Quantum‐Mechanical Treatments of Rotationally Inelastic Molecule‐Surface Scattering

Quantum‐mechanical approximation methods and calculations for rotational transitions in molecule‐surface collisions are reviewed. The methods are analyzed with regard to predictions of several observable effects: (1) Large ΔJ (rotational quantum number) transitions, and rotational rainbow scattering. (2) The relation between rotational and diffractive transitions. (3) Scaling properties of the rotationally‐inelastic scattering amplitudes. (4) Trapping and resonances induced by rotational‐translational energy transfer. The methods examined with regard to some of these effects include: coupled‐channel calculations; the Sudden approximation with regard to both the rotational and the diffractive transitions, and the hard corrugated wall model. It is concluded that whilst available methods provide a qualitative description of the effects mentioned, quantitative treatment of real systems remains an open problem. The main difficulties in formulating a satisfactory quantitative model are examined. Finally, the article presents new results on molecular reorientation processes (ΔM_J transitions) in molecule‐surface collisions. It is shown, using the Sudden approximation, that molecular reorientation probabilities should reflect sensitively on surface structural corrugation.