Rotationally inelastic scattering of hydrogen molecules and the non-spherical interaction

Abstract

Molecular-beam scattering experiments on state-to-state differential cross-sections for rotational transitions of hydrogen molecules are a sensitive probe for both the isotropic and the anisotropic interaction potential with other atoms and molecules. New experimental results on the weakly coupled system D₂+ Ar allow reliable determination of the repulsive part of the complete potential. It is compared with the well known D₂–Ne ₂ potential and recently proposed model potentials which predict the general behaviour but not the details. For the important H₂–H₂ interaction differential cross-sections for 0→2 transitions in HD + D₂ and D₂+ H₂ collisions are presented. The evaluation of these data leads to repulsive anisotropic potential terms which show the same shift of 0.1 Å to smaller R-values with respect to the best ab initio calculation found previously for the isotropic interaction.