Theoretical Study of Intermolecular Energy Transfer of an Electronically Excited Diatomic Molecule by Atom Impact: He( Exp 1 S) + H sub 2 (B Exp 1 sigma exp + /sub U/)

摘要

An ab initio potential energy surface (pes) for He + H sub 2 (B exp 1 sigma +/sub u/) has been determined using self-consistent field plus configuration interaction methods. The long-term interactions are described by a multipole expansion. The He-H sub 2 (B exp 1 sigma exp + /sub u/) interaction energy is much more anisotropic than those of ground state systems studied to date. As a first step in the dynamics studies, cross sections for rotational excitation at c.m. energies 0.015-0.105 eV have been computed in the rigid-rotator model using the space-fixed coupled-channel formalism and an analytical fit to the ab initio pes. Partial inelastic cross sections display a high degree of structure, which appears to be mainly due to the anisotropy of the interaction energy. The magnitudes of total cross sections for delta j = +-2 transitions are comparable to those for ion-molecule systems. 13 refs., 5 figs., 3 tabs. (ERA citation 11:001555)