Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Surface chemical reactions II
O 58.3: Vortrag
Mittwoch, 24. März 2010, 15:30–15:45, H42
Oxidation of CO over RuO2(110): a Reflection-Absorption IR Spectroscopy study — •Attila Farkas, Georg Christoph Mellau, and Herbert Over — Physikalisch-Chemisches Institut, Justus-Liebig-Universitaet Giessen, Germany
Kinetic Monte Carlo (kMC) simulations [1,2] of heterogeneously catalyzed reactions present a powerful potential for unraveling the reaction mechanism at molecular level. The spatial distribution of the reactants at the catalyst surface can be computed even for pressures which fall outside the scope of standard ultra-high vacuum (UHV) experimental methods.
Reflection-Absorption IR Spectroscopy (RAIRS) has been used to study the oxidation of CO over the model catalyst RuO2(110), under experimental conditions entailing a variation by four orders of magnitude in the reactant pressure (from 10−7 to 10−3 mbar) [3]. A careful analysis of high pressure RAIRS spectra has led to a rather complete picture of the steady state at the catalyst surface under reaction conditions at 350 K. While an elementary kMC approach of the type of Ref. [1] has been found satisfactory in accounting for the experimental results, more elaborated first principles (ab initio) kMC tretments [3] have failed to do so. The sources of discrepancy between experiment and first principles theory will be critically discussed.
1. R.M. Ziff, E. Gulari, Y. Barshad, Phys. Rev. Lett., 56, 2553 (1986)
2. K. Reuter, M. Scheffler, Phys. Rev. B, 73, 045433, (2006)
3. A. Farkas, G.Ch. Mellau, H. Over, J. Phys. Chem. C,113, 14341-14355, (2009)