Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 68: Metal Substrates: Adsorption V

O 68.4: Vortrag

Freitag, 30. März 2007, 11:00–11:15, H39

Adsorption of CO on stepped Rh(553) — •Hans Peter Koch, Priyanka Singnurkar, and Robert Schennach — Graz University of Technology, Institute of Solid State Physics, Graz, Austria

The adsorption of CO on stepped surfaces has so far only been investigated on a limited number of systems. On Pt (112) and (335) for example distinct desorption peaks for CO from the steps and from the terraces were reported [J. Xu, J. Yates Surf. Sci. 327(1995)193]. In this work we show that CO adsorption on the stepped Rh(553) surface behaves surprisingly different. Thermal desorption spectroscopy (TDS) does not show a peak that can be attributed to CO adsorbed on the steps. Angle resolved thermal desorption data show a simple cosine distribution, as would be expected from a (111) surface. Nevertheless, reflection absorption infra red spectroscopy (RAIRS) shows vibrational features that can be attributed to CO molecules adsorbed on the steps. Apparently, the difference in the desorption energy of CO bound on terraces and on steps is not very different according to the TPD results. However, the binding of the CO molecules on the steps and terraces is different enough to show unique vibrational features in RAIRS. The experimental results will be discussed in the light of recent density functional theory calculations.