Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)
O 27.121: Poster
Dienstag, 24. März 2009, 18:30–21:00, P2
Momentum-Resolved Dynamics of Electrons in Image-Potential States on Ag(111) and Cu(111) — •A. Damm1, K. Schubert1, S.V. Eremeev2, A.G. Borisov3, E.V. Chulkov4, P.M. Echenique4, J. Güdde1, and U. Höfer1 — 1Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, D-35032 Marburg, Germany — 2Institute of Strength Physics and Material Science, 634021 Tomsk, Russia — 3Laboratoire des Collisions Atomiques et Moléculaires, Université Paris-Sud, 91405 Orsay Cedex, France — 4Donostia International Physics Center, 20018 San Sebastián, Basque Country, Spain
We report on the momentum-dependence of the decay rate of electrons in image-potential states on Ag(111) and Cu(111) investigated by time- and angle-resolved two-photon photoemission (2PPE). On these surfaces, the n=1 image-potential state is located within the projected bulk band gap only close to the Γ-point, whereas it becomes degenerated with a projected bulk band at k∥≈ 0.2 Å-1. This offers the opportunity to investigate differences in the electron dynamics of surface gap states and resonances within one model system. While the lifetime of gap states is dominated by inelastic decay due to electron-hole-pair excitations, an additional decay channel due to elastic charge transfer into the bulk exists for resonances. We observe a continuous increase of the decay rate with k∥ on both surfaces without a sudden change at the band edge. We compare these results with a theoretical description based on many-body calculations for the inelastic decay and a wave-packet propagation method for the elastic charge transfer.