Angular and velocity distributions characteristic of the transition between the thermal and structure regimes of gas-surface scattering

Angular variations in the kinetic energy of scattered species are found to provide a useful probe of the transition between gas-surface scattering regimes, complementing angular flux distributions. As incidence energies exceed a few eV, these change from being consistent with scattering from an extended target to being more typical of scattering from individual atoms. Results are presented for the Xe/Pt(111) system and are supported by detailed trajectory calculations.