MULTIPHONON BACKGROUND IN ATOM SURFACE SCATTERING

A quantum mechanical theory for the multiphonon inelastic background appearing in the energy resolved measurements of low energy atom-surface scattering is presented. Simple expressions for the differential reflection coefficient are given for the semiclassical and extreme semiclassical limits of high surface temperatures and large atomic translational energies. Measurements of the inelastic background give directly the form factor of the interaction potential for inelastic scattering. It is shown that there can be either net gain or loss of energy by the scattered particles, depending on the relative incident particle energy to the surface temperature. The relation to previous semiclassical theories is discussed.