Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 17: Zeitaufgelöste Spektroskopie I

O 17.3: Vortrag

Dienstag, 25. März 2003, 11:45–12:00, FOE/ORG

Modification of adsorbate substrate coupling by means of metallic-thin-film overlayers — •Marlies Wessendorf, Carsten Wiemann, Michael Bauer, and Martin Aeschlimann — Department of Physics, Kaiserslautern University of Technology, 67663 Kaiserslautern

The understanding of the dynamics of excited electrons on adsorbate covered surfaces is a key point for the description of a variety of surface reactions and in particular of photon and electron-stimulated reactions. The efficiency of these reaction mechanisms depends in a crucial way on the lifetime of intermediate electronic states. Recently, it has been demonstrated that adsorbed alkali atoms on noble metals are an ideal model system to study the dynamics of charge transfer processes between surface and chemisorbed adsorbates [1]. In A theoretical work, Borisov et al showed that the substrate band structure is the most important parameter for the specific relaxation dynamics of the excited alkali state [2]. In this paper we report our recent results obtained for Cs-absorption on Ag/Cu(111) overlayer systems by means of time-resolved two-photon photoemission. The variation of the Ag-layer thickness allows a defined control of the substrate band structure and, hence, the lifetime of the investigated intermediate adsorbed state. [1] M. Bauer et al, Phys. Rev. B 60 (1999) 5016 [2] A.G. Borisov et al, Phys.Rev.Lett. 86, 488 (2001)