The role of long-range interactions on the selectivity of gaseous molecule-surface scattering

A state-to-state semiclassical collisional method is adopted to emphasize the basic role of long-range interactions on the scattering of gaseous molecules from surfaces. Such role emerges at collision energies sufficiently low to promote efficient trapping in the potential well controlling the physical adsorption. The scattering of hydrogen and oxygen molecules impinging on a graphite surface with a well-defined roto-vibrational state is analysed adopting for each system two potential energy surfaces that differ for some important features. Collision mechanism and final rotational distributions highlight the relation between selectivity of inelastic scattering and peculiarities of the long-range interactions.