Quantum Mechanical Basis for the Cubes Models in Gas–Surface Scattering Theory, and an Experimental Test

It is suggested that there is a quantum mechanical basis for the classical flat surface (cubes) models of gas–surface scattering, the important characteristic of which is the assumption of conservation of tangential momentum of a scattering gas molecule. The theory is applied to the diffractive system He–LiF, and it is shown that existing experimental data confirm some predictions of the theory.