Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Metal substrates: Adsorption of inorganic molecules
O 64.6: Vortrag
Freitag, 27. März 2009, 12:30–12:45, SCH A215
Monte-Carlo lattice gas simulation of adsorption and desorption at disordered surface alloys — •Markus Mauksch1, Andreas Bergbreiter1, Harry E. Hoster1, Yoshihiro Gohda2, Axel Groß2, and R. Jürgen Behm1 — 1Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm — 2Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm
The atom distribution in disordered surface alloys like PtRu/Ru(0001)or PdAg/Pd(111) is known from STM imaging with chemical contrast. The interaction of model adsorbates like Had or CO with many of these surfaces were probed by thermal desorption and infrared spectroscopy [1]. Based on experimentally determined atom distributions in the surface alloys, we will model the adsorption properties of selected systems by lattice gas Monte-Carlo simulations including (i) site-specific molecule-substrate, (ii) molecule-molecule interaction energies and (iii) site-specific vibrational entropy [2]. Where available, molecule-substrate interactions are derived from DFT results, in other cases they are fitted to experimental data. The molecule-molecule interactions and site specific entropies are assumed to be close to those for Pt(111) [2] and Ru(0001) [3].
[1] H. Rauscher et al., Surf.Sci. 601 (2007) 4608.
J.-S. McEwen et al., Surf.Sci. 545 (2003) 47.
J.-S. McEwen et al., J.Chem.Phys. 126 (2007) 094701.