2001MNRAS.325..443F

Molecular R-matrix calculations are performed to give rotational excitation rates for electron collisions with linear molecular ions.
Result. are presented for CO⁺, HCO⁺, NO⁺ and H2⁺ up to electron temperatures of 10000K. De-excitation rates and critical electron densities are also given. It is shown that the widely used Coulomb-Born approximation is valid for Δj=1 transitions when the molecular ion has a dipole greater than about 2D, but otherwise is not reliable for studying electron-impact rotational excitation. In particular, transitions with Δj>1 are found to have appreciable rates and are found to be entirely dominated by short-range effects.