Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 50: Time-resolved spectroscopy II
O 50.6: Vortrag
Freitag, 31. März 2006, 12:30–12:45, WIL C207
Ultrafast decay dynamics of a photoexcited adsorbate in interaction with a two-dimensional metallic substrate — •M. Bauer1, M. Wessendorf1, S. Matthias1, J. Lange1, M. Aeschlimann1, V.M. Silkin2, A.G. Borisov3, P.M. Echenique2,4, J.P. Gauyacq3, and E.V. Chulkov2,4 — 1Department of Physics, University of Kaiserslautern, 67663 Kaiserslautern — 2Donostia International Physics Center, San Sebastián, 20018, Spain — 3Laboratoire des Collisions Atomiques et Moléculares, Université Paris-Sud, 91405 Orsay Cedex, France — 4Departamento de Física de Materiales and Centro Mixto, Facultad de Química, San Sebastián, Spain
The lifetime of adsorbate resonances is known to play a key role in the course of many photoinduced surface reactions. Control of the resonance lifetime would, therefore, be a means of manipulating surface chemical processes. In this paper we report on the tuning of a resonance lifetime by interaction of an adsorbate with epitaxically grown thin metal films at varying thickness. For the model system Cs/Ag/Cu(111) we observe that the lifetime of the cesium 6s resonance depends critically on silver film thickness and varies by a factor of three in the thickness regime between 1 and 7 ML. Our results are in qualitative good agreement with theoretical predictions. Quantitative discrepancies are related to structural (stress induced) modifications of the silver film and the copper substrate. Our result is a striking example for a fundamental property of adsorbate-surface interaction relevant for surface chemical processes modified by the dimensionality of the substrate.