Regensburg 2002 – wissenschaftliches Programm
O 32.1: Vortrag
Donnerstag, 14. März 2002, 15:30–15:45, H43
Kinetic Monte Carlo Simulation of adsorbate-assisted adsorption and effect of adsorption temperature — •Jörg Stephan1 and Uwe Burghaus2 — 1Institute of Physics, University of Potsdam, 14415 Potsdam, Germany — 2Department of Chemistry, PC1, Ruhr-University of Bochum, 44801 Bochum, Germany
Adsorbate-assisted adsorption has frequently been observed for prototype adsorbates on metal and metal oxide surfaces. We recently presented a steady-state Monte Carlo (sMC) version of the modified Kisliuk model to explain the energy dependence and the effect of defects, as observed for CO/ZnO and CO/Cu(110). Although sMC-Simulations can lead to a better understanding of the microscopic scenario, the definition of the precursor dynamics was over-simplifying and the influence of adsorption temperature on the coverage dependence of S(Theta) could not be studied. We therefore present an improved time-dependent Monte Carlo simulation scheme (kMC) which can account for both, impact energy as well as temperature dependence of S(THeta). Additionally, more realistic rules defining the precursor dynamics are applied. Our kMC simulation scheme is tested for different adsorption scenarios, such as the cross-over from Kisliuk to Langmuir dynamics and adsorbate-assisted adsorption. We present energy and temperature dependent simulations and compare the results with experimental data for CO adsorption on the polar ZnO surfaces. The polar surfaces of ZnO are a perfect test system for the algorithm which is mainly based on the differences in the mass-mismatch of the adsorbate (CO) and the surface atoms (O or Zn).