Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.47: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
Dependence of ultrafast charge transfer on orbital overlap — •Martin Deppe1, Alexander Föhlisch1, Franz Hennies2, Mitsuru Nagasono1, Martin Beye1, and Wilfried Wurth1 — 1Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany — 2MAX-lab, Lund University, Ole Römers väg 1, SE-22100 Lund, Sweden
We have determined the dependence of the charge transfer time τCT on orbital overlap for a chemisorbed S monolayer on a Ru(0001) single crystal substrate by core hole clock spectroscopy. By changing the polarization of the synchrotron light relative to the surface plane S 3p orbitals with different spatial orientations can be selected.
We show that the process is much faster for orbitals with their main symmetry axis perpendicular to the substrate surface (out-of-plane) than for those oriented parallel to the surface plane (in-plane). In both cases the transfer occurs on a timescale faster than 1 fs; in out-of-plane geometry we find τCT=0.18 ± 0.04 fs, while the in-plane case yields τCT=0.84 ± 0.36 fs, both for photon energies directly above the autoionization resonance. This is the direct consequence of the fact that charge transfer is governed by the orbital overlap at the different atomic sites. To achieve the necessary temporal resolution, ultrafast Coster-Kronig autoionization decays are used as internal reference clocks.