Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 62: Metal Substrates: Adsorption of Inorganic Molecules

O 62.2: Talk

Thursday, February 28, 2008, 09:45–10:00, MA 042

Quantum size effects on the adsorption of rare gases on Ag monolayer covered noble metal surfaces — •Frank Forster, Andreas Nuber, Hendrik Bentmann, Johannes Ziroff, and Friedrich Reinert — Universtät Würzburg, Experimentelle Physik II, 97074 Würzburg, Germany

In the recent past it has been demonstrated that Shockley states on (111) surfaces of Cu, Ag, and Au are a sensitive probe for interactions between surfaces and adsorbates. Their significant change in binding energy, band mass and spin-orbit coupling allows an access to the comprehension of adsorption mechanisms like physisorption. On the example of Xe monolayers on noble metal surfaces we show vice versa that the Shockley states influence the adsorption dynamics of rare gas atoms. For that purpose we present real-time and high resolution ARPES investigations on Xe adsorption on Cu(111) and Au(111) substrates with Shockley states modified by a pre-adsorption of layer-by-layer grown Ag-films of various thickness. In the case of Xe on Ag/Cu(111) we found that the rare gas prefers the adsorption on the thickest Ag film to the disadvantage of thinner layers or the clean substrate. A similar behaviour could be observed for Ag/Au(111) with the exception of a single Ag layer, which is always unfavoured for Xe coverage. Within a simplified model, the local DOS of the Shockley state at the modified surfaces are compared to the obtained ARPES results.