Coupledâ€�channel study of rotational excitation of an electronically excited diatomic molecule by atom impact: He(¹S)+H₂ (B ¹Î£⁺ _u)

Rotational energy transfer cross sections have been computed in the rigid rotor model, for the energy range 0.015–0.150 eV, using an analytic fit to ab initio interaction energies determined by others and the authors with large basis set CI approaches. Long�range interactions are described by a multipole expansion. The potential energy surface is highly anisotropic and leads to integral inelastic cross sections, typically larger than those involving ground state systems, in fair agreement with results obtained using a previously determined fit.