Adsorption dynamics of CO on Cu(1 1 0): a molecular beam study

Abstract

Molecular beam measurements of initial adsorption probabilities, S 0, as well as the coverage dependence of the adsorption probability, S( Θ), of CO on Cu(1 1 0) are presented. The influence of kinetic energy, polar impact angle, α i, azimuthal orientation ([1 0 0] and [ 1 1 ̄ 0 ]), and adsorption temperature, T s, on the adsorption dynamics have been studied. With regard to microkinetical models used to describe processes in heterogeneous catalysis, the dependence of the adsorption probability on the density of defects has been investigated. The surface has been characterized by measuring He atom angular distributions, He atom reflectivity curves, and LEED. The shape of the S( Θ) curves are consistent with a precursor mediated adsorption mechanism. For low temperatures T s⩽90 K, the adsorption dynamics are dominated by adsorbate assisted adsorption. Despite the pronounced difference in the surface corrugation along the different high-symmetry directions no significant differences in S 0 and S( Θ) were observed for the different azimuths studied.