Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 56: Metal substrates: Epitaxy, growth and adsorbates

O 56.6: Talk

Thursday, March 26, 2009, 16:15–16:30, SCH A316

Floating of PtRu and PdRu surface alloys on Ru(0001) studied by STM and AES — •Andreas Bergbreiter, Harry E. Hoster, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm

According to previous studies by scanning tunnelling microscopy (STM) with chemical contrast and Auger electron spectroscopy (AES), deposition of submonolayer Pt (Pd) on Ru(0001) and subsequent annealing to T = 1300 K (1150 K) results in atomically smooth and laterally equilibrated PtRu (PdRu) surface alloys on Ru(0001) confined to the outermost layer [1]. To verify whether or not these surface alloys reflect local equilibrium, the prepared alloys were deliberately buried by > 1 ML of vapor deposited Ru. After surface analysis by STM and AES, these samples were again annealed to the respective surface alloy formation temperature. Both STM and AES confirm that the initially formed surface alloy is recovered by this final annealing step, i.e., both types of surface alloys exhibit a surfactant-like floating behavior. We discuss, in how far this behaviour depends on the transport mechanism involved in the surface alloy formation process, and for which types of surface alloys a similar inherent stability is to be expected.
[1] H.E. Hoster et al., Phys.Chem.Chem.Phys. 10 (2008) 3812.