Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 46: Adsorption VI
O 46.5: Vortrag
Freitag, 31. März 2006, 12:15–12:30, TRE Phys
STRUCTURE AND PROPERTIES OF K-O COADSORBATE PHASES ON RH(110): CHEMICAL PATTERNS AND LOW PRESSURE PATHWAY TO SURFACE OXIDE FORMATION — •Sebastian Günther1, Friedrich Esch2, Giovanni Comelli2, and Maya Kiskinova3 — 1Department Chemie, Ludwig-Maximilians Universität München, Butenandtstr. 11 E, 81377 München, Germany — 2Laboratorio TASC-INFM, Area Science Park, 34012 Trieste, Italy — 3Sincrotrone Trieste, Area Science Park, 34012 Trieste, Italy
The present study of K-O coadsorbate system on Rh(110) has been inspired by the peculiar chemical wave patterns observed during the H2 + O2 reaction on the K-covered Rh(110) surface. Using Low energy electron diffraction (LEED), Scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) we found that coadsorption of O and K at T > 450 K leads to a variety of ordered phases, all of them involving missing-row reconstructions of the substrate. The building blocks of these surface structures were determined. The massive restructuring of the surface at high K coverage is followed by growth of a surface oxide phase, which cannot be formed on a K-free surface under UHV conditions. The surface composition and activity of the coadsorbed phases were characterized by XPS, which revealed that although K adatoms promote the O2 adsorption and oxidation of the substrate, they act as deactivators for the H2 + O2 reaction.