2(001) 1999 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 103, pp. 771-776 
    article DOI  
    Abstract: Angular resolved ultraviolet photoelectron spectroscopy is presented for the (001) surface of the ternary heavy fermion compound CeNi2Ge2. The samples are atomically clean and well-ordered thin films grown on a W(110) substrate under UHV-condition. The temperature was varied between 10 K and 300 K. The spectra were excited by means of HeI light (hv=21.2 eV). An enhanced intensity near the Fermi edge is observed at low temperatures for this excitation energy. With the variation of the detection angle, not only a change of the intensity but also of the position of the signal near the Fermi edge was observed. Furthermore the work function is drastically lowered, exhibiting an unusually high positive temperature coefficient of about 0.65 meV/K. (C) 1999 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Fecher1999a,
      author = {Fecher, G. H. and Schmied, B. and Schönhense, G.},
      title = {Temperature-dependent ARUPS from the heavy fermion compound CeNi2Ge2(001)},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1999},
      volume = {103},
      pages = {771--776},
      doi = {http://dx.doi.org/10.1016/S0368-2048(98)00365-X}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Oxygen on Fe(110): magnetic properties of the adsorbate system 1999 Journal Of Magnetism And Magnetic Materials
    Vol. 192(3), pp. 458-466 
    article DOI  
    Abstract: Investigations concerning the electronic and magnetic properties of oxygen adsorbed on magnetized iron films were carried out by means of angle and spin resolving photoelectron spectroscopy. Iron(1 1 0), epitaxially grown on a W(1 1 0) crystal, served as the ferromagnetic substrate. Exchange splittings of the O 2p(x) derived level were detected demonstrating a magnetic coupling between the chemisorbate and the iron layer. This observation indicates the presence of an induced magnetic moment within the adsorbate overlayer. Variations of the exchange splitting occurred as a function of the oxygen coverage, energy of the exciting radiation, and detection angle of the emitted photoelectrons pointing to a k(parallel to)-dependent exchange splitting. High oxygen exposures lead to a FeO overlayer at the surface, showing vanishing peak separations due to the antiferromagnetic behavior of iron oxide. (C) 1999 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Getzlaff1999,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Oxygen on Fe(110): magnetic properties of the adsorbate system},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {1999},
      volume = {192},
      number = {3},
      pages = {458--466},
      doi = {http://dx.doi.org/10.1016/S0304-8853(98)00686-6}
    }
    
    Grahneis, W., Ziethen, C., Fecher, G.H. & Schönhense, G. Combined chemical microanalysis using SAM and X-PEEM 1999 Japanese Journal Of Applied Physics Part 1-Regular Papers Short Notes & Review Papers
    Vol. 38, pp. 317-320 
    article URL 
    Abstract: Both, PEEM (Photoemission Microscopy) and SAM (Scanning Auger Microprobe) are surface sensitive techniques providing spatially resolved chemical analysis. We compare these techniques and present results on thin High Temperature Superconductor firms. The X-PEEM makes use of tuneable monochromatised soft X-rays from a synchrotron radiation source to excite electrons from core levels. A higher secondary electron yield is observed when tuning the source above one of the characteristic absorption edges. These true secondaries are detected with the electron microscope in parallel imaging mode. Therefore, PEEM gives besides the imaging additional information on the chemical bonding and its local order making use of NEXAFS and EXAFS spectroscopies.
    BibTeX:
    @article{Grahneis1999,
      author = {Grahneis, W. and Ziethen, C. and Fecher, G. H. and Schönhense, G.},
      title = {Combined chemical microanalysis using SAM and X-PEEM},
      journal = {Japanese Journal Of Applied Physics Part 1-Regular Papers Short Notes & Review Papers},
      publisher = {Japan J Applied Physics},
      year = {1999},
      volume = {38},
      pages = {317--320},
      url = {http://jjap.ipap.jp/link?JJAPS/38S1/317}
    }
    
    Kleineberg, U., Menke, D., Hamelmann, F., Heinzmann, U., Schmidt, O., Fecher, G.H. & Schönhense, G. Photoemission microscopy with microspot-XPS by use of undulator radiation and a high-throughput multilayer monochromator at BESSY 1999 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 103, pp. 931-936 
    article DOI  
    Abstract: We present a new experiment for photoelectron microspectroscopy by use of undulator radiation, which has been set up at the beamline U2 at the Berlin electron storage ring BESSY 1. This approach employs a non-imaging simulated hemispherical electron energy analyser attached to an imaging photoemission electron microscope (FOCUS IS-PEEM) with integrated microarea selector. The photoemission microscope exhibits a lateral resolution of 25 nm (with 4.9 eV UV-excitation), while the resolution with incident synchrotron radiation in the soft X-ray range is about 100-120 nm (mainly due to chromatic aberrations). Photoemission microscopy as well as photoelectron microspectroscopy of selected areas on the sample surface were performed by using the third harmonic of the direct undulator beam which was monochromatized and refocused by a two-element multilayer optic in the 70-95 eV energy range. The multilayer monochromator operating at near-normal incidence consists of a concave spherical multilayer mirror (r=650 mm) and a plane multilayer grating (blazed grating 1221 L/mm, blaze angle 0.8 deg). Both elements were coated with a Mo/Si multilayer of equal d-spacing (20 doublelayers, d = 10.5 nm) to enhance the reflectivity for EUV radiation at near-normal incidence angles. The characterization of the individual optical components by EUV reflectometry shows a peak reflectance of about 47% at a photon energy of 95 eV in the case of the focusing multilayer mirror while the first order diffraction efficiency of the multilayer blaze grating was measured to be up to 32%. The evaluation of the photoelectron spectra measured with this set-up displays that the spectral resolution of the incident radiation is better than 0.7 eV, while it is about 2-4 eV in the case of a two-multilayer-mirror configuration. Analysis of the surface topography and the chemical composition of inhomogeneities of thin evaporated layers on a mesoscopic scale are the main applications of this experiment. (C) 1999 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Kleineberg1999,
      author = {Kleineberg, U. and Menke, D. and Hamelmann, F. and Heinzmann, U. and Schmidt, O. and Fecher, G. H. and Schönhense, G.},
      title = {Photoemission microscopy with microspot-XPS by use of undulator radiation and a high-throughput multilayer monochromator at BESSY},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1999},
      volume = {103},
      pages = {931--936},
      doi = {http://dx.doi.org/10.1016/S0368-2048(98)00374-0}
    }
    
    Kuznetsov, V.V., Cherepkov, N.A., Fecher, G.H. & Schönhense, G. Angular distributions of photoelectrons ejected from fixed-in-space molecules of C-3v symmetry group 1999 Journal Of Chemical Physics
    Vol. 110(20), pp. 9997-10007 
    article DOI  
    Abstract: The angular distributions of photoelectrons from fixed-in-space molecules of C-3v symmetry group are studied for the particular case when the light beam is incoming parallel to the C-3 rotational axis of the molecule. The consideration is based on the expansion of photoelectron wave functions in symmetry-adapted spherical harmonics. The analytical equations for the angular distributions of photoelectrons ejected by linearly polarized, circularly polarized, and unpolarized light have been derived. The threefold symmetry of the target reveals itself most clearly for circularly polarized and unpolarized light when the dependence on the azimuthal angle is studied for a fixed polar angle. For linearly polarized light the photoelectron angular distributions have a more complicated dependence on the azimuthal angle. On the other hand, with linearly polarized light one can easily distinguish between the a(1) and a(2) initial states by observing the zeroes of photoelectron intensities in the symmetry plane ejected by light linearly polarized either in the symmetry plane or perpendicular to the symmetry plane. The numerical examples presented in the paper demonstrate the general properties of the angular distributions as well as properties of the circular and linear dichroism in the angular distribution. (C) 1999 American Institute of Physics. [S0021-9606(99)02018-8].
    BibTeX:
    @article{Kuznetsov1999,
      author = {Kuznetsov, V. V. and Cherepkov, N. A. and Fecher, G. H. and Schönhense, G.},
      title = {Angular distributions of photoelectrons ejected from fixed-in-space molecules of C-3v symmetry group},
      journal = {Journal Of Chemical Physics},
      publisher = {Amer Inst Physics},
      year = {1999},
      volume = {110},
      number = {20},
      pages = {9997--10007},
      doi = {http://dx.doi.org/10.1063/1.478873}
    }
    
    Oelsner, A., Fecher, G.H., Schicketanz, M. & Schönhense, G. Determining the optical properties of adsorbate covered surfaces by dichroism in VUV-photoemission 1999 Surface Science
    Vol. 435, pp. 53-57 
    article  
    Abstract: The dichroic effects of photoemission excited by polarised light depend on the angle of photon incidence. Measurements of the difference in the angle-resolved photoemission intensities from Cs 5p semi-corelevels excited by photons of opposite helicity, or of orthogonal linear polarisation are reported. It was thought that the dependence of dichroism on the angle of incidence cannot be described using equations omitting metal optics. A complete consideration of the vector potential of the exciting light is needed, including the phase shift between it's parallel and perpendicular components. The phase shift is produced by the complex index of refraction. Using the Fresnel equations for structureless media, one finds that the second and the third components of the Stokes vector both change their sign, if only the initial helicity or linear polarisation are reversed. The complex index of refraction of a Cs-covered W(110) surface is determined from measurements using the quantitative knowledge of the dichroism effects, that is, CDAD and LDAD. (C) 1999 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Oelsner1999,
      author = {Oelsner, A. and Fecher, G. H. and Schicketanz, M. and Schönhense, G.},
      title = {Determining the optical properties of adsorbate covered surfaces by dichroism in VUV-photoemission},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1999},
      volume = {435},
      pages = {53--57}
    }
    
    Schönhense, G. Imaging of magnetic structures by photoemission electron microscopy 1999 Journal Of Physics-Condensed Matter
    Vol. 11(48), pp. 9517-9547 
    article DOI  
    Abstract: Photoemission electron microscopy (PEEM) has proven to be a powerful analytical tool in surface science. In this contribution, a status report is given on the application of the PEEM technique in the investigation of surface and interface magnetism. Owing to its fast parallel image acquisition and its wide zoom range, allowing fields of view from almost 1 mm down to a few micrometres, combined with a high base resolution of the order of 20 nm, the method offers a unique access to many aspects in surface and thin-film magnetism on the mesoscopic length scale. There are three basically different modes of magnetic imaging using PEEM. The first one exploits the magnetic x-ray circular dichroism (MXCD) for contrast formation. It offers the important advantage of selecting the magnetic contrast of a certain element via the corresponding x-ray absorption edges using a tuneable x-ray source such as synchrotron radiation. This mode gives access to magnetic structures and coupling phenomena with a sensitivity in the submonolayer range and the capability to image the signal of buried layers with an information depth up to more than 5 nm. The two other modes work with simple UV light sources and are therefore highly attractive for standard laboratory applications. The magnetic stray-field-induced changes of the electron trajectories close to the sample surface lead to a Lorentz-type contrast. A third type of contrast arises as a consequence of the Kerr rotation of the dielectric vector inside a magnetic material, a phenomenon which is also responsible for the well known magneto-optical Kerr effect. Examples and typical applications of magnetic imaging using PEEM are discussed.
    BibTeX:
    @article{Schoenhense1999,
      author = {Schönhense, G.},
      title = {Imaging of magnetic structures by photoemission electron microscopy},
      journal = {Journal Of Physics-Condensed Matter},
      publisher = {Iop Publishing Ltd},
      year = {1999},
      volume = {11},
      number = {48},
      pages = {9517--9547},
      doi = {http://dx.doi.org/10.1088/0953-8984/11/48/311}
    }
    
    Bansmann, J., Getzlaff, M., Schönhense, G., Fluchtmann, M. & Braun, J. Valence band photoemission from thin iron films - a comparison of experimental and theoretical results 1998 Surface Science
    Vol. 404(1-3), pp. 365-370 
    article  
    Abstract: In this contribution, we report on photoemission data from thin iron films on W(110) that have been carried out by means of spin-resolved photoelectron spectroscopy as well as Magnetic Circular Dichroism in valence band photoemission at the storage ring BESSY. These techniques give complementary information on the electronic and magnetic properties, such as exchange and spin-orbit splitting. We compare our experimental data to new photoemission calculations, which have been obtained in the framework of a fully relativistic one-step theory for ferromagnetic materials. (C) 1998 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Bansmann1998,
      author = {Bansmann, J. and Getzlaff, M. and Schönhense, G. and Fluchtmann, M. and Braun, J.},
      title = {Valence band photoemission from thin iron films - a comparison of experimental and theoretical results},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {404},
      number = {1-3},
      pages = {365--370}
    }
    
    Fecher, G.H., Oelsner, A., Schicketanz, M. & Schönhense, G. The dependence of dichroism in VUV-photoemission on the optical properties of adsorbates: Cs-monolayer on W(110) 1998 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 88, pp. 185-190 
    article DOI  
    Abstract: We report on the dependence of dichroic photoemission excited by polarised light on the angle of photon incidence. We measured the difference in the angle-resolved photoemission intensities from Cs-Sp semi-corelevels excited by photons of opposite helicity, known as CDAD and of orthogonal linear polarisation-LDAD. We found that the dependence of dichroism on the angle of incidence can not be described by the equations used in the photoemission model for free atomic states. A complex consideration of the parallel and perpendicular components of the vector potential of the exciting light is needed, including the phase shift between these components. The phase shift is produced by the complex index of refraction. Using the Fresnel-equations for structureless media, one finds that in CDAD measurements not only the third component of the Stokes vector is responsible for the differences in the excitation process, but also the second component and vice versa for LDAD. Both Stokes components change the sign if the initial helicity or linear polarisation is reversed resulting in an additional dichroism just of the other kind. (C) 1998 Elsevier Science B.V.
    BibTeX:
    @article{Fecher1998,
      author = {Fecher, G. H. and Oelsner, A. and Schicketanz, M. and Schönhense, G.},
      title = {The dependence of dichroism in VUV-photoemission on the optical properties of adsorbates: Cs-monolayer on W(110)},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {88},
      pages = {185--190},
      doi = {http://dx.doi.org/10.1016/S0368-2048(97)00112-6}
    }
    
    Getzlaff, M., Heidemann, B., Bansmann, J., Westphal, C. & Schönhense, G. A variable-angle electron spin polarization detection system 1998 Review Of Scientific Instruments
    Vol. 69(11), pp. 3913-3923 
    article DOI  
    Abstract: An ultrahigh vacuum apparatus for investigations of ferromagnetic samples allowing the variation of detection angle and spin resolution of secondary and photoelectrons is described. Angle variation is facilitated by a special combination of 180 degrees and 90 degrees deflectors and a cylindrical sector analyzer serves as energy dispersing element. Spin analysis is carried out using a hemispherical high energy (90 keV) Mott polarimeter without retarding potentials. Its efficiency was determined as 2.4 x 10(-4). Due to acceleration in a short spherically symmetric field, the setup is rather compact and the sensitivity to geometrical misalignment is small. The performance of the instrument is demonstrated by angle dependent measurements of thin ferromagnetic Co(0001) films, evaporated on W(110), and modifications of surface magnetic properties of a xenon adsorbate layer. (C) 1998 American Institute of Physics. [S0034-6748(98)01611- 6].
    BibTeX:
    @article{Getzlaff1998,
      author = {Getzlaff, M. and Heidemann, B. and Bansmann, J. and Westphal, C. and Schönhense, G.},
      title = {A variable-angle electron spin polarization detection system},
      journal = {Review Of Scientific Instruments},
      publisher = {Amer Inst Physics},
      year = {1998},
      volume = {69},
      number = {11},
      pages = {3913--3923},
      doi = {http://dx.doi.org/10.1063/1.1149199}
    }
    
    Getzlaff, M., Schmied, B., Wilhelm, M., Kubler, U., Fecher, G.H., Bansmann, J., Lu, L. & Schönhense, G. k-resolved electronic properties of ternary heavy fermion systems 1998 Physical Review B
    Vol. 58(15), pp. 9670-9673 
    article DOI  
    Abstract: Electronic and structural properties of the heavy fermion intermetallics CePd2Si2 and CeNi2Ge2 were determined using the techniques of low-energy electron diffraction, electron-energy-loss spectroscopy (EELS) and resonant photoemission. Atomically clean and well-ordered surfaces were prepared by evaporating the corresponding crystal onto a W(110) crystal. This preparation procedure allows the application of angle-resolved electron spectroscopic methods being sensitive to surface properties. The behavior of the rare-earth f states was determined by EELS. Resonant photoemission was carried out by tuneable synchrotron radiation allowing a direct assignment of the orbital nature of the electron states hybridizing in the valence band as well as to distinguish between states of the different constituents. [S0163-1829(98)02336-4].
    BibTeX:
    @article{Getzlaff1998a,
      author = {Getzlaff, M. and Schmied, B. and Wilhelm, M. and Kubler, U. and Fecher, G. H. and Bansmann, J. and Lu, L. and Schönhense, G.},
      title = {k-resolved electronic properties of ternary heavy fermion systems},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {1998},
      volume = {58},
      number = {15},
      pages = {9670--9673},
      doi = {http://dx.doi.org/10.1103/PhysRevB.58.9670}
    }
    
    Getzlaff, M. & Schönhense, G. Electronic structure of terpene derivatives 1998 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 95(2-3), pp. 225-230 
    article DOI  
    Abstract: He I photoelectron spectra of terpene derivatives and their preparative intermediates have been measured. The changes of the ionization potentials are discussed in relation to the corresponding variations of the electronic structure. Especially, the effect of methyl and oxygen substitution has been studied. (C) 1998 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Getzlaff1998b,
      author = {Getzlaff, M. and Schönhense, G.},
      title = {Electronic structure of terpene derivatives},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {95},
      number = {2-3},
      pages = {225--230},
      doi = {http://dx.doi.org/10.1016/S0368-2048(98)00212-6}
    }
    
    Kuch, W., Fromter, R., Gilles, J., Hartmann, D., Ziethen, C., Schneider, C.M., Schönhense, G., Swiech, W. & Kirschner, J. Element-selective magnetic imaging in exchange-coupled systems by magnetic photoemission microscopy 1998 Surface Review And Letters
    Vol. 5(6), pp. 1241-1248 
    article DOI  
    Abstract: We have used a photoemission microscope to obtain element-resolved magnetic contrast in stacked magnetic thin film systems. Magnetic information is thereby provided by X-ray magnetic circular dichroism. Elemental sensitivity, which is crucial for studying magnetic coupling phenomena in systems with several different layers, is achieved by tuning the energy of the illuminating photons to atomic absorption edges. We present measurements of a Ni-coated Co micropattern on Cu(001), and a wedged Co/Cr/Fe(001) sample. In the former sample the Ni magnetization is seen to follow the magnetization of the Co pattern, thereby changing from an out-of-plane easy axis in areas without underlying Co to in-plane on top of the Co microstructures. In the latter a reversal of the exchange coupling of the Co layer to the Fe magnetization is observed when the Cr layer thickness exceeds approximately two monolayers. A small net magnetic moment is also observed in the Cr spacer layer, which follows in sign the Co magnetization at the reversal of the exchange coupling. This finding is discussed in terms of interface roughness or interdiffusion.
    BibTeX:
    @article{Kuch1998,
      author = {Kuch, W. and Fromter, R. and Gilles, J. and Hartmann, D. and Ziethen, C. and Schneider, C. M. and Schönhense, G. and Swiech, W. and Kirschner, J.},
      title = {Element-selective magnetic imaging in exchange-coupled systems by magnetic photoemission microscopy},
      journal = {Surface Review And Letters},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {1998},
      volume = {5},
      number = {6},
      pages = {1241--1248},
      doi = {http://dx.doi.org/10.1142/S0218625X98001572}
    }
    
    Schmidt, O., Ziethen, C., Fecher, G.H., Merkel, M., Escher, M., Menke, D., Kleineberg, U., Heinzmann, U. & Schönhense, G. Chemical microanalysis by selected-area ESCA using an electron energy filter in a photoemission microscope 1998 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 88, pp. 1009-1014 
    article DOI  
    Abstract: We present a new and simple device for microspectroscopy being independent of the mode of electron-excitation. Micro-Xray photoelectron spectroscopy, electron-induced Anger-spectroscopy, as well as local energy-loss spectroscopy were used to investigate metal-adsorption on silicon. This new approach employs a non-imaging electron energy analyser attached to a new-generation photoemission electron microscope with integral microarea selector. Photoelectron microspectroscopy was performed using the direct beam of an undulator (U2 at BESSY) being monochromatised and focused by means of multilayer optics at hv = 95 eV. Similarly, local Auger-electron and EELS spectra have been taken using a simple electron gun for the excitation. The chemical compositions of inhomogenities in thin layers of indium on silicon and the local state of oxidation of a structured Pt-Co multilayer have been determined. (C) 1998 Elsevier Science B.V.
    BibTeX:
    @article{Schmidt1998,
      author = {Schmidt, O. and Ziethen, C. and Fecher, G. H. and Merkel, M. and Escher, M. and Menke, D. and Kleineberg, U. and Heinzmann, U. and Schönhense, G.},
      title = {Chemical microanalysis by selected-area ESCA using an electron energy filter in a photoemission microscope},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {88},
      pages = {1009--1014},
      doi = {http://dx.doi.org/10.1016/S0368-2048(97)00279-X}
    }
    
    Schmied, B., Fecher, G.H., Schneider, C.M. & Schönhense, G. Preparation of thin films of the ternary heavy fermion system CeNi2Ge2 1998 Applied Physics A-Materials Science & Processing
    Vol. 66(4), pp. 385-391 
    article DOI  
    Abstract: We investigated the growth, structure, and electronic properties of thin CeNi2Ge2 layers on W(110). In order to produce well-ordered and atomically clean surfaces of the Ce-based intermetallic system the growth was performed under UHV conditions (p < 2 x 10(-11) mbar). Both the polycrystalline CeNi2Ge2 compound and the individual elements Ce, Ni, and Ge were used as evaporants. The characterisation of the layers was made with LEED, SEM, and XPS. We find a significant influence of the substrate temperature and the evaporation power on the growth characteristics. The compound material CeNi2Ge2 exhibits complicated behaviour when evaporated. Under carefully selected growth conditions we obtain well-ordered films with a stoichiometry of Ce:Ni:Ge = 1 : 2 : 2 and a (001) oriented surface of the body-centered tetragonal ThCr2Si2-type structure. The k(parallel to) dispersion and binding energies of the valence bands of these lavers were determined with ARUPS.
    BibTeX:
    @article{Schmied1998,
      author = {Schmied, B. and Fecher, G. H. and Schneider, C. M. and Schönhense, G.},
      title = {Preparation of thin films of the ternary heavy fermion system CeNi2Ge2},
      journal = {Applied Physics A-Materials Science & Processing},
      publisher = {Springer Verlag},
      year = {1998},
      volume = {66},
      number = {4},
      pages = {385--391},
      doi = {http://dx.doi.org/10.1007/s003390050682}
    }
    
    Spiecker, H., Schmidt, O., Ziethen, C., Menke, D., Kleineberg, U., Ahuja, R.C., Merkel, M., Heinzmann, U. & Schönhense, G. Time-of-flight photoelectron emission microscopy TOF-PEEM: first results 1998 Nuclear Instruments & Methods In Physics Research Section A-Accelerators Spectrometers Detectors And Associated Equipment
    Vol. 406(3), pp. 499-506 
    article DOI  
    Abstract: The time structure of the synchrotron radiation at BESSY (Berlin) is used to operate a photoemission electron microscope in a time-of-flight (TOF) mode. The electrons which are emitted from the sample surface with different energies are dispersed in a drift tube subsequent to the imaging optics. The screen of the microscope was replaced by a fast scintillator (tau = 1.4 ns) and the light is detected by an ultra fast gated intensified CCD camera (800 ps gate 1 MHz repetition rate). The resolving power in the energy domain is demonstrated and possible implications on the spatial resolution (chromatic correction) are discussed. Additionally, an improved contrast at very low emission energies is shown. The capability of the setup as an efficient microspectroscopic tool is illustrated. (C) 1998 Elsevier Science B.V. All rights reserved.
    BibTeX:
    @article{Spiecker1998,
      author = {Spiecker, H. and Schmidt, O. and Ziethen, C. and Menke, D. and Kleineberg, U. and Ahuja, R. C. and Merkel, M. and Heinzmann, U. and Schönhense, G.},
      title = {Time-of-flight photoelectron emission microscopy TOF-PEEM: first results},
      journal = {Nuclear Instruments & Methods In Physics Research Section A-Accelerators Spectrometers Detectors And Associated Equipment},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {406},
      number = {3},
      pages = {499--506},
      doi = {http://dx.doi.org/10.1016/S0168-9002(97)01215-1}
    }
    
    Swiech, W., Frömter, R., Schneider, C., Kuch, W., Ziethen, C., Schmidt, O., Fecher, G., Schönhense, G. & Kirschner, J. Magnetically resolved and element specific imaging with photoelectrons using an immersion lens column 1998
    Vol. 2Electron Microscopy 1998, pp. 511 
    incollection  
    BibTeX:
    @incollection{Swiech1998,
      author = {Swiech, W. and Frömter, R. and Schneider, C.M. and Kuch, W. and Ziethen, Ch. and Schmidt, O. and Fecher, G.H. and Schönhense, G. and Kirschner, J.},
      title = {Magnetically resolved and element specific imaging with photoelectrons using an immersion lens column},
      booktitle = {Electron Microscopy 1998},
      publisher = {IOP Bristol and Philadelphia},
      year = {1998},
      volume = {2},
      pages = {511}
    }
    
    Ziethen, C., Schmidt, O., Fecher, G.H., Schneider, C.M., Schönhense, G., Fromter, R., Seider, M., Grzelakowski, K., Merkel, M., Funnemann, D., Swiech, W., Gundlach, H. & Kirschner, J. Fast elemental mapping and magnetic imaging with high lateral resolution using a novel photoemission microscope 1998 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 88, pp. 983-989 
    article DOI  
    Abstract: Using tunable soft X-ray synchrotron radiation and a new-generation photoemission electron microscope with integral sample stage and microarea selector, elemental images and local XANES spectra have been measured. Given the present conditions (PM3 at BESSY), the lateral resolution was in the range of 130 nm with the potential of considerable improvement with high-brilliance sources (a base resolution of 25 nm was obtained in threshold photoemission). Measurements at the oxygen K-edge demonstrate that differences in the local chemical environment of the emitter atom are clearly revealed and can thus be used as a fingerprint technique for its chemical state and geometrical surroundings. By exploiting the magnetic circular dichroism effect it was possible to view magnetic domains and domain walls. (C) 1998 Elsevier Science B.V.
    BibTeX:
    @article{Ziethen1998,
      author = {Ziethen, C. and Schmidt, O. and Fecher, G. H. and Schneider, C. M. and Schönhense, G. and Fromter, R. and Seider, M. and Grzelakowski, K. and Merkel, M. and Funnemann, D. and Swiech, W. and Gundlach, H. and Kirschner, J.},
      title = {Fast elemental mapping and magnetic imaging with high lateral resolution using a novel photoemission microscope},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1998},
      volume = {88},
      pages = {983--989},
      doi = {http://dx.doi.org/10.1016/S0368-2048(97)00265-X}
    }
    
    Fecher, G.H., Grunewald, C., Merkel, M., Ostertag, C., Oelsner, A., Schönhense, G., Jentzsch, T. & Jupner, H.J. Circular dichroism in angular resolved photoemission from pure and Rb-doped C-60 and C22H14 layers on platinum and tungsten 1997 Thin Solid Films
    Vol. 303(1-2), pp. 58-65 
    article DOI  
    Abstract: Polycrystalline C-60 and Pentacene films frown on W(110) and Pt(111) have been studied in valence band photoemission using circularly polarised synchrotron radiation from BESSY with special emphasis on circular dichroism in photoemission. For thin films of C-60, dichroic asymmetries of about 10% occur independent of the temperature and the substrate hinting that the rotation of the topmost layer is hindered even at room temperature. For Pentacene we found asymmetries lip to 50% in the region of the sigma-electrons. Moreover. we found for this molecule a dichroic asymmetry in normal emission, that is a forbidden geometry. This hints on adsorption with the molecules perpendicularly oriented at the surface. Doping the films with rubidium causes a filling of unoccupied electronic states in both molecules. In Pentacene all valence level binding energies are shifted depending on the amount of exposed Rb. For the Rb-doped C-60 and C22H14 films a dichroism in emission from the Rb 4p signal occurs that is much stronger than in the case of pure. disordered Rb films at Pt(111) where the asymmetry almost vanishes. This hints on a high correlation of the Rb p-electrons in both materials that may not be neglected in investigations of the electronic structure. (C) 1997 Elsevier Science S.A.
    BibTeX:
    @article{Fecher1997,
      author = {Fecher, G. H. and Grunewald, C. and Merkel, M. and Ostertag, C. and Oelsner, A. and Schönhense, G. and Jentzsch, T. and Jupner, H. J.},
      title = {Circular dichroism in angular resolved photoemission from pure and Rb-doped C-60 and C22H14 layers on platinum and tungsten},
      journal = {Thin Solid Films},
      publisher = {Elsevier Science Sa Lausanne},
      year = {1997},
      volume = {303},
      number = {1-2},
      pages = {58--65},
      doi = {http://dx.doi.org/10.1016/S0040-6090(97)00088-6}
    }
    
    Getzlaff, M., Bansmann, J., Braun, J. & Schönhense, G. Surface magnetism of iron on W(110) 1997 Zeitschrift Fur Physik B-Condensed Matter
    Vol. 104(1), pp. 11-20 
    article URL 
    Abstract: Ultrathin bcc iron films grown epitaxially on W(110) have been investigated by means of angle and spin resolving photoelectron spectroscopy. The electron spin polarization, spin resolved intensities and corresponding band structure have been experimentally investigated in dependence of the film thickness, exciting photon energy and variation of the photoelectron detection angle. Additionally, photoemission calculations for bulk iron have been performed in the framework of a relativistic one-step formalism. The comparison between measured and calculated spectra turns out to be in very good agreement for different excitation energies as well as for different angles of emission.
    BibTeX:
    @article{Getzlaff1997,
      author = {Getzlaff, M. and Bansmann, J. and Braun, J. and Schönhense, G.},
      title = {Surface magnetism of iron on W(110)},
      journal = {Zeitschrift Fur Physik B-Condensed Matter},
      publisher = {Springer Verlag},
      year = {1997},
      volume = {104},
      number = {1},
      pages = {11--20},
      url = {http://scholar.google.com/scholar?num=30&hl=en&lr=&cluster=3404452398345801619}
    }
    
    Getzlaff, M. & Schönhense, G. Electronic structure of adsorbed organic molecules 1997 Surface Science
    Vol. 377(1-3), pp. 187-191 
    article  
    Abstract: We report on investigations of chiral organic molecules in the gas phase and physisorbed on graphite. The measurements were carried out by means of angle-resolving VUV photoelectron spectroscopy. The emission from specific orbitals in oriented molecules can be forbidden because of dipole selection rules. Due to the lack of certain features in the spectra, it was possible to determine the adsorption geometry of cyclohexanone and camphor as being with their ring system parallel to the surface. By comparison of gasphase and adsorbate spectra of ethyl benzene derivatives, adsorption could be proved to be molecular without decomposition. For amino acids on graphite, the occurrence of characteristic features gives direct evidence for molecular adsorption, despite of their very low vapor pressure in the gas phase.
    BibTeX:
    @article{Getzlaff1997a,
      author = {Getzlaff, M. and Schönhense, G.},
      title = {Electronic structure of adsorbed organic molecules},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {377},
      number = {1-3},
      pages = {187--191}
    }
    
    Marx, G.K.L., Gerheim, V. & Schönhense, G. Multipole WIEN-filter for a high-resolution X-PEEM 1997 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 84(1-3), pp. 251-261 
    article DOI  
    Abstract: The development and construction of an X-PEEM with integral multipole WIEN-filter for spectromicroscopy with high lateral resolution is presented. All relevant electron-optical properties of the filter have been examined by field and trajectory calculations. Electric and magnetic multipole components (dipole, quadrupole and hexapole) can be chosen independently from each other, thus allowing electron-optical corrections. Theoretical values for the lateral resolution are in the range of 10 nm, experimental values of less than or equal to 25 nm have been achieved using the column without filter. The instrument is designed in particular for the use of Sychrotron radiation as well as new, high-brilliance laboratory X-ray sources. (C) 1997 Elsevier Science B.V.
    BibTeX:
    @article{Marx1997,
      author = {Marx, G. K. L. and Gerheim, V. and Schönhense, G.},
      title = {Multipole WIEN-filter for a high-resolution X-PEEM},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {84},
      number = {1-3},
      pages = {251--261},
      doi = {http://dx.doi.org/10.1016/S0368-2048(97)00029-7}
    }
    
    Ostertag, C., Paul, J., Cherepkov, N.A., Oelsner, A., Fecher, G.H. & Schönhense, G. Dichroism in VUV photoemission from the (0001)-surfaces of ultrathin Gd and Nd films on W(110) 1997 Surface Science
    Vol. 377(1-3), pp. 427-431 
    article  
    Abstract: Ultrathin layers of Gd and Nd epitaxially grown on W(110) have been investigated using linearly and circularly polarised light at the 6.5 m NIM beamline at the BESSY storage ring in Berlin. The high quality of the films was monitored by the sharp and dispersionless surface state just below the Fermi energy. The CDAD (circular dichroism in the angular distribution of photoelectrons) measurements showed strong effects in the surface states as well as in the valence bands. The LMDAD (linear magnetic dichroism in...) from Gd(0001) showed a small, but significant splitting of the surface state. This splitting can be reproduced by numerical onestep calculations based on spin-dependent surface barriers. The photon energy-dependent intensities as well as the magnetic dichroism could be explained qualitatively by calculations within an atomic model giving evidence of a Fano-type resonance.
    BibTeX:
    @article{Ostertag1997,
      author = {Ostertag, C. and Paul, J. and Cherepkov, N. A. and Oelsner, A. and Fecher, G. H. and Schönhense, G.},
      title = {Dichroism in VUV photoemission from the (0001)-surfaces of ultrathin Gd and Nd films on W(110)},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {377},
      number = {1-3},
      pages = {427--431}
    }
    
    Schicketanz, M., Oelsner, A., Morais, J., Jentzsch, T., Fecher, G.H. & Schönhense, G. The dependence of circular dichroism in photoemission on the optical properties of Cs monolayers on Pt(111) 1997 Surface Science
    Vol. 377(1-3), pp. 432-435 
    article  
    Abstract: We report on the dependence of dichroic photoemission excited by circularly polarised light on the angle of photon incidence. We measured the difference in the angle-resolved photoemission intensities from Cs 5p semi-core levels excited by photons of opposite helicity, which is known as CDAD. We found that the dependence of the measured differences on the angle of light incidence deviates strongly from the model of CDAD for free atoms, as expected. Using the Fresnel equations and a complex index of refraction, one finds that not only the third component but also the second component of the Stokes vector is responsible for the excitation process. Both Stokes components change sign if the initial helicity is reversed, resulting in an additional linear dichroism.
    BibTeX:
    @article{Schicketanz1997,
      author = {Schicketanz, M. and Oelsner, A. and Morais, J. and Jentzsch, T. and Fecher, G. H. and Schönhense, G.},
      title = {The dependence of circular dichroism in photoemission on the optical properties of Cs monolayers on Pt(111)},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {377},
      number = {1-3},
      pages = {432--435}
    }
    
    Schmied, B., Wilhelm, M., Kubler, U., Getzlaff, M., Fecher, G.H. & Schönhense, G. Electron-spectroscopic investigations on ternary HFS: CeT2X2 1997 Physica B
    Vol. 230, pp. 290-293 
    article DOI  
    Abstract: Investigations of the electronic properties were carried out for ternary Ce-based heavy fermion systems. The well-ordered surfaces of HFS were prepared by MBE on W (110) with subsequent annealing. The layers are characterised by MEED, LEED, AES and XPS. For the electron-spectroscopic investigations, ARUPS and SPEELS were used. In the photoemission spectra, dispersion effects could be detected. By means of SPEELS, the dipole-forbidden Ce f-f transitions could be observed. The comparison of the energy loss spectra above and below the characteristic temperature T* reveals differences in the energy losses as well as in the asymmetries.
    BibTeX:
    @article{Schmied1997,
      author = {Schmied, B. and Wilhelm, M. and Kubler, U. and Getzlaff, M. and Fecher, G. H. and Schönhense, G.},
      title = {Electron-spectroscopic investigations on ternary HFS: CeT2X2},
      journal = {Physica B},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {230},
      pages = {290--293},
      doi = {http://dx.doi.org/10.1016/S0921-4526(96)00685-0}
    }
    
    Schmied, B., Wilhelm, M., Kubler, U., Getzlaff, M., Fecher, G.H. & Schönhense, G. Angular-resolved electron spectroscopy from (110) surfaces of ternary Ce-based intermetallics: CePd2Si2 and CeNi2Ge2 1997 Surface Science
    Vol. 377(1-3), pp. 251-255 
    article  
    Abstract: Investigations of electronic properties were carried out for the ternary Ce-based intermetallic systems CeT2X2 (T = Ni Ed; X = Ge, Si). To produce well-ordered and atomically clean surfaces, preparation is carried out in UHV. The polycrystalline substance was evaporated on a W(110) substrate with subsequent annealing. The single-crystalline layers obtained are characterised by MEED (thickness), AES (surface stoichiometry), LEED and SEM (surface structure). For electron-spectroscopic investigations, ARUPS (angle-resolved photoemission spectroscopy) was used. In the photoemission spectra, dispersion effects could be detected by variation of the detection angle.
    BibTeX:
    @article{Schmied1997a,
      author = {Schmied, B. and Wilhelm, M. and Kubler, U. and Getzlaff, M. and Fecher, G. H. and Schönhense, G.},
      title = {Angular-resolved electron spectroscopy from (110) surfaces of ternary Ce-based intermetallics: CePd2Si2 and CeNi2Ge2},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {377},
      number = {1-3},
      pages = {251--255}
    }
    
    Schmied, B., Wilhelm, M., Kubler, U., Getzlaff, M., Fecher, G.H. & Schönhense, G. Clean and ordered surfaces of CeNi2Ge2 layers on W(110) 1997 Fresenius Journal Of Analytical Chemistry
    Vol. 358(1-2), pp. 141-143 
    article  
    Abstract: Investigations of the geometric and electronic properties of ternary Ce-based heavy fermion systems CeT2X2 (T:Ni,Pd,Rh; X:Ge,Si) were carried out by means of electron spectroscopic methods. The main problem for these surface-sensitive techniques is the preparation of well-ordered and atomically clean surfaces. The ternary substance CeNi2Ge2 was grown on a W(110) substrate by MBE with subsequent annealing. A nearly layer-by-layer growth mode was detected using MEED. The annealed layers are ordered, but show small Ni2Ge crystalline islands. The composition was characterised by means of AES in dependence of the substrate as well as the annealing temperature. Electronic properties are investigated by angle resolved photoelectron spectroscopy.
    BibTeX:
    @article{Schmied1997b,
      author = {Schmied, B. and Wilhelm, M. and Kubler, U. and Getzlaff, M. and Fecher, G. H. and Schönhense, G.},
      title = {Clean and ordered surfaces of CeNi2Ge2 layers on W(110)},
      journal = {Fresenius Journal Of Analytical Chemistry},
      publisher = {Springer Verlag},
      year = {1997},
      volume = {358},
      number = {1-2},
      pages = {141--143}
    }
    
    Schneider, C.M., Fromter, R., Swiech, W., Ziethen, C., Schmidt, O., Fecher, G.H., Schönhense, G. & Kirschner, J. Magnetic spectromicroscopy and microspectroscopy with submicrometer resolution 1997 Journal Of Applied Physics
    Vol. 81(8), pp. 5020-5020 
    article DOI  
    Abstract: Conventional techniques of magnetic domain imaging are usually not selective with respect to the chemical species in a system under investigation. This limitation can be overcome by employing soft x-ray magnetic dichroism which combines both magnetic sensitivity and chemical selectivity. We present first results on magnetic domain imaging at surfaces obtained with a newly developed photoelectron emission microscope using magnetic circular dichroism (MCD). Topographic studies on a silicon surface showed the instrument to be capable of a lateral resolution of better than 50 nm. Two approaches of separating chemical and magnetic information are demonstrated for Permalloy micropatterns on silicon. First, the lateral distribution of the different chemical species or the magnetic domains is obtained by subtracting images taken at different photon energies (spectromicroscopy). Second, a "small spot" mode permits the acquisition of x-ray absorption spectra from surface areas of less than 2 µm diameter. The latter technique is called microspectroscopy. On a Fe(100) whisker surface we observed magnetic domains with domain boundaries ~ 300 nm wide. This value corresponds to the intrinsic width of a 180° domain wall at the surface, as determined by scanning electron microscopy with spin polarization analysis.1 The studies in Ref. 1 have also shown that this kind of domain wall behaves Neél-like at the surface, i.e., the magnetization vector M rotates within the film plane over the domain boundary. Exploiting the directional characteristics of MCD we can map the component of M normal to the domain boundary and thus selectively image the wall itself.
    BibTeX:
    @article{Schneider1997,
      author = {Schneider, C. M. and Fromter, R. and Swiech, W. and Ziethen, C. and Schmidt, O. and Fecher, G. H. and Schönhense, G. and Kirschner, J.},
      title = {Magnetic spectromicroscopy and microspectroscopy with submicrometer resolution},
      journal = {Journal Of Applied Physics},
      publisher = {Amer Inst Physics},
      year = {1997},
      volume = {81},
      number = {8},
      pages = {5020--5020},
      doi = {http://dx.doi.org/10.1063/1.364495}
    }
    
    Swiech, W., Fecher, G.H., Ziethen, C., Schmidt, O., Schönhense, G., Grzelakowski, K., Schneider, C.M., Fromter, R., Oepen, H.P. & Kirschner, J. Recent progress in photoemission microscopy with emphasis on chemical and magnetic sensitivity 1997 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 84(1-3), pp. 171-188 
    article DOI  
    Abstract: With the improved access to synchrotron radiation sources photoemission electron microscopy is developing into a versatile analytical tool in surface and materials science. The broad spectral range and the well-defined polarization characteristics of synchrotron light permit a unique combination of topographic, chemical, and even magnetic investigations down to a mesoscopic scale. The potentiality of photoemission electron microscopy is demonstrated by several experiments on surfaces and microstructured thin film systems, which have been carried out with a newly designed instrument. We discuss its different modes of operation with respect to both microscopy and spectroscopy. A combination of elemental selectivity and magnetic sensitivity is achieved by using circularly polarized soft X-rays and exploiting the effect of magnetic circular dichroism. This way one obtains information about the magnetic state of individual chemical components within the sample. (C) 1997 Elsevier Science B.V.
    BibTeX:
    @article{Swiech1997,
      author = {Swiech, W. and Fecher, G. H. and Ziethen, C. and Schmidt, O. and Schönhense, G. and Grzelakowski, K. and Schneider, C. M. and Fromter, R. and Oepen, H. P. and Kirschner, J.},
      title = {Recent progress in photoemission microscopy with emphasis on chemical and magnetic sensitivity},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1997},
      volume = {84},
      number = {1-3},
      pages = {171--188},
      doi = {http://dx.doi.org/10.1016/S0368-2048(97)00022-4}
    }
    
    Marx, G.K.L., Gerheim, V. & Schönhense, G. Development and production of a Wien filter for a high-resolution emission electron microscope 1997 European Journal Of Cell Biology
    Vol. 74, pp. 6-6 
    article  
    BibTeX:
    @article{,
      author = {Marx, G. K. L. and Gerheim, V. and Schönhense, G.},
      title = {Development and production of a Wien filter for a high-resolution emission electron microscope},
      journal = {European Journal Of Cell Biology},
      publisher = {Wissenschaftliche Verlag Mbh},
      year = {1997},
      volume = {74},
      pages = {6--6}
    }
    
    Marx, G.K.L., von Przychowski, M.D., Klais, M. & Schönhense, G. Possible uses of the emission electron microscope in physical analysis of surfaces 1997 European Journal Of Cell Biology
    Vol. 74, pp. 57-57 
    article  
    BibTeX:
    @article{,
      author = {Marx, G. K. L. and von Przychowski, M. D. and Klais, M. and Schönhense, G.},
      title = {Possible uses of the emission electron microscope in physical analysis of surfaces},
      journal = {European Journal Of Cell Biology},
      publisher = {Wissenschaftliche Verlag Mbh},
      year = {1997},
      volume = {74},
      pages = {57--57}
    }
    
    Bansmann, J., Getzlaff, M., Ostertag, C. & Schönhense, G. Magnetic circular and linear dichroism in VUV-photoemission from thin iron films on W(110) 1996 Surface Science
    Vol. 352, pp. 898-901 
    article  
    Abstract: We report on two different photoemission techniques for ferromagnetic surfaces: the phenomena of magnetic circular and linear dichroism in the angular distribution of photoelectrons MCDAD and MLDAD. MCDAD had already been studied in detail for different systems. Now we are able to compare our MCDAD results from thin iron films on W(110) to new data from magnetic linear dichroism MLDAD. Both effects (MCDAD and MLDAD) have been studied in the identical photon energy region (up to hv = 36 eV). The results will be discussed with respect to a bandstructure calculation.
    BibTeX:
    @article{Bansmann1996,
      author = {Bansmann, J. and Getzlaff, M. and Ostertag, C. and Schönhense, G.},
      title = {Magnetic circular and linear dichroism in VUV-photoemission from thin iron films on W(110)},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1996},
      volume = {352},
      pages = {898--901}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Spin resolved photoemission study of oxygen on thin cobalt films 1996 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 77(2), pp. 197-207 
    article DOI  
    Abstract: Investigations concerning the magnetic interactions and dispersion effects of oxygen adsorbed on thin cobalt films have been carried out by angle and spin resolving photoelectron spectroscopy. Cobalt evaporated on W(110), showing the surface of a h.c.p. (0001) crystal, served as ferromagnetic substrate. Photoelectron spin analysis allows the distinction between chemisorbed oxygen and cobalt oxide in its different oxidation states (antiferromagnetic CoO and Co3O4) at different substrate temperatures. The exchange splittings of the adsorbate derived bands of chemisorbed oxygen are investigated as a function of excitation energy, coverage, temperature, and emission angle. The non-vanishing splittings give evidence for an induced magnetic moment within the adsorbate layer.
    BibTeX:
    @article{Getzlaff1996,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Spin resolved photoemission study of oxygen on thin cobalt films},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1996},
      volume = {77},
      number = {2},
      pages = {197--207},
      doi = {http://dx.doi.org/10.1016/0368-2048(95)02498-0}
    }
    
    Getzlaff, M., Paul, J., Bansmann, J., Ostertag, C., Fecher, G.H. & Schönhense, G. Oxygen adsorbed on rare earth surfaces 1996 Surface Science
    Vol. 352, pp. 123-127 
    article  
    Abstract: The adsorption of oxygen on the surfaces of the rare earth metals Gd, Nd, and Tb was investigated using VUV photoelectron spectroscopy. As substrates served thin films showing the (0001) surfaces of crystals. This study utilized the technique of circular dichroism in the angular distribution of photoelectrons CDAD. The CDAD asymmetry, determined by the normalized difference of the photoelectron intensities for right and left circularly polarized radiation, is reduced with increasing oxygen exposure. The behavior of the asymmetry of the O 2p induced structure is rather similar for oxygen on neodymium and terbium. On gadolinium, in contrast, the observed feature is different including a change of sign. This observation points to different electronic properties of the adsorbate overlayers.
    BibTeX:
    @article{Getzlaff1996a,
      author = {Getzlaff, M. and Paul, J. and Bansmann, J. and Ostertag, C. and Fecher, G. H. and Schönhense, G.},
      title = {Oxygen adsorbed on rare earth surfaces},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1996},
      volume = {352},
      pages = {123--127}
    }
    
    Getzlaff, M., Bansmann, J., Braun, J. & Schönhense, G. Spin resolved photoemission study of Co(0001) films 1996 Journal Of Magnetism And Magnetic Materials
    Vol. 161, pp. 70-88 
    article DOI  
    Abstract: Thin ferromagnetic films are of great practical interest as they can exhibit a different magnetic behaviour compared to the bulk crystals due to, e.g., the surface anisotropy. The electronic and magnetic properties of thin cobalt films evaporated on W(110) have been investigated by means of angle and spin resolving photoelectron spectroscopy, The study was focused on electron spin polarization, spin resolved intensities and band structure behaviour in dependence of film thickness, excitation energy, and photoelectron detection angle. In order to interpret the experimental results, we have performed relativistic band structure calculations for the Co(0001) surface. The observed agreement between experiment and theory turns out to be very satisfactory.
    BibTeX:
    @article{Getzlaff1996b,
      author = {Getzlaff, M. and Bansmann, J. and Braun, J. and Schönhense, G.},
      title = {Spin resolved photoemission study of Co(0001) films},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {1996},
      volume = {161},
      pages = {70--88},
      doi = {http://dx.doi.org/10.1016/S0304-8853(96)00026-1}
    }
    
    Ostertag, C., Oelsner, A., Schicketanz, M., Schmidt, O., Fecher, G.H. & Schönhense, G. Circular dichroism in photoemission from Xe and Kr on Pt(111) 1996 Surface Science
    Vol. 352, pp. 179-183 
    article  
    Abstract: We investigated circular dichroism in photoemission from Kr and Xe adsorbed on Pt(111). A large CDAD has been observed in emission from the p states of both rare gases depending on the observation angle and the photon energy. Special interest was put on the CDAD in emission from the near-threshold region. Strong CDAD was found in constant final state mode spectra for very low kinetic energies of the photoelectrons. Our results show, that in a completed monolayer the Xe 5p states cannot be treated as atom-like.
    BibTeX:
    @article{Ostertag1996,
      author = {Ostertag, C. and Oelsner, A. and Schicketanz, M. and Schmidt, O. and Fecher, G. H. and Schönhense, G.},
      title = {Circular dichroism in photoemission from Xe and Kr on Pt(111)},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1996},
      volume = {352},
      pages = {179--183}
    }
    
    Schönhense, G. & Hormes, J. Photoionization of Oriented Systems and Circular Dichroism 1996 VUV and Soft X-Ray Photoionization (Physics of Atoms and Molecules), pp. 607-652  incollection URL 
    BibTeX:
    @incollection{Schoenhense1996,
      author = {Schönhense, G. and Hormes, J.},
      title = {Photoionization of Oriented Systems and Circular Dichroism},
      booktitle = {VUV and Soft X-Ray Photoionization (Physics of Atoms and Molecules)},
      publisher = {Kluwer Academic / Plenum Publishers},
      year = {1996},
      pages = {607--652},
      edition = {1},
      url = {http://books.google.com/books?hl=en&lr=&id=m9chfY8jtxYC&oi=fnd&pg=PA1&dq=VUV+and+Soft+X-Ray+Photoionization+&ots=1x4DUnlF5j&sig=bedg39vsX2m4-rdDTXSYgDjFTJM}
    }
    
    Bansmann, J., Ostertag, C., Getzlaff, M., Schönhense, G., Cherepkov, N.A., Kuznetsov, V.V. & Pavlychev, A.A. Circular dichroism in X-ray photoemission from Pd(111) and CO/Pd(111) 1995 Zeitschrift für Physik D: Atoms, Molecules And Clusters
    Vol. 33(4), pp. 257-264 
    article DOI  
    Abstract: It is shown experimentally that in the soft X-ray region a large circular dichroism in the photoelectron angular distribution (CDAD) exists for both valence orbitals and core levels of CO molecules adsorbed on Pd(111). From theoretical consideration it follows that in the case of a spherically symmetric ground state wave function, like the 1sigma and 2sigma orbitals of CO, CDAD appears due to the lack of spherical symmetry in the final state. For carbon K-shell experimental results are compared to model calculations. Investigations at the Pd core levels proved that CDAD does also arise in X-ray photoemission from non-magnetic crystals.
    BibTeX:
    @article{Bansmann1995,
      author = {Bansmann, J. and Ostertag, C. and Getzlaff, M. and Schönhense, G. and Cherepkov, N. A. and Kuznetsov, V. V. and Pavlychev, A. A.},
      title = {Circular dichroism in X-ray photoemission from Pd(111) and CO/Pd(111)},
      journal = {Zeitschrift für Physik D: Atoms, Molecules And Clusters},
      publisher = {Springer},
      year = {1995},
      volume = {33},
      number = {4},
      pages = {257--264},
      doi = {http://dx.doi.org/10.1007/BF01437506}
    }
    
    Bansmann, J., Getzlaff, M. & Schönhense, G. Photoemission from Co/W(110) with unpolarized und circularly polarized radiation 1995 Journal Of Magnetism And Magnetic Materials
    Vol. 148(1-2), pp. 60-61 
    article  
    Abstract: We report on investigations of thin cobalt films evaporated on W(110). The measurements have probed Magnetic Circular Dichroism in photoelectron angular distribution (MCDAD) and spin-resolved photoemission (SPUPS) with unpolarized light. In particular the energetic dependence of the MCDAD-effect and of the spin-resolved intensities were studied. The results of both experiments are compared in order to get a deeper insight into exchange and spin-orbit interactions.
    BibTeX:
    @article{Bansmann1995a,
      author = {Bansmann, J. and Getzlaff, M. and Schönhense, G.},
      title = {Photoemission from Co/W(110) with unpolarized und circularly polarized radiation},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {1995},
      volume = {148},
      number = {1-2},
      pages = {60--61}
    }
    
    Fecher, G.H., Oelsner, A., Ostertag, C. & Schönhense, G. Investigation of alkali metals and noble gases adsorbed on transition metals using circular dichroism in angular resolved photoemission 1995 Journal Of Electron Spectroscopy And Related Phenomena
    Vol. 76, pp. 289-294 
    article DOI  
    Abstract: We investigated the adsorption of alkali metals an noble gases on transition metal surfaces. These serve as atom-like adsorbates to be comparable to calculations of the Circular Dichroism in the Angular Distribution of photoelectrons (CDAD) including backscattering at the substrate surface and photoelectron diffraction within the adsorbate layer. Our calculations show the influence of scattering and diffraction, that even can generate a dichroism where none should be. For the case of the 4p(1,2)-subshell of Rb our calculations agree well with our measurements. For the 4p(3/2)-subshell we found a different behaviour due to a polarisation of the state in the adsorbed layer. We also present first results for CDAD from noble gases. The 5p - states from Xe show less atomic-like behaviour, because they are much more weakly bound and form bands.
    BibTeX:
    @article{Fecher1995,
      author = {Fecher, G. H. and Oelsner, A. and Ostertag, Ch. and Schönhense, G.},
      title = {Investigation of alkali metals and noble gases adsorbed on transition metals using circular dichroism in angular resolved photoemission},
      journal = {Journal Of Electron Spectroscopy And Related Phenomena},
      publisher = {Elsevier Science Bv},
      year = {1995},
      volume = {76},
      pages = {289--294},
      doi = {http://dx.doi.org/10.1016/0368-2048(95)02470-0}
    }
    
    Fecher, G.H., Oelsner, A., Ostertag, C. & Schonhense, G. Enhancement of circular dichroism in photoemission from adsorbates by photoelectron diffraction 1995 Journal of Electron Spectroscopy and Related Phenomena
    Vol. 76, pp. 97-102 
    article DOI  
    Abstract: The presence of the surface causes circular dichroic effects in angular resolved photoemission (CDAD) from electronic states of adsorbates with a spherical symmetric charge distribution. A simple reflection mechanism is introduced to the atomic theory of the angular resolved photoemission from adsorbates excited by polarised light. This model is further refined by including electron diffraction. From both models it is found that interferences of partial waves of the same orbital quantum number cause a new class of CDAD effects. The interference is due to the difference in the path length of the direct and the reflected wave and to the scattering phaseshift. In comparison to experiments from NO adsorbed at Pt(111) it is shown that the CDAD provides to distinguish between different adsorbate geometries.
    BibTeX:
    @article{Fecher1995a,
      author = {Fecher, G. H. and Oelsner, A. and Ostertag, Ch. and Schonhense, G.},
      title = {Enhancement of circular dichroism in photoemission from adsorbates by photoelectron diffraction},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      year = {1995},
      volume = {76},
      pages = {97--102},
      doi = {http://dx.doi.org/10.1016/0368-2048(95)02515-4}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. The electronic structure of benzene adsorbed on thin Fe(110) and Co(0001)films 1995 Surface Science
    Vol. 323(1-2), pp. 118-128 
    article DOI  
    Abstract: Electronic and magnetic properties of condensed and chemisorbed benzene layers on cobalt(0001) and iron(110) surfaces have been determined by means of angle and spin resolving photoelectron spectroscopy. The ferromagnetic substrate was produced by evaporating iron and cobalt films on a W(110) crystal. Condensed benzene layers show a similar behavior as on other densely packed transition metal surfaces. Benzene chemisorbed on Fe/W(110) and Co/W(110) gives evidence for a molecular adsorption and no large differences of its electronic properties. A flat adsorption geometry of the ring and a C-3V symmetry could be demonstrated. Exchange splittings were observed neither for sigma orbitals nor for the sigma orbitals being responsible for the interaction between adsorbate and substrate.
    BibTeX:
    @article{Getzlaff1995,
      author = {Getzlaff , M. and Bansmann, J. and Schönhense , G.},
      title = {The electronic structure of benzene adsorbed on thin Fe(110) and Co(0001)films},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1995},
      volume = {323},
      number = {1-2},
      pages = {118--128},
      doi = {http://dx.doi.org/10.1016/0039-6028(94)00641-5}
    }
    
    Getzlaff, M. & Schönhense, G. Magnetic exchange effects of adsorbates on thin Fe(110) films 1995 Surface Science
    Vol. 333, pp. 213-218 
    article  
    Abstract: An angle and spin resolved photoemission study with very different species on iron is presented. It was carried out with iodine, benzene, and xenon on thin magnetized Fe(110) films grown layer-by-layer on W(110) by molecular beam epitaxy. For atomically adsorbed iodine a strong hybridization occurs, leading to exchange split I 5p(x) and 5p(z) bands reflecting an induced magnetic moment of the iodine overlayer. The molecular adsorbate benzene shows no exchange splittings neither for the sigma nor for the pi orbitals being involved into the bonding to the substrate thus indicating a weaker hybridization between adsorbate and substrate bands. For physisorbed xenon, however, spin splittings occur for both 5p levels due to a nonvanishing net magnetic moment of the ionic hole states leading to a magnetic coupling between substrate and adsorbate ion.
    BibTeX:
    @article{Getzlaff1995a,
      author = {Getzlaff, M. and Schönhense, G.},
      title = {Magnetic exchange effects of adsorbates on thin Fe(110) films},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1995},
      volume = {333},
      pages = {213--218}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Adsorbates on thin iron (100) films 1995 Fresenius Journal Of Analytical Chemistry
    Vol. 353(5-8), pp. 748-752 
    article DOI  
    Abstract: The electronic and magnetic properties of different kinds of adsorbates on thin magnetized Fe(100) films have been investigated by means of spin resolving photoelectron spectroscopy. The study has been carried out with atomically physisorbed xenon, the molecule carbon monoxide, and metallic gold. The spin splitting of the Xe 5p signal can be explained by magnetic interactions with the final ionic hole state. By spin analysis, it could be shown that at room temperature for low exposures the adsorption of CO is dissociative and with increasing exposure additionally molecular. The Au related features for the monolayer show different line shapes in both spin channels but no splittings due to an sp-like behavior of this interface state being dominated by minority character.
    BibTeX:
    @article{Getzlaff1995b,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Adsorbates on thin iron (100) films},
      journal = {Fresenius Journal Of Analytical Chemistry},
      publisher = {Springer Verlag},
      year = {1995},
      volume = {353},
      number = {5-8},
      pages = {748--752},
      doi = {http://dx.doi.org/10.1007/BF00321362}
    }
    
    Getzlaff, M., Cherepkov, N.A. & Schönhense, G. Xenon on ferromagnetic surfaces - a spin resolved photoemission study 1995 Physical Review B
    Vol. 52(5), pp. 3421-3428 
    article DOI  
    Abstract: Physisorbed xenon on magnetized iron (110), iron (100), and cobalt (0001) films has been investigated by means of spin- and angle-resolved photoelectron spectroscopy with unpolarized light. Spin-resolved spectra revealed different energy positions of the 5p(3/2) and 5p(1/2) adsorbate levels in the majority and minority spin channels. The splitting shows a significant angle dependence including a sign reversal, with the maximum occurring in normal emission. This behavior can be qualitatively explained by a spin-dependent pinning of adsorbate and substrate bands.
    BibTeX:
    @article{Getzlaff1995c,
      author = {Getzlaff, M. and Cherepkov, N. A. and Schönhense, G.},
      title = {Xenon on ferromagnetic surfaces - a spin resolved photoemission study},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {1995},
      volume = {52},
      number = {5},
      pages = {3421--3428},
      doi = {http://dx.doi.org/10.1103/PhysRevB.52.3421}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. CO interactions with ferromagnetic surfaces 1995 Journal Of Chemical Physics
    Vol. 103(15), pp. 6691-6696 
    article DOI  
    Abstract: Electronic and magnetic interactions of carbon monoxide with different ferromagnetic substrates (amorphous materials, crystals, and thin films) are investigated by means of angle and spin resolving photoelectron spectroscopy. On none of these surfaces, an exchange splitting of the CO orbitals is present indicating only a weak magnetic interaction of the substrate d bands with the occupied molecular orbitals. Via the spin analysis, a differentiation between molecular adsorption and dissociation was possible. (C) 1995 American Institute of Physics.
    BibTeX:
    @article{Getzlaff1995d,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {CO interactions with ferromagnetic surfaces},
      journal = {Journal Of Chemical Physics},
      publisher = {Amer Inst Physics},
      year = {1995},
      volume = {103},
      number = {15},
      pages = {6691--6696},
      doi = {http://dx.doi.org/10.1063/1.470399}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. A study of the oxidation states of Co(0001) 1995 Journal Of Magnetism And Magnetic Materials
    Vol. 140, pp. 729-730 
    article DOI  
    Abstract: Investigations concerning the magnetic interactions of oxygen with thin cobalt films evaporated on W(110) were carried out by spin resolving photoelectron spectroscopy. In particular, modifications of surface magnetism depending on the chemical state were determined. The formation of different oxidation states at various substrate temperatures could be demonstrated. At room temperature a coexistence of chemisorbed oxygen and antiferromagnetic CoO near the surface was found. With increasing exposure a reduction of the exchange splittings of the oxygen derived bands can be observed for different excitation energies. At low temperatures the formation to Co3O4 starts immediately after dosing oxygen to the cobalt surface.
    BibTeX:
    @article{Getzlaff1995e,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {A study of the oxidation states of Co(0001)},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {1995},
      volume = {140},
      pages = {729--730},
      doi = {http://dx.doi.org/10.1016/0304-8853(94)01609-7}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Photoemission from Fe/W(110) 1995 J. Magn. Magn. Mater.
    Vol. 140-144, pp. 669 
    article DOI  
    Abstract: Thin magnetized Fe/W(110) films were investigated by spin resolving photoelectron spectroscopy with unpolarized VUV-light as well as by magnetic circular dichroism in photoemission using left and right circularly polarized synchrotron radiation. The spin resolved intensities and polarization curve directly reflect the majority and minority spin character of the valence bands along the Σ direction. In contrast, the asymmetry in the photoelectron intensities depending on the helicity of the incoming synchrotron radiation is caused by spin-orbit in combination with exchange interaction. By determination of the spin polarization of photoelectrons and the magnetic circular dichroism one can, in principle, obtain complementary information about the electronic and magnetic properties of the iron film.
    BibTeX:
    @article{Getzlaff1995f,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Photoemission from Fe/W(110)},
      journal = {J. Magn. Magn. Mater.},
      year = {1995},
      volume = {140-144},
      pages = {669},
      doi = {http://dx.doi.org/10.1016/0304-8853(94)01569-4}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Oxygen on Fe(100) and Fe(110) 1995 Fresenius J. Anal. Chem.
    Vol. 353, pp. 743 
    article DOI  
    BibTeX:
    @article{Getzlaff1995g,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Oxygen on Fe(100) and Fe(110)},
      journal = {Fresenius J. Anal. Chem.},
      year = {1995},
      volume = {353},
      pages = {743},
      doi = {http://dx.doi.org/10.1007/BF00321362}
    }
    
    Oelsner, A., Fecher, G.H., Ostertag, C., Jentzsch, T. & Schonhense, G. Dichroic effects in photoemission from pure and oxidised rubidium and potassium monolayers on platinum (111) 1995 Surface Science
    Vol. 331-333(Part 1)Proceedings of the 14th European Conference on Surface Science, pp. 349-354 
    article DOI  
    Abstract: Well-ordered monolayers of rubidium and potassium on platinum Pt(111) have been studied by LEED, angular resolved UPS and XPS excited by circularly polarised synchrotron radiation from the electron storage ring BESSY (Berlin). The order of pure and oxidised monolayers at T = 300 K was investigated by LEED. CDAD has been measured for the Rb 3d, Rb 4p and K 3p states in the case of the ([square root]3 x [square root]3)R30[degree sign] structures of pure Rb and K. Exposure of oxygen to the alkali monolayers leads to disordered alkali oxide layers. After additional heat treatment ordered structures are observed again. In all cases of ordered monolayers CDAD asymmetries up to 30% are found. This is surprising, because the observed initial states have spherical symmetry in particular, at least the p1/2 state. We explain these results by photoelectron diffraction, including neighbouring adsorbate (Rb, K) and underlying substrate (Pt) atoms. Variations of the CDAD asymmetry between 0% and 30% are found to be dependent on the kinetic energy of the photoelectrons up to 190 eV and the angle of observation, respectively.
    BibTeX:
    @article{Oelsner1995,
      author = {Oelsner, A. and Fecher, G. H. and Ostertag, Ch. and Jentzsch, Th. and Schonhense, G.},
      title = {Dichroic effects in photoemission from pure and oxidised rubidium and potassium monolayers on platinum (111)},
      booktitle = {Proceedings of the 14th European Conference on Surface Science},
      journal = {Surface Science},
      year = {1995},
      volume = {331-333},
      number = {Part 1},
      pages = {349--354},
      doi = {http://dx.doi.org/10.1016/0039-6028(95)00334-7}
    }
    
    Ostertag, C., Bansmann, J., Grunewald, C., Jentzsch, T., Oelsner, A., Fecher, G.H. & Schonhense, G. The influence of a linear photon polarisation on measurements of the circular dichroism in photoemission 1995 Surface Science
    Vol. 331-333(Part 2)Proceedings of the 14th European Conference on Surface Science, pp. 1197-1202 
    article DOI  
    Abstract: We measured the CDAD from NO on Pt(111) at the SX/700-III monochromator at the synchrotron BESSY in Berlin. We found high asymmetries up to 60% using a photon energy of 40 eV. Surprisingly, this is higher than the degree of circular polarisation that should be between 30% and 50% for the experimental parameters used. This obvious contradiction can be explained if an additional dichroism arising from a strongly linear polarised component of the radiation at the SX/700-III is taken into account. The polarisation of this component has the orientation of +/-45[degree sign] with respect to the synchrotron plane. This linear polarisation changes its sign if the circular polarisation is changed, too. First experiments on this linear dichroism show large asymmetries for CO/Pt(111), comparable to the CDAD asymmetries.
    BibTeX:
    @article{Ostertag1995,
      author = {Ostertag, Ch. and Bansmann, J. and Grunewald, Ch. and Jentzsch, Th. and Oelsner, A. and Fecher, G. H. and Schonhense, G.},
      title = {The influence of a linear photon polarisation on measurements of the circular dichroism in photoemission},
      booktitle = {Proceedings of the 14th European Conference on Surface Science},
      journal = {Surface Science},
      year = {1995},
      volume = {331-333},
      number = {Part 2},
      pages = {1197--1202},
      doi = {http://dx.doi.org/10.1016/0039-6028(95)00142-5}
    }
    
    Fecher, G.H., Bansmann, J., Grünewald, C., Oelsner, A., Ostertag, C. & Schönhense, G. Oxidation of rubidium at platinum (111) 1994 Surface Science
    Vol. 309, pp. 70-75 
    article  
    Abstract: We have studied the adsorption of Rb and the co-adsorption of 02 and Rb at Pt(111) using LEED, AES, EELS, ARUPS excited by circularly polarised light (CDAD) and workfunction measurements. At T = 300 K different ordered structures occur as indicated by LEED. The pure Rb monolayer exhibits a (7 x 7) structure. Even at very low oxygen exposure ( < 0.05 L) this structure is changed to a (square-root 3 x square-root 3)R30-degrees structure with the same lattice spacing within 1 %. At high oxygen doses the adlayer becomes disordered. A (4 x 1) structure is observed after an additional heat treatment. Simultaneously, different stages of local order can be distinguished clearly by use of CDAD from the Rb 4p states. At T = 90 K disordered Rb adlayers were produced that show an almost vanishing CDAD. For high Rb coverage EELS and DELTAPHI measurements indicate that the suboxide Rb9O2 occurs during the early stage of oxidation.
    BibTeX:
    @article{Fecher1994,
      author = {Fecher, G. H. and Bansmann, J. and Grünewald, Ch. and Oelsner, A. and Ostertag, Ch. and Schönhense, G.},
      title = {Oxidation of rubidium at platinum (111)},
      journal = {Surface Science},
      publisher = {Elsevier Science Bv},
      year = {1994},
      volume = {309},
      pages = {70--75}
    }
    
    Gerheim, V., Marx, G. & Schönhense, G. The possibilities of a multipole Wien filter built in an emission electron microscope 1994
    Vol. 1Electron Microscopy 1994, pp. 251 
    incollection  
    BibTeX:
    @incollection{Gerheim1994,
      author = {Gerheim, V. and Marx, G. and Schönhense, G.},
      title = {The possibilities of a multipole Wien filter built in an emission electron microscope},
      booktitle = {Electron Microscopy 1994},
      publisher = {Les Editions de Physique, Les Ulis},
      year = {1994},
      volume = {1},
      pages = {251}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Magnetic-Interactions In Different Oxidation-States Of Thin Cobalt Films 1994 Journal Of Magnetism And Magnetic Materials
    Vol. 131(3), pp. 304-310 
    article DOI  
    Abstract: Investigations concerning the magnetic interactions of oxygen with thin cobalt films evaporated on W(110) were carried out by spin-resolved photoelectron spectroscopy; in particular modifications of surface magnetism depending on the chemical state were determined. The formation of different oxidation states at various substrate temperatures and the coexistence of chemisorbed oxygen and antiferromagnetic CoO near the surface could be impressively demonstrated. The measurements indicate 'magnetically live' adsorbate layers at the surface revealing an induced magnetic moment of the chemisorbed oxygen atoms.
    BibTeX:
    @article{Getzlaff1994,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Magnetic-Interactions In Different Oxidation-States Of Thin Cobalt Films},
      journal = {Journal Of Magnetism And Magnetic Materials},
      publisher = {Elsevier Science Bv},
      year = {1994},
      volume = {131},
      number = {3},
      pages = {304--310},
      doi = {http://dx.doi.org/10.1016/0304-8853(94)90273-9}
    }
    
    Getzlaff, M., Ostertag, C., Fecher, G.H., Cherepkov, N.A. & Schönhense, G. Magnetic Dichroism In Photoemission With Unpolarized Light 1994 Physical Review Letters
    Vol. 73(22), pp. 3030-3033 
    article DOI  
    Abstract: A magnetic dichroism in photoemission from ferromagnets induced by unpolarized light is observed for the first time in the valence band region as well as for surface states. The study was carried out with magnetized Fe(110), Co(0001), and Gd(0001) films grown epitaxially on W(110). This phenomenon leads to an intensity asymmetry for opposite directions of the sample magnetization. It can be easily used for a routine laboratory diagnostic of magnetic behavior. A simple theoretical interpretation of the phenomenon based on the atomic model is given.
    BibTeX:
    @article{Getzlaff1994a,
      author = {Getzlaff, M. and Ostertag, Ch. and Fecher, G. H. and Cherepkov, N. A. and Schönhense, G.},
      title = {Magnetic Dichroism In Photoemission With Unpolarized Light},
      journal = {Physical Review Letters},
      publisher = {American Physical Soc},
      year = {1994},
      volume = {73},
      number = {22},
      pages = {3030--3033},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.73.3030}
    }
    
    Marx, G.K.L., v. Przychowski, M.D., Krömker, B., Ziethen, C. & Schönhense, G. Construction of a UHV Emission Electron Microscope with Preparation Chamber 1994
    Vol. 1Electron Microscopy 1994, pp. 239 
    incollection  
    BibTeX:
    @incollection{Marx1994,
      author = {Marx, G. K. L. and v. Przychowski, M. D. and Krömker, B and Ziethen, Ch. and Schönhense, G.},
      title = {Construction of a UHV Emission Electron Microscope with Preparation Chamber},
      booktitle = {Electron Microscopy 1994},
      publisher = {Les Editions de Physique, Les Ulis},
      year = {1994},
      volume = {1},
      pages = {239}
    }
    
    Westphal, C., Fegel, F., Bansmann, J., Getzlaff, M., Schönhense, G., Stephens, J.A. & McKoy, V. Orientation And Substrate Interaction Of Adsorbed Co And No Molecules Probed By Circular-Dichroism In The Angular-Distribution Of Photoelectrons 1994 Physical Review B
    Vol. 50(23), pp. 17534-17539 
    article DOI  
    Abstract: The sensitivity and utility of circular dichroism in the angular distribution of photoelectrons (CDAD) as a probe of molecular orientation is demonstrated for adsorbed CO and NO molecules. A comparison between measured CDAD spectra and calculated values for spatially oriented CO and NiCO clearly confirms the well-known perpendicular adsorption for CO on Ni(100), whereas for CO adsorbed on Fe(100) a tilted adsorption geometry was found. For NO/Ni(100) and for NO on the oxygen-preadsorbed Ni(100) surface, an average tilt angle of α=40±10° was observed. In the case of the oxygen-preadsorbed Ni(100) surface, a higher fraction of NO molecules was found to be in a tilted orientation than on the clean surface.
    BibTeX:
    @article{Westphal1994,
      author = {Westphal, C. and Fegel, F. and Bansmann, J. and Getzlaff, M. and Schönhense, G. and Stephens, J. A. and McKoy, V.},
      title = {Orientation And Substrate Interaction Of Adsorbed Co And No Molecules Probed By Circular-Dichroism In The Angular-Distribution Of Photoelectrons},
      journal = {Physical Review B},
      publisher = {American Physical Soc},
      year = {1994},
      volume = {50},
      number = {23},
      pages = {17534--17539},
      doi = {http://dx.doi.org/10.1103/PhysRevB.50.17534}
    }
    
    Cherepkov, N.A. & Schönhense, G. Linear Dichroism in Photoemission from Oriented Molecules 1993 Europhysics Letters
    Vol. 24(2), pp. 79-85 
    article DOI  
    Abstract: It is shown that oriented molecules reveal both Linear Dichroism (LD) and Linear Dichroism in the Angular Distribution (LDAD) of photoelectrons, which means a difference between photoelectron currents ejected at a definite angle by linearly polarized light of two mutually perpendicular polarizations. Measurements of LD and LDAD enable one to investigate the orientation of molecules and to make an essential step towards the complete quantummechanical experiment. As an example, LDAD in a model case of oriented heteronuclear diatomic molecules is presented.
    BibTeX:
    @article{Cherepkov1993,
      author = {Cherepkov, N. A. and Schönhense, G.},
      title = {Linear Dichroism in Photoemission from Oriented Molecules},
      journal = {Europhysics Letters},
      year = {1993},
      volume = {24},
      number = {2},
      pages = {79--85},
      doi = {http://dx.doi.org/10.1209/0295-5075/24/2/001}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Spin-polarization effects for electrons passing through thin iron and cobalt films 1993 Solid State Communications
    Vol. 87(5), pp. 467-469 
    article DOI  
    Abstract: Spin-dependent effects of the inelastic mean free path (IMFP) are evident for low-energy electrons passing through magnetized ferromagnetic films caused by a different attenuation within the layer. Values of IMFP for both spin components were determined for ultrathin iron and cobalt layers on W(1 1 0) by means of spin-resolving photoelectron spectroscopy.
    BibTeX:
    @article{Getzlaff1993,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Spin-polarization effects for electrons passing through thin iron and cobalt films},
      journal = {Solid State Communications},
      year = {1993},
      volume = {87},
      number = {5},
      pages = {467--469},
      doi = {http://dx.doi.org/10.1016/0038-1098(93)90799-S}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Iodine on a magnetized iron film evidence for a magnetic coupling 1993 Physics Letters A
    Vol. 182(1), pp. 153-156 
    article DOI  
    Abstract: Spin-resolved photoelectron spectra of iodine chemisorbed on a magnetized iron (110) surface have been taken using unpolarized VUV light. The partial spin spectra reveal the I 5px and 5pz signals being split by up to 0.35 eV. This exchange splitting occurs due to hybridization of adsorbate and substrate bands as a consequence of the chemical bond of the halogen atoms to the iron surface.
    BibTeX:
    @article{Getzlaff1993a,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Iodine on a magnetized iron film evidence for a magnetic coupling},
      journal = {Physics Letters A},
      year = {1993},
      volume = {182},
      number = {1},
      pages = {153--156},
      doi = {http://dx.doi.org/10.1016/0375-9601(93)90070-G}
    }
    
    Getzlaff, M., Bansmann, J. & Schönhense, G. Spin-resolved photoemission from physisorbed xenon on ferromagnetic surfaces: Evidence for magnetic interactions 1993 Phys. Rev. Lett.
    Vol. 71(5), pp. 793-796 
    article DOI  
    Abstract: Spin-resolved photoelectron spectra of a monolayer of xenon atoms physisorbed on magnetized Fe(110) and Co(0001) surfaces have been taken using unpolarized VUV light. The spin-resolved spectra reveal the Xe 5p signal being split by up to 0.24 eV. This spin splitting can be explained by magnetic adsorbate-substrate interactions which have previously been observed only for strongly chemisorbed species. The results indicate physisorbed rare-gas atoms acting as a kind of ‘‘atomic probe’’ for local surface magnetism.
    BibTeX:
    @article{Getzlaff1993b,
      author = {Getzlaff, M. and Bansmann, J. and Schönhense, G.},
      title = {Spin-resolved photoemission from physisorbed xenon on ferromagnetic surfaces: Evidence for magnetic interactions},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1993},
      volume = {71},
      number = {5},
      pages = {793--796},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.71.793}
    }
    
    Marx, G., von Przychowski, M., Grahneis, W. & Schönhense, G. Bericht über den Aufbau des Mainzer Emissionselektronenmikroskopes 1993 Optik
    Vol. 94(Suppl. 5), pp. 135 
    article  
    BibTeX:
    @article{Marx1993,
      author = {Marx, G. and von Przychowski, M.D. and Grahneis, W. and Schönhense, G.},
      title = {Bericht über den Aufbau des Mainzer Emissionselektronenmikroskopes},
      journal = {Optik},
      year = {1993},
      volume = {94},
      number = {Suppl. 5},
      pages = {135}
    }
    
    Schönhense, G. & Siegmann, H.C. Transmission of electrons through ferromagnetic material and applications to detection of electron spin polarization 1993 Annalen der Physik
    Vol. 505(5), pp. 465-474 
    article DOI  
    Abstract: The salient features of the total low energy inelastic electron scattering cross section in transition metals are described by a constant term 0 plus a term d that is proportional to the number of unoccupied d-orbitals. This simple model predicts that low energy electrons transmitted through a ferromagnetic ultrathin film acquire a transport spin polarization a(). Using the ratio 0/d as the only adjustable parameter, the model predicts the enhancement of the spin polarization of the low energy cascade electrons as well as a() in reasonable agreement with the existing observations on Fe, Co and Ni. A detector for electron spin polarization P based on the spin dependent transmission of electrons through ferromagnetic material is proposed which should be superior to existing P-detectors by 1-2 orders of magnitude.
    BibTeX:
    @article{Schoenhense1993,
      author = {Schönhense, G. and Siegmann, H.~C.},
      title = {Transmission of electrons through ferromagnetic material and applications to detection of electron spin polarization},
      journal = {Annalen der Physik},
      year = {1993},
      volume = {505},
      number = {5},
      pages = {465-474},
      doi = {http://dx.doi.org/10.1002/andp.19935050504}
    }
    
    Bansmann, J., Getzlaff, M., Westphal, C. & Schönhense, G. Surface hysteresis curves of Fe(110) and Fe(100) crystals in ultrahigh vacuum -- evidence of adsorbate influences 1992 Journal of Magnetism and Magnetic Materials
    Vol. 117(1-2), pp. 38-44 
    article DOI  
    Abstract: We have investigated hysteresis curves of silicon-stabilized Fe(100) and Fe(110) crystals using Polarized Secondary Electron Emission (PSEE) for surface magnetization processes and Magneto-Optical Kerr Effect (MOKE) for bulk hysteresis curves. In particular, the influence of adsorbates (oxygen and sulphur) and surface roughness on the magnetization reversal has been studied. For surface hysteresis curves we found adsorbate-induced reductions of coercive force of up to 50%; the bulk hysteresis curves showed significantly smaller deviations. Similar changes were caused by surface disorder on an atomic scale induced by ion bombardment. The results agree qualitatively with a previous experiment on Ni(110).
    BibTeX:
    @article{Bansmann1992,
      author = {Bansmann, J. and Getzlaff, M. and Westphal, C. and Schönhense, G.},
      title = {Surface hysteresis curves of Fe(110) and Fe(100) crystals in ultrahigh vacuum -- evidence of adsorbate influences},
      journal = {Journal of Magnetism and Magnetic Materials},
      year = {1992},
      volume = {117},
      number = {1-2},
      pages = {38--44},
      doi = {http://dx.doi.org/10.1016/0304-8853(92)90289-Z}
    }
    
    Bansmann, J., Getzlaff, M., Westphal, C., Fegel, F. & Schönhense, G. Magnetic circular dichroism in valence-band photoemission from iron (100) 1992 Surface Science
    Vol. 269-270, pp. 622-626 
    article DOI  
    Abstract: We report on a new effect observed in photoemission using circularly polarized synchrotron radiation from BESSY. This phenomenon called magnetic circular dichroism in the angular distribution of photoelectrons (MCDAD) was studied in valence-band photoemission from Fe(100). The photoelectron intensity spectra depend on the helicity of the incoming photon beam. CDAD-effects had been observed for single crystals like Pd(111) and Cu(110), but unlike to these non-magnetic species, we found the MCDAD-signal from Fe(100) reversing when the macroscopic magnetization was reversed. This behavior is caused by exchange splitting in the presence of spin-orbit interaction.
    BibTeX:
    @article{Bansmann1992a,
      author = {Bansmann, J. and Getzlaff, M. and Westphal, C. and Fegel, F. and Schönhense, G.},
      title = {Magnetic circular dichroism in valence-band photoemission from iron (100)},
      journal = {Surface Science},
      year = {1992},
      volume = {269-270},
      pages = {622--626},
      doi = {http://dx.doi.org/10.1016/0039-6028(92)91321-2}
    }
    
    Bansmann, J., Westphal, C., Getzlaff, M., Fegel, F. & Schönhense, G. Magnetic circular dichroism in valence-band photo-emission from Fe(100) 1992 Journal of Magnetism and Magnetic Materials
    Vol. 104-107(Part 3), pp. 1691-1692 
    article DOI  
    Abstract: We report on a new effect in photo-emission with circularly polarized light called Magnetic Circular Dichroism in the Angular Distribution of photo-electrons (MCDAD). The phenomenon was studied in valence-band photo-emission from Fe(100) using synchrotron radiation from the storage ring BESSY (Berlin). In contrast to CDAD with nonmagnetic solids and adsorbates the MCDAD signal reverses its sign when the (macroscopic) magnetization of the sample is reversed. This effect is caused by exchange splitting in connection with spin-orbit interaction and dipole selection rules. The results are compared to data of spin-resolved photo-electron spectroscopy and a similar experiment performed in the X-ray region at Fe 2p1/2 and 2p3/2 core levels.
    BibTeX:
    @article{Bansmann1992b,
      author = {Bansmann, J. and Westphal, C. and Getzlaff, M. and Fegel, F. and Schönhense, G.},
      title = {Magnetic circular dichroism in valence-band photo-emission from Fe(100)},
      journal = {Journal of Magnetism and Magnetic Materials},
      year = {1992},
      volume = {104-107},
      number = {Part 3},
      pages = {1691--1692},
      doi = {http://dx.doi.org/10.1016/0304-8853(92)91511-Q}
    }
    
    Bansmann, J., Ostertag, C., Schönhense, G., Fegel, F., Westphal, C., Getzlaff, M., Schäfers, F. & Petersen, H. Circular Dichroism in X-ray Photoemission from Core-Levels of Non-Magnetic Species 1992 Phys. Rev. B
    Vol. 46, pp. 13496 
    article DOI  
    BibTeX:
    @article{Bansmann1992c,
      author = {Bansmann, J. and Ostertag, Ch. and Schönhense, G. and Fegel, F. and Westphal, C. and Getzlaff, M. and Schäfers, F. and Petersen, H.},
      title = {Circular Dichroism in X-ray Photoemission from Core-Levels of Non-Magnetic Species},
      journal = {Phys. Rev. B},
      year = {1992},
      volume = {46},
      pages = {13496},
      doi = {http://dx.doi.org/10.1103/PhysRevB.46.13496}
    }
    
    Cherepkov, N. & Schönhense, G. Linear Dichroism in the Angular Distribution of Photoelectrons from Oriented Molecules 1992 Synchroton Radiation and Dynamic Phenomena: Proceedings of the 48th International Meeting of Physical Chemistry, Grenoble, France (Conference Proceedings), pp. 67-69  incollection  
    BibTeX:
    @incollection{Cherepkov1992,
      author = {Cherepkov, N.A. and Schönhense, G.},
      title = {Linear Dichroism in the Angular Distribution of Photoelectrons from Oriented Molecules},
      booktitle = {Synchroton Radiation and Dynamic Phenomena: Proceedings of the 48th International Meeting of Physical Chemistry, Grenoble, France (Conference Proceedings)},
      publisher = {Springer, Berlin},
      year = {1992},
      pages = {67--69},
      edition = {1}
    }
    
    Döhring, T., Schönhense, G. & Heinzmann, U. A circular polarizer for the region of windowless VUV radiation 1992 Measurement Science and Technology
    Vol. 3(1), pp. 91-97 
    article DOI  
    Abstract: A circular polarizer for the region of windowless VUV is described. The device consists of two four-mirror assemblies, using reflectivity differences and phase shifts at gold surfaces known from the Fresnel equations. Owing to its variable angle arrangement the polarizer can be used between 30 nm and 120 nm. When operated with Hel light (58.43 nm), a degree of circular polarization of more than 96% was achieved. The optical constants of gold have been determined by use of the transmitted intensity and polarization of the radiation.
    BibTeX:
    @article{Doehring1992,
      author = {Döhring, T. and Schönhense, G. and Heinzmann, U.},
      title = {A circular polarizer for the region of windowless VUV radiation},
      journal = {Measurement Science and Technology},
      year = {1992},
      volume = {3},
      number = {1},
      pages = {91--97},
      doi = {http://dx.doi.org/10.1088/0957-0233/3/1/013}
    }
    
    Getzlaff, M., Bansmann, J., Westphal, C. & Schönhense, G. Exchange splitting of adsorbate-induced bands on thin iron films 1992 Journal of Magnetism and Magnetic Materials
    Vol. 104-107(Part 3), pp. 1781-1782 
    article DOI  
    Abstract: Adsorbate-induced bands are investigated using energy-, angle- and spin-resolving photoelectron spectroscopy. With a ferromagnetic substrate these bands can show an exchange splitting. By means of epitaxial growth on W(110) or Au(100) we produced thin bcc iron films, layer-by-layer growth was monitored by means of MEED-oscillations. Spin-resolved spectra for different coverages with chemisorbed oxygen or CO or physisorbed Xe are shown. We found values of up to 1 eV exchange splitting of the oxygen 2p-derived band, analogous to prior measurements on bulk-crystals. Even for the physisorbed species magnetic interaction is evident. Aspects of the angular dependence as well as systematic differences of the line profiles of adsorbate-induced structures in the majority- and minority-spin channels are discussed.
    BibTeX:
    @article{Getzlaff1992,
      author = {Getzlaff, M. and Bansmann, J. and Westphal, C. and Schönhense, G.},
      title = {Exchange splitting of adsorbate-induced bands on thin iron films},
      journal = {Journal of Magnetism and Magnetic Materials},
      year = {1992},
      volume = {104-107},
      number = {Part 3},
      pages = {1781--1782},
      doi = {http://dx.doi.org/10.1016/0304-8853(92)91546-6}
    }
    
    Schönhense, G., Westphal, C., Bansmann, J. & Getzlaff, M. Circular Dichroism in Photoemission from Nonmagnetic, Low-Z Solids: A Conspicuous Effect of the Photon Spin 1992 Europhysics Letters
    Vol. 17(8), pp. 727-732 
    article DOI  
    Abstract: A new phenomenon has been observed in solid-state photoemission with circularly polarized light. Its outward appearance is similar to the circular dichroism in photoabsorption. For special observation geometries, large photoelectron intensity asymmetries arise upon reversal of the photon helicity. The effect is not based on spin-orbit interaction, as is demonstrated by the example of photoemission from graphite (Z&#160;=&#160;6). Similar asymmetries are expected for all single-crystal solids thus opening up a new class of experiments providing new tests for photoemission theories. Detailed information on the dynamics of photoexcitation of a solid can be gained, as discussed in terms of a simple orbital model.
    BibTeX:
    @article{Schoenhense1992,
      author = {Schönhense, G. and Westphal, C. and Bansmann, J. and Getzlaff, M.},
      title = {Circular Dichroism in Photoemission from Nonmagnetic, Low-Z Solids: A Conspicuous Effect of the Photon Spin},
      journal = {Europhysics Letters},
      year = {1992},
      volume = {17},
      number = {8},
      pages = {727--732},
      doi = {http://dx.doi.org/10.1209/0295-5075/17/8/011}
    }
    
    Schönhense, G. Circular dichroism in photoemission from oriented molecules at surfaces 1992 Proceedings of the International Workshop on Photoionization 1992/Berlin, Germany, pp. 217-220  incollection  
    BibTeX:
    @incollection{Schoenhense1992a,
      author = {Schönhense, G.},
      title = {Circular dichroism in photoemission from oriented molecules at surfaces},
      booktitle = {Proceedings of the International Workshop on Photoionization 1992/Berlin, Germany},
      publisher = {AMS Press Inc.},
      year = {1992},
      pages = {217--220}
    }
    
    Schönhense, G., Westphal, C., Bansmann, J., Getzlaff, M., Noffke, J. & Fritsche, L. Circular dichroism in photoemission from surfaces 1991 Surface Science Letters
    Vol. 251-252, pp. A314-135 
    article DOI  
    Abstract: Xe absorbed on Pd(111) in the dilute phase, in the (√3 × √3 )R30°, and in the (√7 ×7R19.2° structure has been studied by spin-resolved photoemission with normally incident circularly polarized light and for normal electron emission. Similar to the free atomic case, no splitting was observed for the dilute phase in the peak corresponding to the p3/2 hole state. Subthreshold electronic resonances were found for the two ordered layers, but could not be detected for the dilute phase. Consequences regarding the splitting mechanism and the excitation and emission processes for the resonances are discussed.
    BibTeX:
    @article{Schoenhense1991,
      author = {Schönhense, G. and Westphal, C. and Bansmann, J. and Getzlaff, M. and Noffke, J. and Fritsche, L.},
      title = {Circular dichroism in photoemission from surfaces},
      journal = {Surface Science Letters},
      year = {1991},
      volume = {251-252},
      pages = {A314--135},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.67.1318}
    }
    
    Vogt, B., Kessler, B., Müller, N., Schönhense, G., Schmiedeskamp, B. & Heinzmann, U. Spin-resolved photoemission from Xe on Pd(111) in the dilute phase: The model case of singly adsorbed atoms 1991 Phys. Rev. Lett.
    Vol. 67(10), pp. 1318-1321 
    article DOI  
    Abstract: Xe absorbed on Pd(111) in the dilute phase, in the (√3 × √3 )R30°, and in the (√7 ×7R19.2° structure has been studied by spin-resolved photoemission with normally incident circularly polarized light and for normal electron emission. Similar to the free atomic case, no splitting was observed for the dilute phase in the peak corresponding to the p3/2 hole state. Subthreshold electronic resonances were found for the two ordered layers, but could not be detected for the dilute phase. Consequences regarding the splitting mechanism and the excitation and emission processes for the resonances are discussed.
    BibTeX:
    @article{Vogt1991,
      author = {Vogt, B. and Kessler, B. and Müller, N. and Schönhense, G. and Schmiedeskamp, B. and Heinzmann, U.},
      title = {Spin-resolved photoemission from Xe on Pd(111) in the dilute phase: The model case of singly adsorbed atoms},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1991},
      volume = {67},
      number = {10},
      pages = {1318--1321},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.67.1318}
    }
    
    Westphal, C., Bansmann, J., Getzlaff, M., Schönhense, G., Cherepkov, N.A., Braunstein, M., McKoy, V. & Dubs, R.L. Circular dichroism in photoemission from oriented molecules at surfaces 1991 Surface Science Letters
    Vol. 253(1-3), pp. A447-A448 
    article DOI  
    BibTeX:
    @article{Westphal1991,
      author = {Westphal, C. and Bansmann, J. and Getzlaff, M. and Schönhense, G. and Cherepkov, N. A. and Braunstein, M. and McKoy, V. and Dubs, R. L.},
      title = {Circular dichroism in photoemission from oriented molecules at surfaces},
      journal = {Surface Science Letters},
      year = {1991},
      volume = {253},
      number = {1-3},
      pages = {A447--A448},
      doi = {http://dx.doi.org/10.1016/0167-2584(91)90388-8}
    }
    
    Donath, M., Schönhense, G., Ertl, K. & Dose, V. Influence of Surface Roughness and Chemisorption on Magnetic Hysteresis Curves of a Ni(110)-Surface Observed by Spin-Resolved Inverse Photoemission 1990 Appl. Phys. A
    Vol. 50, pp. 49 
    article DOI  
    BibTeX:
    @article{Donath1990,
      author = {Donath, M. and Schönhense, G. and Ertl, K. and Dose, V.},
      title = {Influence of Surface Roughness and Chemisorption on Magnetic Hysteresis Curves of a Ni(110)-Surface Observed by Spin-Resolved Inverse Photoemission},
      journal = {Appl. Phys. A},
      year = {1990},
      volume = {50},
      pages = {49},
      doi = {http://dx.doi.org/10.1007/BF00323954}
    }
    
    Mank, A., Drescher, M., Huth-Fehre, T., Schönhense, G., Bowering, N. & Heinzmann, U. Photoelectron dynamics of HI ionized by coherent VUV radiation 1990 Journal of Electron Spectroscopy and Related Phenomena
    Vol. 52, pp. 661-670 
    article DOI  
    Abstract: The asymmetry parameter [beta] of the photoelectron angular distribution in photoionization of the molecule HI was measured using a tunable coherent VUV source. The target was cooled to a rotational temperature of less than 20 K by a supersonic beam expansion. The data show pronounced resonance structure which is compared to results on a target at nearly room temperature and to an ab-initio calculation by H. Lefebvre-Brion and coworkers.
    BibTeX:
    @article{Mank1990,
      author = {Mank, A. and Drescher, M. and Huth-Fehre, T. and Schönhense, G. and Bowering, N. and Heinzmann, U.},
      title = {Photoelectron dynamics of HI ionized by coherent VUV radiation},
      journal = {Journal of Electron Spectroscopy and Related Phenomena},
      year = {1990},
      volume = {52},
      pages = {661--670},
      doi = {http://dx.doi.org/10.1016/0368-2048(90)85055-E}
    }
    
    Schönhense, G. Spin-dependent effects in photoemission 1990 Vacuum
    Vol. 41(1-3)Surface Science Section, pp. 506-510 
    article DOI  
    Abstract: A brief overview is presented of the photon and electron-spin dependent effects in photoemission from surfaces. In addition to the well-established techniques of optical spin orientation with circularly polarized light and spin-polarized photoemission from ferromagnets, a third class of experiments is introduced. This phenomenon is termed circular dichroism in photoemission. It occurs in a pure electric dipole transition and does not require spin-orbit nor exchange interaction. Typical examples of all three categories are discussed.
    BibTeX:
    @article{Schoenhense1990,
      author = {Schönhense, G},
      title = {Spin-dependent effects in photoemission},
      booktitle = {Surface Science Section},
      journal = {Vacuum},
      year = {1990},
      volume = {41},
      number = {1-3},
      pages = {506--510},
      doi = {http://dx.doi.org/10.1016/0042-207X(90)90399-J}
    }
    
    Schönhense, G. Circular dichroism and spin polarization in photoemission from adsorbates and non-magnetic solids 1990 Physica Scripta
    Vol. 31(T), pp. 255-+ 
    article DOI  
    Abstract: Spin-resolving techniques in photoemission are presently attracting wide interest because they can provide a detailed insight into specific aspects of electronic structure and the dynamics of the photoexcitation process. Recent experimental work in the field of non-magnetic systems is reviewed with emphasis on the complementary nature of the information gained by exploiting the photon- and/or electron-spin. A very promising achievement is the verification of circular dichroism (CDAD) in the angular distribution of photoelectrons. It arises without spin-orbit interaction through an interference of final-state partial waves. Every aligned or oriented target (molecular adsorbates, single crystals) should in principle show this effect in photoemission with circularly polarized light. Electron-spin polarization (ESP) in photoemission is induced by circularly polarized light as a direct consequence of spin-orbit interaction. This type of spectroscopy thus provides a unique method for determining the symmetries of electronic bands of high-Z materials. Recent examples of both categories are discussed.
    BibTeX:
    @article{Schoenhense1990a,
      author = {Schönhense, G.},
      title = {Circular dichroism and spin polarization in photoemission from adsorbates and non-magnetic solids},
      journal = {Physica Scripta},
      year = {1990},
      volume = {31},
      number = {T},
      pages = {255-+},
      doi = {http://dx.doi.org/10.1088/0031-8949/1990/T31/035}
    }
    
    Westphal, C., Bansmann, J., Getzlaff, M. & Schönhense, G. Experimental observation of circular dichroism in photoemission 1990 Vacuum
    Vol. 41(1-3)Surface Science Section, pp. 87-89 
    article DOI  
    Abstract: A new phenomenon in photoemission from adsorbates is reported. With circularly polarized synchrotron radiation and a special observation geometry (defining a `handedness' of the directions of photon impact, electron ejection and surface normal) photoemission intensity asymmetries arise upon reversal of photon helicity. Circular Dichroism in the Angular Distribution of photoelectrons (CDAD) has been theoretically predicted in the pure electric dipole approximation. The phenomenon should occur for all molecular adsorbates which are spatially oriented. First experimental results for a diatomic molecule (CO), a polyatomic molecule (benzene) and a molecule with significant spin-orbit interaction (CH3l) revealed CDAD asymmetries in all the photoemission signals corresponding to the various molecular orbitals.
    BibTeX:
    @article{Westphal1990,
      author = {Westphal, C and Bansmann, J and Getzlaff, M and Schönhense, G},
      title = {Experimental observation of circular dichroism in photoemission},
      booktitle = {Surface Science Section},
      journal = {Vacuum},
      year = {1990},
      volume = {41},
      number = {1-3},
      pages = {87--89},
      doi = {http://dx.doi.org/10.1016/0042-207X(90)90281-3}
    }
    
    Westphal, C., Bansmann, J., Getzlaff, M. & Schönhense, G. Information on structure and photoemission dynamics of molecular absorbates from circular dichroism in photoemission 1990 Journal of Electron Specroscopy and Related Phenomena
    Vol. 52, pp. 613-622 
    article DOI  
    Abstract: Measurements of photoemission-intensity asymmetries for right- and left-circularly polarized light are reported as a method to investigate the structure and photoemission dynamics of molecular adsorbates. With circularly polarized synchrotron radiation and a special geometry circular dichroism in the angular distribution of photoelectrons (CDAD) is observed. The effect occurs in pure electric dipole approximation and does not require spin-orbit interaction, the measured asymmetries are of the same order of magnitude as the differential cross-section itself. Experimental studies of NO and benzene adsorbed on single-crystal surfaces are presented.
    BibTeX:
    @article{Westphal1990a,
      author = {Westphal, C. and Bansmann, J. and Getzlaff, M. and Schönhense, G.},
      title = {Information on structure and photoemission dynamics of molecular absorbates from circular dichroism in photoemission},
      journal = {Journal of Electron Specroscopy and Related Phenomena},
      year = {1990},
      volume = {52},
      pages = {613--622},
      doi = {http://dx.doi.org/10.1016/0368-2048(90)85052-B}
    }
    
    Mank, A., Drescher, M., Huth-Fehre, T., Schonhense, G., Bowering, N. & Heinzmann, U. Angular distribution of photoelectrons ejected from HI by polarised coherent VUV radiation 1989 Journal of Physics B
    Vol. 22(17), pp. L487-L491 
    article DOI  
    Abstract: The asymmetry parameter beta of the photoelectron angular distribution of the process HI(5 pi 4) 1 Sigma + ( upsilon &quot;=0)+hv to HI+(5 pi 3) 2 Pi 3/2 ( upsilon '=0)+e- was measured at photon energies from 86440 to 87000 cm-1. The data show resonance structure due to autoionisation that was not resolved before. The results are compared with predictions of an ab initio calculation by H Lefebvre-Brion and co-workers (1985).
    BibTeX:
    @article{Mank1989,
      author = {Mank, A. and Drescher, M. and Huth-Fehre, T. and Schonhense, G. and Bowering, N. and Heinzmann, U.},
      title = {Angular distribution of photoelectrons ejected from HI by polarised coherent VUV radiation},
      journal = {Journal of Physics B},
      year = {1989},
      volume = {22},
      number = {17},
      pages = {L487--L491},
      doi = {http://dx.doi.org/10.1088/0953-4075/22/17/003}
    }
    
    Westphal, C., Bansmann, J., Getzlaff, M. & Schönhense, G. Circular dichroism in the angular distribution of photoelectrons from oriented CO molecules 1989 Phys. Rev. Lett.
    Vol. 63(2), pp. 151-154 
    article DOI  
    Abstract: Theoretical predictions of a new phenomenon arising in photoelectron emission from oriented molecules by circularly polarized light have been experimentally verified for CO. For a special geometry photoelectron-intensity differences occur upon reversal of photon helicity. The measured asymmetries (up to 80%) show good agreement with an ab initio calculation at photon energies between 20 and 40 eV. Theoretically, the new manifestation of circular dichroism is already obtained in the pure electric dipole approximation without inclusion of spin-orbit interaction.
    BibTeX:
    @article{Westphal1989,
      author = {Westphal, C. and Bansmann, J. and Getzlaff, M. and Schönhense, G.},
      title = {Circular dichroism in the angular distribution of photoelectrons from oriented CO molecules},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1989},
      volume = {63},
      number = {2},
      pages = {151--154},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.63.151}
    }
    
    Böwering, N., Huth, T., Mank, A., Müller, M., Schönhense, G., Wallenstein, R. & Heinzmann, U. Photoelectron spectroscopy of HI and photoemission following narrowband VUV excitation 1988 Electron-Molecule Scattering and Photoionization, pp. 139-+  incollection URL 
    BibTeX:
    @incollection{Boewering1988,
      author = {Böwering, N. and Huth, T. and Mank, A. and Müller, M. and Schönhense, G. and Wallenstein, R. and Heinzmann, U.},
      title = {Photoelectron spectroscopy of HI and photoemission following narrowband VUV excitation},
      booktitle = {Electron-Molecule Scattering and Photoionization},
      publisher = {Plenum Press, New York},
      year = {1988},
      pages = {139-+},
      url = {http://adsabs.harvard.edu/abs/1988emsp.conf..139B}
    }
    
    Decker, H., Connelly, P.R., Robert, C.H. & Gill, S.J. Nested allosteric interaction in tarantula hemocyanin revealed through the binding of oxygen and carbon monoxide 1988 Biochemistry
    Vol. 27(18), pp. 6901-6908 
    article DOI  
    BibTeX:
    @article{Decker1988,
      author = {Decker, H. and Connelly, P. R. and Robert, Ch. H. and Gill, S. J.},
      title = {Nested allosteric interaction in tarantula hemocyanin revealed through the binding of oxygen and carbon monoxide},
      journal = {Biochemistry},
      publisher = {American Chemical Society},
      year = {1988},
      volume = {27},
      number = {18},
      pages = {6901--6908},
      doi = {http://dx.doi.org/10.1021/bi00418a036}
    }
    
    Huth, T., Mank, A., Böwering, N., Schönhense, G., Wallenstein, R. & Heinzmann, U. Photoelectron Emission from HI using Narrow-Band, Polarized, Coherent VUV-Radiation 1988 Physics of Electronics and Atomic Collisions, pp. 607  incollection  
    BibTeX:
    @incollection{Huth1988,
      author = {Huth, T. and Mank, A. and Böwering, N. and Schönhense, G. and Wallenstein, R. and Heinzmann, U.},
      title = {Photoelectron Emission from HI using Narrow-Band, Polarized, Coherent VUV-Radiation},
      booktitle = {Physics of Electronics and Atomic Collisions},
      publisher = {Elsevier},
      year = {1988},
      pages = {607}
    }
    
    Schafers, F., Heckenkamp, C., Schonhense, G. & Heinzmann, U. Energy dependence of the electron spin polarisation parameters for Hg 5d photoionisation with circularly polarised light 1988 Journal of Physics B
    Vol. 21(5), pp. 769-774 
    article DOI  
    Abstract: Circularly polarised VUV radiation from the storage ring BESSY was used to measure all three spin polarisation parameters of photoelectrons from the Hg 5d shell in the photon energy range from threshold to approximately 35 eV. The experimental results are compared with theoretical calculations in the relativistic and non-relativistic random-phase-approximation scheme (RRPA and RPAE respectively) and Dirac-Slater (DS) calculations. A discussion of the influence of relativistic and potential barrier effects on the experimental data is given.
    BibTeX:
    @article{Schafers1988,
      author = {Schafers, F. and Heckenkamp, C. and Schonhense, G. and Heinzmann, U.},
      title = {Energy dependence of the electron spin polarisation parameters for Hg 5d photoionisation with circularly polarised light},
      journal = {Journal of Physics B},
      year = {1988},
      volume = {21},
      number = {5},
      pages = {769--774},
      doi = {http://dx.doi.org/10.1088/0953-4075/21/5/008}
    }
    
    Schmiedeskamp, B., Kessler, B., Muller, N., Schonhense, G. & Heinzmann, U. Spin-resolved photoemission from Pd(111) 1988 Solid State Communications
    Vol. 65(7), pp. 665-670 
    article DOI  
    Abstract: Circularly polarized synchrotron radiation of BESSY and spin-resolved photoemission have been used for a study of the electronic structure of Pd in [Lambda]-direction. The photon energies were chosen between the photoemission threshold at 5.7 and 23 eV. We used the highly symmetric experimental setup of normal light incidence and normal photoelectron emission and studied transitions from the two [Lambda]36/[Lambda]34.5-band-pairs split by spin-orbit interaction. Though the magnitude of the spin-orbit splittings [Delta]Eso in this medium-Z material is smaller than lifetime broadening, it is feasible to resolve the spin-orbit splitting of the initial states via photoelectron spin analysis. The data are consistent with a bandstructure calculation of Noffke and Eckardt except for an energy dependent shift of 0.4 to 1.1 eV of the final bands towards higher energies. In the occupied part of the bandstructure an avoided crossing could be identified. Surface- (bandgap-) emission was observed for photon energies below 7.8 eV.
    BibTeX:
    @article{Schmiedeskamp1988,
      author = {Schmiedeskamp, B. and Kessler, B. and Muller, N. and Schonhense, G. and Heinzmann, U.},
      title = {Spin-resolved photoemission from Pd(111)},
      journal = {Solid State Communications},
      year = {1988},
      volume = {65},
      number = {7},
      pages = {665--670},
      doi = {http://dx.doi.org/10.1016/0038-1098(88)90360-2}
    }
    
    Schönhense, G., Getzlaff, M., Westphal, C., Heidemann, B. & Bansmann, J. Exchange Splitting of Adsorbate-induced Bands in Chemisorption on Ferromagnetic 3d-Metals 1988 Journal de Physique
    Vol. 49(C8), pp. 1643 
    article  
    BibTeX:
    @article{Schoenhense1988,
      author = {Schönhense, G. and Getzlaff, M. and Westphal, C. and Heidemann, B. and Bansmann, J.},
      title = {Exchange Splitting of Adsorbate-induced Bands in Chemisorption on Ferromagnetic 3d-Metals},
      journal = {Journal de Physique},
      year = {1988},
      volume = {49},
      number = {C8},
      pages = {1643}
    }
    
    Schoenhense, G., Donath, M., Kolac, U. & Dose, V. Exchange splitting of an oxygen 2p-derived band at Ni(100) 1988 Surface Science
    Vol. 206(3), pp. L888-L894 
    article DOI  
    Abstract: Employing spin-resolved inverse photoemission we have observed an exchange splitting of the unoccupied oxygen-induced band in the chemisorption system (2 x 1)-O/Ni(110). At the centre of the surface Brillouin zone the splitting between the oxygen 2p-derived majority and minority band-- referred to the magnetization vector of nickel-was found to be 80+/-20 meV. This effect is a manifestation of the strong magnetic correlation between the oxygen and nickel bands. The size of the splitting is surprising as earlier experimental work indicated a substantial reduction of the surface magnetization due to chemisorption. For the empty 2[pi]*-derived band of CO on Ni(110) no such splitting has been observed.
    BibTeX:
    @article{Schoenhense1988a,
      author = {Schoenhense, G. and Donath, M. and Kolac, U. and Dose, V.},
      title = {Exchange splitting of an oxygen 2p-derived band at Ni(100)},
      journal = {Surface Science},
      year = {1988},
      volume = {206},
      number = {3},
      pages = {L888--L894},
      doi = {http://dx.doi.org/10.1016/0039-6028(88)90131-8}
    }
    
    Kessler, B., Eyers, A., Horn, K., Müller, N., Schmiedeskamp, B., Schönhense, G. & Heinzmann, U. Determination of xenon valence and conduction bands by spin-polarized photoemission 1987 Phys. Rev. Lett.
    Vol. 59(3), pp. 331-334 
    article DOI  
    Abstract: Using circularly polarized synchrotron radiation and spin-resolved photoemission, we have studied the valence and conduction bands of Xe(111) up to about 18 eV above the valence-band maximum. Direct information about the symmetry of bands and their hybridization is provided by photoelectron spin polarization. Our data also prove the existence of a gap in the unoccupied bands above the fundamental gap. A comparison of our data with calculated band structures shows the importance of an energy-dependent self-energy correction.
    BibTeX:
    @article{Kessler1987,
      author = {Kessler, B. and Eyers, A. and Horn, K. and Müller, N. and Schmiedeskamp, B. and Schönhense, G. and Heinzmann, U.},
      title = {Determination of xenon valence and conduction bands by spin-polarized photoemission},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1987},
      volume = {59},
      number = {3},
      pages = {331--334},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.59.331}
    }
    
    Müller, N., Kessler, B., Schmiedeskamp, B., Schonhense, G. & Heinzmann, U. Spin-resolved photoemission from Ir(111): Transitions into a secondary band and energetic position of the final state bands 1987 Solid State Communications
    Vol. 61(3), pp. 187-192 
    article DOI  
    Abstract: Spin resolved photoelectron spectroscopy with Ir(111) was performed in normal incidence of circularly polarized VUV radiation and normal electron emission. Using the spin information the spectra were separated with regard to the symmetry of the initial states. Besides the dominant transitions into the free electron like parts of the unoccupied bands, transitions into a secondary unoccupied band were unambiguously identified. Transitions into this secondary band cannot be evidenced without spin analysis. The data are in excellent agreement with a fully relativistic first-principles band structure calculation of Noffke and Fritsche, except for an overall shift of [Delta][var epsilon] = 0.8 eV +/-0.3 eV for the energy of the unoccupied final bands.
    BibTeX:
    @article{Mueller1987,
      author = {Müller, N. and Kessler, B. and Schmiedeskamp, B. and Schonhense, G. and Heinzmann, U.},
      title = {Spin-resolved photoemission from Ir(111): Transitions into a secondary band and energetic position of the final state bands},
      journal = {Solid State Communications},
      year = {1987},
      volume = {61},
      number = {3},
      pages = {187--192},
      doi = {http://dx.doi.org/10.1016/0038-1098(87)90027-5}
    }
    
    Schönhense, G., Kessler, B., Müller, N., Schmiedeskamp, B. & Heinzmann, U. Electronic Resonances in Rare-Gas Adsorbates Observed by Spin-Resolved Electron Spectroscopy 1987 Physica Scripta
    Vol. 35(4), pp. 541-546 
    article DOI  
    Abstract: Recent experimental results of spin-polarized electron emission following photoexcitation of the valence orbitals of adsorbed rare-gas atoms are presented. As light source we employed the circularly polarized synchrotron radiation from the storage ring BESSY (Berlin). As detection technique served angle- and spin-resolved electron spectroscopy. The resolution of the experimental method is demonstrated by the example of photoemission from Ar on Pt(111), where a doublet feature with a splitting of only 90 meV could be resolved, which is hardly discernible in intensity spectroscopy. Below the threshold for direct photoemission narrow electronic resonances have been observed, resulting from discrete np - n's excitations in the adsorbate. For the system Xe on Ir(111) the dependence of the resonance features on the coverage from the sub-monolayer regime up to the 3D-crystal is discussed.
    BibTeX:
    @article{Schoenhense1987,
      author = {Schönhense, G. and Kessler, B. and Müller, N. and Schmiedeskamp, B. and Heinzmann, U.},
      title = {Electronic Resonances in Rare-Gas Adsorbates Observed by Spin-Resolved Electron Spectroscopy},
      journal = {Physica Scripta},
      year = {1987},
      volume = {35},
      number = {4},
      pages = {541--546},
      doi = {http://dx.doi.org/10.1088/0031-8949/35/4/024}
    }
    
    Bona, G.L., Meier, F., Schönhense, G. & Siegmann, H.C. Spin polarized photoemission with pulsed laser irradiation of iron 1986 Journal of Magnetism and Magnetic Materials
    Vol. 54-57(Part 2), pp. 809-810 
    article DOI  
    Abstract: The spin polarization P of electrons emitted from polycrystalline iron by a pulsed KrF-excimer laser shows an unexpected dependence on the intensity of the radiation. At sufficiently reduced power densities P is 58%, increasing to 100% for a certain range of higher pulse energies. Increasing the laser power further the spins of the emitted electrons become more and more disordered, showing ultimately P = 0.
    BibTeX:
    @article{Bona1986,
      author = {Bona, G. L. and Meier, F. and Schönhense, G. and Siegmann, H. C.},
      title = {Spin polarized photoemission with pulsed laser irradiation of iron},
      journal = {Journal of Magnetism and Magnetic Materials},
      year = {1986},
      volume = {54-57},
      number = {Part 2},
      pages = {809--810},
      doi = {http://dx.doi.org/10.1016/0304-8853(86)90264-7}
    }
    
    Heckenkamp, C., Eyers, A., Schäfers, F., Schöhense, G. & Heinzmann, U. A rotatable electron spectrometer system for spin- and angle-resolved photoemission experiments with circularly polarized synchrotron radiation 1986 Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
    Vol. 246(1-3), pp. 500-503 
    article DOI  
    Abstract: An electron-optical system is described which has been especially designed for spin- and angle-resolved photoelectron spectroscopy with circularly polarized synchrotron radiation. One hv- and one uhv-type of this system (for studies at atoms/molecules and solids/adsorbates, respectively) are in operation at the storage ring BESSY. The system employs, thus, a light source and an electron spin detector (high energy Mott detector) both fixed in space. This is realized by a rotatable electron spectrometer and a 90[degree sign] deflector by which the electron beam is directed along the axis of rotation of the spectrometer, independent of the emission angle chosen.
    BibTeX:
    @article{Heckenkamp1986,
      author = {Heckenkamp, Ch. and Eyers, A. and Schäfers, F. and Schöhense, G. and Heinzmann, U.},
      title = {A rotatable electron spectrometer system for spin- and angle-resolved photoemission experiments with circularly polarized synchrotron radiation},
      journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
      year = {1986},
      volume = {246},
      number = {1-3},
      pages = {500--503},
      doi = {http://dx.doi.org/10.1016/0168-9002(86)90139-7}
    }
    
    Heckenkamp, C., Schäfers, F., Schönhense, G. & Heinzmann, U. Experimental Characterization of the Xe 5p Photoionization by Angle- and Spin-Resolved Photoelectron Spectroscopy 1986 Z Phys. D
    Vol. 2, pp. 257 
    article DOI  
    BibTeX:
    @article{Heckenkamp1986a,
      author = {Heckenkamp, Ch. and Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Experimental Characterization of the Xe 5p Photoionization by Angle- and Spin-Resolved Photoelectron Spectroscopy},
      journal = {Z Phys. D},
      year = {1986},
      volume = {2},
      pages = {257},
      doi = {http://dx.doi.org/10.1007/BF01426231}
    }
    
    Schäfers, F., Peatman, W., Eyers, A., Heckenkamp, C., Schönhense, G. & Heinzmann, U. High-flux normal incidence monochromator for circularly polarized synchrotron radiation 1986 Review of Scientific Instruments
    Vol. 57, pp. 1032 
    article DOI  
    Abstract: A 6.5-m normal incidence monochromator installed at the storage ring BESSY, which is optimized for a high throughput of circularly polarized off-plane radiation at moderate resolution is described. The monochromator employs two exit slits and is specially designed and used for low-signal experiments such as spin- and angle-resolved photoelectron spectroscopy on solids, adsorbates, free atoms, and molecules. The Monk–Gillieson mounting (plane grating in a convergent light beam) allows for large apertures with relatively little astigmatism. With two gratings, a flux of more than 1011 photons s−1 bandwidth−1 (0.2–0.5 nm) with a circular polarization of more than 90% in the wavelength range from 35 to 675 nm is achieved.
    BibTeX:
    @article{Schaefers1986,
      author = {Schäfers, F. and Peatman, W. and Eyers, A. and Heckenkamp, C. and Schönhense, G. and Heinzmann, U.},
      title = {High-flux normal incidence monochromator for circularly polarized synchrotron radiation},
      journal = {Review of Scientific Instruments},
      publisher = {AIP},
      year = {1986},
      volume = {57},
      pages = {1032},
      doi = {http://dx.doi.org/10.1063/1.1138655}
    }
    
    Schönhense, G. Photoelectron spin-polarization spectroscopy: A new method in adsorbate physics 1986 Applied Physics A: Materials Science & Processing
    Vol. 41, pp. 39-60 
    article DOI  
    Abstract: Energy-, angle-, and spin-resolved photoemission results from adsorbates are discussed. The measurements employed circularly polarized synchrotron radiation from BESSY, a special photoelectron spectrometer, and a Mott detector for electron spin-polarization (ESP) analysis. It is demonstrated by the example of physisorbed Xe, Kr, and Ar atoms how this method provides independent information complementary to intensity spectroscopy. Almost complete ESP parallel or antiparallel to the photon spin measured at certain conditions allowed a direct assignment of symmetries of electronic states. Sharp photon-inducednprarr n's resonances (DeltaE<80 meV) have been observed, which show only small relaxation shifts compared to the gas phase. The ESP provided an unambiguous quantum-number labelling of the transitions and revealed an additional line splitting due to symmetry lowering on the surface. Photo-ESP spectroscopy is further demonstrated as to increase spectral resolution, to gain an insight into dynamical relaxation mechanisms of electronically excited adsorbates, and to be a sensitive probe of the ldquolocalrdquo symmetry. A detailed discussion is given of line positions and ESP when going from a commensurate overlayer via an incommensurate monolayer and multilayers of different thickness onto a 3D rare-gas crystal.
    BibTeX:
    @article{Schoenhense1986,
      author = {Schönhense, G.},
      title = {Photoelectron spin-polarization spectroscopy: A new method in adsorbate physics},
      journal = {Applied Physics A: Materials Science & Processing},
      year = {1986},
      volume = {41},
      pages = {39-60},
      doi = {http://dx.doi.org/10.1007/BF00618533}
    }
    
    Schönhense, G., Eyers, A. & Heinzmann, U. Sharp photon-induced np(n+1)s resonances in Xe and Kr monolayers observed by spin-resolved electron spectroscopy 1986 Phys. Rev. Lett.
    Vol. 56(5), pp. 512-515 
    article DOI  
    Abstract: Narrow Xe 5p→6s and Kr 4p→5s resonances (ΔE<80 meV) have been observed in the adsorbate phase on Pt(111) and graphite (0001). The photon-induced transitions reveal an additional level splitting compared to the gas phase and the intensities show a significant substrate dependence. The resonances were detected via spectroscopy of the electrons emitted due to a subsequent relaxation decay of the excited state. Measurement of the electron-spin polarization clarified the nature of the new decay mechanism observed and furthermore provided an unambiguous quantum-number labeling of the resonances.
    BibTeX:
    @article{Schoenhense1986a,
      author = {Schönhense, G. and Eyers, A. and Heinzmann, U.},
      title = {Sharp photon-induced np(n+1)s resonances in Xe and Kr monolayers observed by spin-resolved electron spectroscopy},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1986},
      volume = {56},
      number = {5},
      pages = {512--515},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.56.512}
    }
    
    Schönhense, G. & Heinzmann, U. Reply on the Comment by C. P. Flynn 1986 Phys. Rev. Lett.
    Vol. 57, pp. 268 
    article  
    BibTeX:
    @article{Schoenhense1986b,
      author = {Schönhense, G. and Heinzmann, U.},
      title = {Reply on the Comment by C. P. Flynn},
      journal = {Phys. Rev. Lett.},
      year = {1986},
      volume = {57},
      pages = {268}
    }
    
    Bona, G.L., Meier, F., Schönhense, G. & Siegmann, H.C. Completely Polarized Electrons Emitted from Polycrystalline Iron upon Pulsed Laser Irradiation 1985 Phys. Rev. Lett.
    Vol. 55(10), pp. 1121-1123 
    article DOI  
    Abstract: The spin polarization of the electrons emitted from iron by irradiation with a laser pulse has been measured as a function of the intensity of the radiation. For a certain range of pulse energies the spin polarization reaches 100%, i.e., all electrons are emitted with their magnetic moment parallel to the direction of magnetization.
    BibTeX:
    @article{Bona1985,
      author = {Bona, G. L. and Meier, F. and Schönhense, G. and Siegmann, H. C.},
      title = {Completely Polarized Electrons Emitted from Polycrystalline Iron upon Pulsed Laser Irradiation},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1985},
      volume = {55},
      number = {10},
      pages = {1121--1123},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.55.1121}
    }
    
    Eyers, A., Schonhense, G., Friess, U., Schafers, F. & Heinzmann, U. Influence of temperature and of physisorbed Xe/Kr on the spin resolved photoemission from Pt(111) 1985 Surface Science
    Vol. 162(1-3), pp. 96-102 
    article DOI  
    Abstract: Spin polarized photoemission from Pt(111) has been studied under normal incidence and normal emission as function of the temperature between 30 and 550 K using circularly polarized synchrotron radiation of BESSY. The photoelectron intensities and the electron spin polarizations are reduced with increasing temperature and also by increasing coverage of physisorbed rare gas atoms.
    BibTeX:
    @article{Eyers1985,
      author = {Eyers, A. and Schonhense, G. and Friess, U. and Schafers, F. and Heinzmann, U.},
      title = {Influence of temperature and of physisorbed Xe/Kr on the spin resolved photoemission from Pt(111)},
      journal = {Surface Science},
      year = {1985},
      volume = {162},
      number = {1-3},
      pages = {96--102},
      doi = {http://dx.doi.org/10.1016/0039-6028(85)90879-9}
    }
    
    Heckenkamp, C., Schäfers, F., Schönhense, G. & Heinzmann, U. Resonance of the photoelectron spin-polarization parameters in the 5p auto-ionization range of xenon 1985 Phys. Rev. A
    Vol. 32, pp. 1252 
    article DOI  
    BibTeX:
    @article{Heckenkamp1985,
      author = {Heckenkamp, Ch. and Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Resonance of the photoelectron spin-polarization parameters in the 5p auto-ionization range of xenon},
      journal = {Phys. Rev. A},
      year = {1985},
      volume = {32},
      pages = {1252},
      doi = {http://dx.doi.org/10.1103/PhysRevA.32.1252}
    }
    
    Kaesdorf, S., Schönhense, G. & Heinzmann, U. Experimental angular-resolved photoelectron spectroscopy of free oriented CH3I molecules 1985 Phys. Rev. Lett.
    Vol. 54(9), pp. 885-888 
    article DOI  
    Abstract: A photoionization experiment on free oriented molecules in the gas phase has been performed. CH3I molecules in a supersonic beam have been oriented with respect to the molecular axis parallel to an external field by use of an electric hexapole. The photoelectrons ejected by vacuum ultraviolet radiation in a region of a very weak field from the lone-pair orbital located at the iodine atom show a pronounced asymmetry depending on whether electrons are emitted parallel or antiparallel to the molecular axis.
    BibTeX:
    @article{Kaesdorf1985,
      author = {Kaesdorf, S. and Schönhense, G. and Heinzmann, U.},
      title = {Experimental angular-resolved photoelectron spectroscopy of free oriented CH3I molecules},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1985},
      volume = {54},
      number = {9},
      pages = {885--888},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.54.885}
    }
    
    Oepen, H.P., Hünlich, K., Kirschner, J., Eyers, A., Schafers, F., Schönhense, G. & Heinzmann, U. Experimental symmetry analysis of energy bands near critical points in Pt using spin- and momentum-resolved photoemission 1985 Phys. Rev. B
    Vol. 31(10), pp. 6846-6848 
    article DOI  
    Abstract: A theoretical discrepancy concerning band crossings at two points along the Λ direction in Pt is clarified by experimental symmetry analysis of the band characteristics, using circularly polarized synchrotron radiation and spin analysis of the photoelectrons by a new low-energy-diffraction analyzer system. Each of the theoretical results is found to be correct at one k point and incorrect at the other one.
    BibTeX:
    @article{Oepen1985,
      author = {Oepen, H. P. and Hünlich, K. and Kirschner, J. and Eyers, A. and Schafers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Experimental symmetry analysis of energy bands near critical points in Pt using spin- and momentum-resolved photoemission},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {1985},
      volume = {31},
      number = {10},
      pages = {6846--6848},
      doi = {http://dx.doi.org/10.1103/PhysRevB.31.6846}
    }
    
    Schönhense, G., Eyers, A., Friess, U., Schäfers, F. & Heinzmann, U. Highly Spin-Polarized Photoemission near Threshold from Physisorbed Xenon and Krypton Atoms 1985 Phys. Rev. Lett.
    Vol. 54(6), pp. 547-550 
    article DOI  
    Abstract: By use of circularly polarized synchrotron radiation at BESSY, spin-polarized photoemission from the valence orbitals of Xe and Kr atoms adsorbed on the Pt(111) single-crystal surface has been studied. Under certain conditions almost complete photoelectron polarization parallel or antiparallel to the photon spin was observed, allowing a direct assignment of quantum numbers of the states involved. Highly resolved intensity and polarization spectra in the threshold region exhibit pronounced variations versus photon energy.
    BibTeX:
    @article{Schoenhense1985,
      author = {Schönhense, G. and Eyers, A. and Friess, U. and Schäfers, F. and Heinzmann, U.},
      title = {Highly Spin-Polarized Photoemission near Threshold from Physisorbed Xenon and Krypton Atoms},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1985},
      volume = {54},
      number = {6},
      pages = {547--550},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.54.547}
    }
    
    Schönhense, G. & Heinzmann, H. Spin-resolved photoemission from nonmagnetic metals and adsorbates 1985 Polarized electrons in surface physics, pp. 468-512  incollection URL 
    BibTeX:
    @incollection{Schoenhense1985a,
      author = {Schönhense, G. and Heinzmann, H.},
      title = {Spin-resolved photoemission from nonmagnetic metals and adsorbates},
      booktitle = {Polarized electrons in surface physics},
      publisher = {World Scientific, Singapore},
      year = {1985},
      pages = {468-512},
      url = {http://books.google.de/books?hl=en&lr=&id=d-z-sb7eUOAC&oi=fnd&pg=PA467&dq=Spin-resolved+photoemission+from+nonmagnetic+metals+and+adsorbates&ots=4-nAxPb8WC&sig=vh3GrqMIcKJ9JsV5Un4LWOUBNSg&output=html}
    }
    
    Eyers, A., Schäfers, F., Schönhense, G., Heinzmann, U., Oepen, H.P., Hünlich, K., Kirschner, J. & Borstel, G. Characterization of Symmetry Properties of Pt(111) Electron Bands by Means of Angle-, Energy-, and Spin-Resolved Photoemission with Circularly Polarized Synchrotron Radiation 1984 Phys. Rev. Lett.
    Vol. 52(17), pp. 1559-1562 
    article DOI  
    Abstract: An angle-, energy-, and spin-resolved photoemission experiment has been performed for Pt(111) with the circularly polarized synchrotron radiation of the new German dedicated storage ring BESSY. The photoelectron polarization measured as function of the kinetic energy at different photon energies between 6.5 and 24 eV for normal incidence and normal emission shows a pronounced spectral variation up to ±55%. The electron intensities and polarizations observed allow a symmetry-resolved band characterization of Pt in the Γ-L direction.
    BibTeX:
    @article{Eyers1984,
      author = {Eyers, A. and Schäfers, F. and Schönhense, G. and Heinzmann, U. and Oepen, H. P. and Hünlich, K. and Kirschner, J. and Borstel, G.},
      title = {Characterization of Symmetry Properties of Pt(111) Electron Bands by Means of Angle-, Energy-, and Spin-Resolved Photoemission with Circularly Polarized Synchrotron Radiation},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1984},
      volume = {52},
      number = {17},
      pages = {1559--1562},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.52.1559}
    }
    
    Heckenkamp, C., Schäfers, F., Schönhense, G. & Heinzmann, U. Angular Dependence of the Spin-Polarization Transfer from Circularly Polarized Synchrotron Radiation onto Photoelectrons from Atomic Xe 5p^6 1984 Phys. Rev. Lett.
    Vol. 52(6), pp. 421- 
    article DOI  
    Abstract: The photoelectron emission from atomic xenon has been simultaneously resolved with respect to photon energy, photon (circular) polarization, photoelectron emission angle, electron kinetic energy, and spin-polarization components by use of synchrotron radiation of wavelengths between 48 and 90 nm from the new dedicated electron storage ring BESSY. The angular dependence of the spin polarization and the energy dependence of the dynamical spin parameters experimentally obtained show good agreement with theoretical predictions.
    BibTeX:
    @article{Heckenkamp1984,
      author = {Heckenkamp, Ch. and Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Angular Dependence of the Spin-Polarization Transfer from Circularly Polarized Synchrotron Radiation onto Photoelectrons from Atomic Xe 5p^6},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1984},
      volume = {52},
      number = {6},
      pages = {421--},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.52.421}
    }
    
    Schönhense, G., Schafers, F., Heckenkamp, C., Heinzmann, U. & Baig, M.A. Singlet-triplet mixing in Hg 6s photoionisation via autoionising transitions 1984 Journal of Physics B
    Vol. 17(22), pp. L771-L777 
    article DOI  
    Abstract: New experimental photoabsorption cross section and angle-resolved photoelectron spin polarisation data for mercury are presented. For the first three autoionisation resonances above the Hg 6s threshold an analysis is performed in terms of transition amplitudes to the singlet and triplet continua. These quantities reveal that photoionisation dynamics is largely influenced by a rather complicated spectral behaviour of the triplet matrix element, including three changes of sign. Results are compared with quantum defect differences and ratios of oscillator strengths from the discrete spectrum.
    BibTeX:
    @article{Schoenhense1984,
      author = {Schönhense, G. and Schafers, F. and Heckenkamp, Ch. and Heinzmann, U. and Baig, M. A.},
      title = {Singlet-triplet mixing in Hg 6s photoionisation via autoionising transitions},
      journal = {Journal of Physics B},
      year = {1984},
      volume = {17},
      number = {22},
      pages = {L771--L777},
      doi = {http://dx.doi.org/10.1088/0022-3700/17/22/002}
    }
    
    Schönhense, G. & Heinzmann, U. Evidence of strong interchannel coupling in Hg 5d photoionization by "experimental" transition matrix elements 1984 Phys. Rev. A
    Vol. 29(2), pp. 987-990 
    article DOI  
    Abstract: Experimental data of photoionization cross sections, photoelectron angular distributions, and photoelectron spin polarizations for mercury 5d have been used to determine dipole transition amplitudes and their relative phases. These basic quantities are compared with predictions of different theoretical models, revealing a strong interchannel interaction between the 5d→εp and 5d→εf channels, which was not directly visible in the measurable parameters.
    BibTeX:
    @article{Schoenhense1984a,
      author = {Schönhense, G. and Heinzmann, U.},
      title = {Evidence of strong interchannel coupling in Hg 5d photoionization by "experimental" transition matrix elements},
      journal = {Phys. Rev. A},
      publisher = {American Physical Society},
      year = {1984},
      volume = {29},
      number = {2},
      pages = {987--990},
      doi = {http://dx.doi.org/10.1103/PhysRevA.29.987}
    }
    
    Schönhense, G., Dzidzonou, V., Kaesdorf, S. & Heinzmann, U. Spin-Polarized Photoelectrons from Randomly Oriented Halogen Molecules by Unpolarized Radiation 1984 Phys. Rev. Lett.
    Vol. 52(10), pp. 811-814 
    article DOI  
    Abstract: Molecular photoelectrons have been observed to be spin polarized even if ejected from a beam of randomly oriented molecules by unpolarized radiation. The polarization and the asymmetry parameter β for Br2, I2, CH3Br, and CH3I are compared with general predictions of a nonrelativistic model. While all available data of the differential cross section agree with this prediction, spin-polarization results partly disagree, manifesting the influence of the spin-orbit interaction upon the phases of molecular continuum wave functions.
    BibTeX:
    @article{Schoenhense1984b,
      author = {Schönhense, G. and Dzidzonou, V. and Kaesdorf, S. and Heinzmann, U.},
      title = {Spin-Polarized Photoelectrons from Randomly Oriented Halogen Molecules by Unpolarized Radiation},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1984},
      volume = {52},
      number = {10},
      pages = {811--814},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.52.811}
    }
    
    Eyers, A., Heckenkamp, C., Schafers, F., Schonhense, G. & Heinzmann, U. A high flux normal incidence monochromator for circularly polarized synchrotron radiation 1983 Nuclear Instruments and Methods in Physics Research
    Vol. 208(1-3), pp. 303-305 
    article DOI  
    Abstract: Design and performance of a 6.3 m normal incidence UHV-monochromator (see fig. 1) of the Gillieson type for synchrotron radiation are described. The monochromator will be used for simultaneously spin polarization and emission angle-resolved photoelectron spectroscopy; it combines a high photon flux and a high degree of circular polarization of the monochromatized radiation with a moderate resolution.
    BibTeX:
    @article{Eyers1983,
      author = {Eyers, A. and Heckenkamp, Ch. and Schafers, F. and Schonhense, G. and Heinzmann, U.},
      title = {A high flux normal incidence monochromator for circularly polarized synchrotron radiation},
      journal = {Nuclear Instruments and Methods in Physics Research},
      year = {1983},
      volume = {208},
      number = {1-3},
      pages = {303--305},
      doi = {http://dx.doi.org/10.1016/0167-5087(83)91139-0}
    }
    
    Eyers, A., Kirschner, J., Müller, N., Oepen, H.P., Schäfers, F., Schönhense, G. & Heinzmann, U. Angle-, energy- and spin-resolved photoemission on nonmagnetic solids using circularly polarized Synchrotron radiation 1983 Annals of the Israel Physical Society
    Vol. 6, pp. 354 
    article DOI  
    Abstract: An angle-, energy-, and spin-resolved photoemission experiment has been performed for Pt(111) with the circularly polarized synchrotron radiation of the new German dedicated storage ring BESSY. The photoelectron polarization measured as function of the kinetic energy at different photon energies between 6.5 and 24 eV for normal incidence and normal emission shows a pronounced spectral variation up to ±55%. The electron intensities and polarizations observed allow a symmetry-resolved band characterization of Pt in the Γ-L direction.
    BibTeX:
    @article{Eyers1983a,
      author = {Eyers, A. and Kirschner, J. and Müller, N. and Oepen, H. P. and Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Angle-, energy- and spin-resolved photoemission on nonmagnetic solids using circularly polarized Synchrotron radiation},
      journal = {Annals of the Israel Physical Society},
      year = {1983},
      volume = {6},
      pages = {354},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.52.1559}
    }
    
    Heckenkamp, C., Schäfers, F., Schönhense, G. & Heinzmann, U. First angle-resolved measurements of spin polarization transfer (Fano effect) from circularly polarized vuv radiation onto photoelectrons at rare gas atoms 1983 Annals of the Israel Physical Society
    Vol. 6, pp. 115  
    article  
    BibTeX:
    @article{Heckenkamp1983,
      author = {Heckenkamp, Ch. and Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {First angle-resolved measurements of spin polarization transfer (Fano effect) from circularly polarized vuv radiation onto photoelectrons at rare gas atoms},
      journal = {Annals of the Israel Physical Society},
      year = {1983},
      volume = {6},
      pages = {115 }
    }
    
    Kaesdorf, S., Schönhense, G. & Heinzmann, U. Angle- and spin-resolved photoelectron spectroscopy on some halogen molecules 1983 Annals of the Israel Physical Society
    Vol. 6, pp. 179 
    article  
    BibTeX:
    @article{Kaesdorf1983,
      author = {Kaesdorf, S. and Schönhense, G. and Heinzmann, U.},
      title = {Angle- and spin-resolved photoelectron spectroscopy on some halogen molecules},
      journal = {Annals of the Israel Physical Society},
      year = {1983},
      volume = {6},
      pages = {179}
    }
    
    Rinneberg, H., Neukammer, J., Majewski, U. & Schönhense, G. High-Resolution Electron Spectroscopy of Laser-Excited Ba Rydberg Atoms 1983 Phys. Rev. Lett.
    Vol. 51(17), pp. 1546-1549 
    article DOI  
    Abstract: The ionization of 6sns 1S0 Rydberg states of 138Ba has been investigated by high-resolution electron spectroscopy. The Rydberg states were excited by two cw dye lasers via the 6s6p 1P1 level. The electron spectra show rich structure between 0.025 and 3 eV, largely attributable to collisional (Penning) ionization, photoionization, and autoionizing transitions. The first process might be interpreted as superelastic scattering of the Rydberg electron by optically pumped Ba(6s6p 1P1) or Ba(6s5d1D2) atoms.
    BibTeX:
    @article{Rinneberg1983,
      author = {Rinneberg, H. and Neukammer, J. and Majewski, U. and Schönhense, G.},
      title = {High-Resolution Electron Spectroscopy of Laser-Excited Ba Rydberg Atoms},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1983},
      volume = {51},
      number = {17},
      pages = {1546--1549},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.51.1546}
    }
    
    Schäfers, F., Schönhense, G. & Heinzmann, U. Analysis of Ar 3p6 and Kr 4p6 photoionization from photoelectron-spin-polarization data 1983 Phys. Rev. A
    Vol. 28(2), pp. 802-814 
    article DOI  
    Abstract: Experimental data of the cross section and of the asymmetry parameter β in combination with photoelectron-spin-polarization results of Ar 3p6 and Kr 4p6 subshell photoionization were used to determine the bound-free matrix elements and phase-shift differences of the continuum wave functions in a photon-energy region from threshold to 41 eV. The paper includes a discussion of the first autoionization region between the 2P3 / 2 and 2P1 / 2 thresholds in the framework of the angular-momentum-transfer formalism. The experimental results are compared with semiempirical and ab initio calculations with the use of line positions and oscillator strengths in the discrete part extrapolated to the continuum in application of the multichannel quantum-defect theory.
    BibTeX:
    @article{Schaefers1983,
      author = {Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Analysis of Ar 3p6 and Kr 4p6 photoionization from photoelectron-spin-polarization data},
      journal = {Phys. Rev. A},
      publisher = {American Physical Society},
      year = {1983},
      volume = {28},
      number = {2},
      pages = {802--814},
      doi = {http://dx.doi.org/10.1103/PhysRevA.28.802}
    }
    
    Schönhense, G. Magnetic-field-free vapor furnace for photoelectron spectroscopy. I. Temperatures up to 900 K 1983 Review of Scientific Instruments
    Vol. 54, pp. 419-421 
    article DOI  
    Abstract: A vapor furnace producing stable atomic and molecular beams for photoionization experiments is described. During operation the furnace causes no detectable magnetic stray field because it is heated by a stream of hot air. Thus angle- and energy-resolved measurements of photoelectron spin polarization could be done at a kinetic energy as low as 0.5 eV. The high temporal stability of the target beam is demonstrated by means of an angular distribution measurement with mercury atoms.
    BibTeX:
    @article{Schoenhense1983,
      author = {Schönhense, G.},
      title = {Magnetic-field-free vapor furnace for photoelectron spectroscopy. I. Temperatures up to 900 K},
      journal = {Review of Scientific Instruments},
      year = {1983},
      volume = {54},
      pages = {419-421},
      doi = {http://dx.doi.org/10.1063/1.1137409}
    }
    
    Schönhense, G. & Heinzmann, U. A capillary discharge tube for the production of intense VUV resonance radiation 1983 Journal of Physics E
    Vol. 16(1), pp. 74-82 
    article DOI  
    Abstract: Design and operational characteristics of a line source with very high intensity in the vacuum UV are described. The source generates rare-gas resonance radiation in a low-pressure, cold-cathode, DC glow discharge up to 200 mA. The windowless lamp is differentially pumped and can be installed inside a vacuum chamber. During operation it is water cooled and can be mildly baked because it contains metal seals only. In a light beam of 2.5 mm diameter the photon flux for the strongest HeI and NeI emission line has been measured to be nearly 1013s-1and one order of magnitude less for the strongest HeII, NeII and ArI lines. The photon intensities obtained are compared with values from the literature. The lamp has been used to investigate atomic and molecular photoionisation simultaneously resolved with respect to photon and electron energy, electron emission angle, and spin. To show the performance, angular-distribution results of photoelectron intensities for nitrogen molecules (X2 Sigma g+, A2 Pi u, B2 Sigma u+) at 58.43 nm are presented.
    BibTeX:
    @article{Schoenhense1983a,
      author = {Schönhense, G. and Heinzmann, U.},
      title = {A capillary discharge tube for the production of intense VUV resonance radiation},
      journal = {Journal of Physics E},
      year = {1983},
      volume = {16},
      number = {1},
      pages = {74--82},
      doi = {http://dx.doi.org/10.1088/0022-3735/16/1/015}
    }
    
    Schäfers, F., Schönhense, G. & Heinzmann, U. Analysis of autoionization resonance in the Hg 6s2-photoionization by measurements of photoelectron polarization 1982 Z. Physik A
    Vol. 304, pp. 30441 
    article  
    BibTeX:
    @article{Schaefers1982,
      author = {Schäfers, F. and Schönhense, G. and Heinzmann, U.},
      title = {Analysis of autoionization resonance in the Hg 6s2-photoionization by measurements of photoelectron polarization},
      journal = {Z. Physik A},
      year = {1982},
      volume = { 304},
      pages = {30441}
    }
    
    Schönhense, G., Schäfers, F., Heinzmann, U. & Kessler, J. Angle- and spin-resolved photoelectron spectroscopy of the Hg 5d10 subshell 1982 Z. Physik A
    Vol. 304, pp. 31 
    article  
    BibTeX:
    @article{Schoenhense1982,
      author = {Schönhense, G. and Schäfers, F. and Heinzmann, U. and Kessler, J.},
      title = {Angle- and spin-resolved photoelectron spectroscopy of the Hg 5d10 subshell},
      journal = {Z. Physik A},
      year = {1982},
      volume = {304},
      pages = {31}
    }
    
    Schönhense, G., Heinzmann, U., Kessler, J. & Cherepkov, N.A. Photoelectron Polarization in Hg 6s2 Subshell Ionization with Unpolarized Light: New Aspect of the Fano Effect 1982 Phys. Rev. Lett.
    Vol. 48(9), pp. 603-606 
    article DOI  
    Abstract: Experimental evidence is presented for the effect of photoionization of ns2 atomic subshells with unpolarized radiation that leads to highly polarized photoelectrons in angular-resolved measurements. Like the Fano effect, the observed phenomenon is caused by spin-orbit interaction in the continuous spectrum. The spin polarization essentially depends on the phase-shift difference between the εp1 / 2 and εp3 / 2 continua.
    BibTeX:
    @article{Schoenhense1982a,
      author = {Schönhense, G. and Heinzmann, U. and Kessler, J. and Cherepkov, N. A.},
      title = {Photoelectron Polarization in Hg 6s2 Subshell Ionization with Unpolarized Light: New Aspect of the Fano Effect},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {1982},
      volume = {48},
      number = {9},
      pages = {603--606},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.48.603}
    }
    
    Heckenkamp, C., Heinzmann, U., Schönhense, G., Burgess, D.D., Thorne, A.P. & Wheaton, J.E.G. A laser-generated plasma as a source of VUV continuum radiation for photoelectronic spectroscopy 1981 Journal of Physics D
    Vol. 14(12), pp. L203-L206 
    article DOI  
    Abstract: The feasibility of using laser-generated plasmas as VUV continuum sources for photoelectron spectroscopy has been demonstrated by measuring the spectral intensity distribution of the VUV continuum in the wavelength region from 79 to 43 nm by energy analysis of the photoelectrons ejected from argon atoms. The maximum photon flux obtained after reflection at a gold-coated spherical mirror was of the order of 1011 photons nm-1 per pulse at 50 nm for a laser energy of 830 mJ. The results show a shift of the emission maximum to lower wavelengths with increasing laser energy.
    BibTeX:
    @article{Heckenkamp1981,
      author = {Heckenkamp, C. and Heinzmann, U. and Schönhense, G. and Burgess, D. D. and Thorne, A. P. and Wheaton, J. E. G.},
      title = {A laser-generated plasma as a source of VUV continuum radiation for photoelectronic spectroscopy},
      journal = {Journal of Physics D},
      year = {1981},
      volume = {14},
      number = {12},
      pages = {L203--L206},
      doi = {http://dx.doi.org/10.1088/0022-3727/14/12/002}
    }
    
    Heinzmann, U., Osterheld, B., Schafers, F. & Schonhense, G. Spin-polarised photoelectrons produced from CH3Br molecules by unpolarised and circularly polarised VUV radiation 1981 Journal of Physics B
    Vol. 14(3), pp. L79-L84 
    article DOI  
    Abstract: It has been experimentally verified for CH3Br that spin-polarised photoelectrons can be ejected from unoriented molecules if the radiation is circularly polarised or even unpolarised. The polarisation values and the experimental data of the asymmetry parameter beta are discussed by use of Cherenkov's formulae (1981).
    BibTeX:
    @article{Heinzmann1981,
      author = {Heinzmann, U. and Osterheld, B. and Schafers, F. and Schonhense, G.},
      title = {Spin-polarised photoelectrons produced from CH3Br molecules by unpolarised and circularly polarised VUV radiation},
      journal = {Journal of Physics B},
      year = {1981},
      volume = {14},
      number = {3},
      pages = {L79--L84},
      doi = {http://dx.doi.org/10.1088/0022-3700/14/3/009}
    }
    
    Schönhense, G. Photoelectron angular distribution for mercury 5d and cadmium 4d 1981 Journal of Physics B
    Vol. 14(5), pp. L187-L192 
    article DOI  
    Abstract: The asymmetry parameter beta for the process Hg(5d106s2)1S0+hv to Hg+(5d96s2)2D32,5/2/+e- for Cd4d5s analogously) has been measured at rare-gas resonance wavelengths between 73.59 and 30.38 nm. The data for Cd disagree with a previous measurement available in the literature. The results are compared with relativistic and non-relativistic calculations of several authors. The experimental beta values for Hg5d give evidence of relativistic effects.
    BibTeX:
    @article{Schoenhense1981,
      author = {Schönhense, G.},
      title = {Photoelectron angular distribution for mercury 5d and cadmium 4d},
      journal = {Journal of Physics B},
      year = {1981},
      volume = {14},
      number = {5},
      pages = {L187--L192},
      doi = {http://dx.doi.org/10.1088/0022-3700/14/5/006}
    }
    
    Heinzmann, U., Schönhense, G. & Kessler, J. Wavelength dependence of polarisation of photoelectrons ejected by unpolarised VUV radiation from argon and krypton atoms 1980 Journal of Physics B
    Vol. 13(5), pp. L153-L156 
    article DOI  
    Abstract: The spin polarisation of the photoelectrons emitted by argon and krypton atoms exposed to unpolarised VUV radiation has been measured at rate-gas resonance wavelengths in the energy range from the threshold up to 41 eV. Comparison of the wavelength dependence of the measured polarisation with theoretical results shows good agreement.
    BibTeX:
    @article{Heinzmann1980,
      author = {Heinzmann, U. and Schönhense, G. and Kessler, J.},
      title = {Wavelength dependence of polarisation of photoelectrons ejected by unpolarised VUV radiation from argon and krypton atoms},
      journal = {Journal of Physics B},
      year = {1980},
      volume = {13},
      number = {5},
      pages = {L153--L156},
      doi = {http://dx.doi.org/10.1088/0022-3700/13/5/006}
    }
    
    Heinzmann, U., Schönhense, G. & Wolcke, A. Spin polarized photoelectrons from unpolarized lead atoms exposed to unpolarized radiation 1980 Coherence and correlation in atomic collisions, pp. 607 ff  incollection  
    BibTeX:
    @incollection{Heinzmann1980a,
      author = {Heinzmann, U. and Schönhense, G. and Wolcke, A.},
      title = {Spin polarized photoelectrons from unpolarized lead atoms exposed to unpolarized radiation},
      booktitle = {Coherence and correlation in atomic collisions},
      publisher = {Plenum Press, New York und London},
      year = {1980},
      pages = {607 ff}
    }
    
    Schönhense, G. Angular Dependence of the Polarization of Photoelectrons Ejected by Plane-Polarized Radiation from Argon and Xenon Atoms 1980 Physical Review Letters
    Vol. 44(10), pp. 640-643 
    article DOI  
    Abstract: The photoelectrons produced by ionization of argon and xenon atoms with linearly polarized vacuum-ultraviolet radiation of the helium resonance wavelength 58.43 nm have been analyzed simultaneously as to their energy, angle of emission, and spin. Degrees of spin polarization up to 0.5 have been found. The results verify the theoretically predicted angular dependence of the photoelectron polarization. The asymmetry parameter β describing the angular distribution of the cross section is determined via electron intensity and polarization measurements.
    BibTeX:
    @article{Schoenhense1980,
      author = {Schönhense, G.},
      title = {Angular Dependence of the Polarization of Photoelectrons Ejected by Plane-Polarized Radiation from Argon and Xenon Atoms},
      journal = {Physical Review Letters},
      publisher = {APS},
      year = {1980},
      volume = {44},
      number = {10},
      pages = {640--643},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.44.640}
    }
    
    Heinzmann, U., Schönhense, G. & Kessler, J. Polarization of Photoelectrons Ejected by Unpolarized Light from Xenon Atoms 1979 Physical Review Letters
    Vol. 42(24), pp. 1603-1605 
    article DOI  
    Abstract: The theoretical prediction that polarized photoelectrons can be ejected from unpolarized atoms by unpolarized radiation has been experimentally verified for xenon atoms. The wavelength dependence of the polarization has been measured and compared with theoretical results at helium and neon resonance wavelengths between 74.4 and 46.1 nm.
    BibTeX:
    @article{Heinzmann1979,
      author = {Heinzmann, U. and Schönhense, G. and Kessler, J.},
      title = {Polarization of Photoelectrons Ejected by Unpolarized Light from Xenon Atoms},
      journal = {Physical Review Letters},
      publisher = {American Physical Society},
      year = {1979},
      volume = {42},
      number = {24},
      pages = {1603--1605},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.42.1603}
    }
    

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