Collisions of polyatomic molecules with solid surfaces: A semiclassical stochastic trajectory approach

Abstract

The semiclassical stochastic trajectory method is extended to the study of vibrational excitation and relaxation of polyatomic molecules in collisions with nonrigid solid surfaces. The technique involves a quantum-mechanical treatment of the molecular vibrational modes and a classical treatment of the translational and surface motion. Surface temperature effects are incorporated in the method through use of the generalized Langevin equation. The sudden approximation is used to treat the molecular rotational motion. Calculations of vibrational transition probabilities are reported for the collisions of CO2 with a Pt(111) surface, and these probabilities, when relatively small, are found to be quite sensitive to surface temperature. The results are relevant to recent experiments on the excitation and relaxation of the vibrational modes of CO2 in collisions with surfaces.