Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 62: Metal Substrates: Adsorption of Inorganic Molecules

O 62.6: Talk

Thursday, February 28, 2008, 10:45–11:00, MA 042

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

Carbon monoxide is a widely used probe molecule in surface science. In addition, it is an important reactant and intermediate in several catalytic reactions (e.g. oxidation of carbon monoxide to carbon dioxide in automotive catalysts), making the adsorption and reaction of carbon monoxide a thoroughly investigated system on many different metal surfaces. In the work presented here, the adsorption and desorption of carbon monoxide on Ni decorated steps on Rh(553) has been studied using reflection absorption infra red spectroscopy (RAIRS) and thermal desorption spectrometry (TDS). Previous scanning tunneling microscopy (STM) experiments have shown, that the Rh(553) surface has rather stable mono atomic steps. The steps are (111) oriented and the (111) terraces are 4 atomic rows wide, as can be predicted from the crystal structure. The steps of the Rh(553) surface can be decorated by evaporating about 0.2 mono layer Ni under ultra high vacuum conditions and at a substrate temperature of 150°C, leading to one to two atoms wide Ni wires running along the steps of the Rh(553) substrate, according to STM data. No carbon monoxide dissociation is found when the steps are decorated with Ni. TDS results and RAIRS results on the Ni decorated surface are discussed with respect to the results obtained with the clean Rh(553) surface.