Rotational Energy Transfer in Molecular Collisions and Parameters of Power-Gap "Law"

Abstract

The quantum mechanical integral inelastic cross-sections for the rotation transitions in a diatomic molecule with an atom were computed and analysed by using the empirical power-gap law over a wide range of coliisioii energy. A well-known parameter, ΙΔEΙ*, of the power-gap law was estimated by observing a rapid fall of cross-sections for the rotational energy transfer, ΙΔE Ι > ΙΔEΙ*. It was found that ΙΔEΙ* corresponds to classical limit of maximum amount of rotational energy transfer permissible by the angular momentum conservation constraints and the hard ellipsoid potential model provided the hard ellipsoid potential surface is represented by the classical turning point surface of the real potential employed in the computation of cross-sections. Such an agreement is shown to be useful in the determination of the difference of major and minor axes of the intermolecular-potential ellipsoid from the knowledge of the cross-sections and the power-gap law. PACS numbers: 34.50.Ez, 34.50.—s