AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS1+MC-ThM

Paper SS1+MC-ThM5
Monte Carlo Simulation of Initial Al(111) Oxidation

Thursday, October 5, 2000, 9:40 am, Room 208

Session: Oxide Applications and Oxidation
Presenter: D.E. Oner, Chalmers University of Technology, Sweden
Authors: D.E. Oner, Chalmers University of Technology, Sweden
R. Chakarova, Chalmers University of Technology, Sweden
I. Zori@aa c@, Chalmers University of Technology, Sweden
B. Kasemo, Chalmers University of Technology, Sweden
Correspondent: Click to Email
In this work a Monte Carlo simulation technique is applied, exploring the influence of several models for O@sub 2@ dissociation on the initial Al(111) oxidation. The primary experimental data motivating this are the STM studies by Brune et al. (J. Chem. Phys. 99 (1993) 2128). The simulations are performed to gain more insight into the kinetics of the oxidation process. The Monte Carlo simulation is based on the lattice-gas approach using the Metropolis algorithm. The simulations assume alternatively "normal" dissociation (deposition of O atoms at adjacent surface sites), hot dimer dissociation (widely separated O atoms due to hot dissociation fragments) or abstraction (one of the separating O atoms performs a ballistic motion away from the surface). Further elements of the model are surface mobility, attractive forces between adsorbed O-atoms (i.e. adsorbate-adsorbate interaction), and in-diffusion of O atoms into the 2nd and deeper layers to form 2D and 3D oxide. Input data are, when available, taken from experiments or first-principles calculations. The results of this computational work are compared to the experimental results by Brune et al. The calculated surface configurations of chemisorbed O-atoms at 300 K in the low coverage regime, based on the hot dimer dissociation model, are in good agreement with the observed experimental STM data. The simulations of thermal annealing of chemisorbed oxygen islands are in fair agreement with the observed island kinetics by Trost et al. (J. Chem. Phys. 108 (1998) 1740). In the latter case, the O-O interaction strength is a crucial parameter. The present simulation model provides a useful platform for further simulations of Al oxidation. @FootnoteText@ Keywords: Monte Carlo simulation, surface oxidation, oxide nucleation and growth, hot chemisorption, metal oxidation, kinetics, aluminium.