Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.80: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
Photoemission study of occupied and unoccupied states on Si(553)-Au — •Stefan Regensburger1, Kerstin Biedermann1, Thomas Fauster1, Franz J. Himpsel2, and Steven C. Erwin3 — 1Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany — 2Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA — 3Center for Computational Materials Science, Naval Research Laboratory, Washington, DC 20375, USA
Atomic gold chains on vicinal Si(111) surfaces serve as model system for one-dimensional electronic states. For the characterization of the electronic states near the Γ-point we used angle- and time-resolved two-photon photoemission with photon energies of 1.55 eV and 4.65 eV, as well as photoemission with 6.2 eV photon energy. Information about the symmetry of the electronic states was obtained from the polarization dependence of the spectra.
In addition to bulk transitions, the Rasha-split gold bands [1] and the n=1 image-potential resonance we find two states related to the step-edge atoms. We observe an unoccupied state with even symmetry in the bulk band gap of silicon with a lifetime of τ=125 fs. It is assigned to the spin-polarized step-edge atoms predicted by theory [2]. An occupied state located 0.42 eV below the Fermi level corresponds to non-magnetic step-edge atoms coupled in pairs.
[1] Crain, J. N. et al., Phys. Rev. B 69, 125401 (2004)
[2] Erwin, S. C. and Himpsel, F. J., Nat. Commun. 1, 58 (2010)