Inelastic gas-surface scattering. I. Formalism

Abstract
We present a method for calculating elastic and inelastic scattering probabilities for light particles, such as helium and molecular hydrogen, scattering from surfaces with which they weakly interact. The method is a unitary one-phonon approximation in which the scattering probabilities are calculated from thermally averaged amplitudes which are generated numerically. The thermal averaging procedure is more general than this application and could be applied to other systems with weak inelastic scattering. We also discuss an approximation for the gas-surface interaction potential that can greatly simplify calculations where it is applicable. Finally we present some preliminary results using this method to study rotationally mediated selective adsorption resonances in HD scattering from copper.