Gas-surface scattering distributions according to the hard-spheroid model

Gas-surface scattering distributions are calculated on the basis of the hard-spheroid model. This new model is related to the hard-cube model but incorporates surface structure by letting the surface atoms have hard spherical caps. Surface structure is found to reduce the maximum scattered intensity and to broaden the scattering distribution. The decrease in the maximum scattered intensity is most pronounced for a light gas. Broadening is asymmetric relative to the direction of maximum scattered intensity in that backscattering towards the surface is favored. Adding surface structure to the hard-cube model improves significantly the agreement between model predictions and experimental results.