Molecular beam studies on inelastic collision processes of methane molecules at a Pt(111) surface

Inelastic collision processes of CH4 at a Pt(1 1 1) surface have been analy zed by means of super-sonic molecular beam technique. Obtained results of t he angular intensity distribution of the reflected CH4 with the incident ki netic energy ranging from 190 to 350 meV are found to qualitatively agree w ith the prediction from the classical collision model. Surface temperature dependence of the speed distributions of the reflected CH4 qualitatively fo llows the prediction at the surface temperature below 500 K, but deviates f rom the prediction as the surface temperature increases under the irradiati on of CH4 with higher kinetic energies, where decomposition of CH4 takes pl ace. The discrepancy of data from the model can be understood by introducin g into the model decreased effective surface mass and increased surface " r oughness". (C) 2001 Elsevier Science B.V. All rights reserved.