Inelastic collisions between C+(2P) and H2

The author assesses the effect on the C + ( 2 P o 1 2/- 2 P o 3 / 2 ) excitation cross section of introducing a coefficient into the harmonic expansion of the interaction potential which was omitted in earlier work. This effect is found to be much smaller than those associated with other uncertainties in the potential at short and intermediate range. The contribution of simultaneous fine-structure excitation of the ion and rotational excitation of the molecule to the total rate coefficient for fine-structure excitation is found to be important at high energies.