Coupled states approximation study of inelastic H+–H2 collisions at 3.7 eV

Abstract

Using the diabatic ground state H⁺₃ surface given in analytic form by Giese and Gentry, a coupled‐states study of the rotational excitation of H₂ (taken as a rigid rotor) by proton impact is made at 3.7 eV. Transitions 0→j′, with j′=0,2,4,...,26, are considered, and one finds a broade distribution in final rotor state j′ which is consistent with recent beam experiments. Despite long‐range rotational coupling produced by the charge‐quadrupole interaction, the coupled‐states method gives a good description of the rotational excitation process as is demonstrated by comparison to standard close‐coupling cross sections. Intermultiplet transitions (neglected in the coupled‐states approximations) are shown to be less important in the high energy limit.