Recent experiments have reported measurements of rainbow scattering features in the angular distributions of hyperthermal Ar colliding with LiF(001) [Kondo et al., J. Chem. Phys. 122, 244713 (2005)]. A semiclassical theory of atom-surface collisions
recently developed by the authors that includes multiphonon energy transfers is used to explain the temperature dependence of the measured scattered angular distribution spectra.
Prompted by recent experimental developments, a theory of surface scattering of fast atoms at grazing incidence is developed. The theory gives rise to a quantum mechanical limit for ordered surfaces that describes coherent diffraction peaks whose the
rmal attenuation is governed by a Debye-Waller factor, however, this Debye-Waller factor has values much larger than would be calculated using simple models. A classical limit for incoherent scattering is obtained for high energies and temperatures. Between these limiting classical and quantum cases is another regime in which diffraction features appear that are broadened by the motion in the fast direction of the scattered beam but whose intensity is not governed by a Debye-Waller factor. All of these limits appear to be accessible within the range of currently available experimental conditions.
Calculations are carried out for the scattering of heavy rare gas atoms with surfaces using a recently developed classical theory that can track particles trapped in the physisorption potential well and follow them until ultimate desorption. Comparis
ons are made with recent experimental data for xenon scattering from molten gallium and indium, systems for which the rare gas is heavier than the surface atoms. The good agreement with the data obtained for both time-of-flight energy-resolved spectra and for total scattered angular distributions yields an estimate of the physisorption well depths for the two systems.
