Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 45: Zeitaufgelöste Spektroskopie II

O 45.4: Vortrag

Freitag, 12. März 2004, 12:00–12:15, H39

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

We investigated the lifetime of Caesium atoms adsorbed on thin Ag film overlayers on Cu(111) by means of time-resolved two-photon photoemission spectroscopy (TR-2PPE). Direct and indirect interaction with the silver overlayer gives rise to significant changes in the lifetime of the adsorbate excitation. The electronic band structure of the Ag / Cu(111) substrate can be controlled by variation of the Ag interface layer thickness in a distinct way. Tuning the layer thickness allows to adjust the excited states lifetimes of the adsorbate and, hence, gives the possibility to control specific properties of chemical surface reactions such as efficiency and reaction channel. In this paper we report our recent results for Cs adsorption on Ag / Cu(111) overlayer systems. The experimental results contain information about the dynamics of the decay of the investigated intermediate adsorbed state as well as of the motion of the alkali atoms perpendicular to the surface after excitation.