We report the evaluation of ab initio molecular data that are relevant to t
reat the charge exchange processes C2+ (S-1, P-3) + H-2 at low energies. Fo
r the impact energy range 600-10 000 eV, we calculate the cross sections fo
r these processes. Comparison with the measured data of Unterreiter et al (
1991 J. Phys. B: At. Mel. Opt. Phys. 24 1003) yields a new, more accurate e
valuation of the content of metastable ions in their primary beams.