The effect of impact angle and corrugation on gas–surface energy transfer and sticking: A semiclassical study

A semiclassical model is derived for the scattering of an atom from a metal surface. The surface and bulk vibrations are treated quantum mechanically, and the translational motion of the gas particle is represented by a Gaussian wave packet. Equations of motion are derived for the average position and momentum of this wave packet in terms of the parameters which describe the gas–surface and gas–phonon interaction potentials. Multiphonon interactions are included to all orders, and the motion of the gas particle parallel to the surface is coupled to the lattice vibrations. Probabilities for energy transfer and trapping are computed. The way in which the normal and parallel (to the surface) components of the beam energy are mixed by the corrugation and the thermal fluctuations is examined. The effect this has on the variation of the trapping probability with beam energy and angle of incidence is discussed.