Multiphonon inelastic scattering of helium atoms from crystal surfaces

Energy-resolved measurements of diffuse multiphonon inelastic He scattering from the NaCl(001) surface are presented for a range of energise and temperatures which span the region from quantum-mechanical to semiclassical behavior. A theoretical model developed for explaining the scattering process gives good quantitative agreement with the data and shows that the strong dependence of the scattering distribution on the nature of the atom-surface interaction can be used to obtain important information on the He-surface potential