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O: Oberflächenphysik

O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)

O 15.1: Poster

Freitag, 4. März 2005, 17:00–20:00, Poster TU D

Compression of submonolayer goldfilms by CO adsorption on a Re( 1010 ) surface — •C. Pauls and K. Christmann — Inst. f. Chemie, FU Berlin, Takustr. 3, 14195 Berlin

We have studied the adsorption of carbon monoxide on the clean and partially gold-covered Re(10-10) surface by means of LEED, thermal desorption (TPD) and work function change ( Δ Φ ) measurements. On the Re(10-10) surface, increasing coverages of Au produce a variety of (1xn) LEED superstructures in the submonolayer regime (n = 3, 4, 5, 6), until a pseudomorphic (1x1) phase is formed at a complete Au monolayer. This phase has been subjected to a quantitative LEED analysis and clearly reveals a continuation of the Re lattice by a double layer of Au atoms in the ’A’ termination of the Re(10-10) surface. Still larger Au coverages lead to a (1x8) LEED phase which is surprisingly stable in the multilayer regime. Interesting effects become apparent, if CO is adsorbed into the submonolayer Au phases: Apparently, CO is able to compress the rows of Au atoms in [0001] direction, i.e., perpendicular to the troughs, since the low-coverage (1x3) and (1x4) Au phases undergo transitions to the (1x4) and (1x5) phases, respectively, in the presence of coadsorbing CO. So far, similar effects have only been reported for coadsorption of oxygen and gold on a ruthenium (10-10) surface [1].

[1] S. Poulston, M. Tikhov, and R.M. Lambert, Langmuir 13 (1997) 5356