Calculated rotational and vibrational excitation rates for electron—HeH+ collisions

Molecular R-matrix calculations are performed at a range of energies to give rotational and vibrational excitation and de-excitation cross-sections and, hence, rates for electron collisions with HeH+ up to electron temperatures of 20 000 K. Critical electron densities are also given. The rotational calculations include the Coulomb-Born completion of the cross-sections for high l values. Rates for the transition j = 0 → 2, which have previously been assumed to be negligible, are found to be up to half those for j = 0 → 1, raising the prospect of observing the HeH+j = 2 → 1 emission line at 74.8 μm.