Theoretical study of energy transfer in molecule--solid collisions: H2, D2+Ag(111)

A quantum mechanical calculation of the angular distribution of H2 and D2 scattered from a Ag(111) surface is presented. Energy transfer between the gas and the solid is included using an isotropic Debye model of the solid. The coupling of the rotational levels of H2, D2 with the phonon modes of the solid is investigated treating the molecules as rigid rotors. The results indicate that the mass difference between H2 and D2 is more important than the different rotational energy spacing in determining the angular scattering pattern. Differences between the present results and classical ''cubes'' models are observed and compared with experimental results