Semiclassical theory of atom-solid-surface collisions: Application to He–LiF diffraction

The semiclassical theory of gas-solid-surface collisions is applied to the diffractive He–LiF system. It is shown that uniform semiclassical results are in good agreement with high quality quantum-mechanical results. The present study suggests that classically forbidden contributions should not always be ignored when both classically allowed and forbidden contributions are present. The experimental results of O'Keefe et al. are examined.