Slow collisions of Na-and K-with atomic hydrogen

Total cross sections for electron detachment and charge transfer have been measured for collisions of Na - and K - with atomic hydrogen for relative collision energies ranging from 2-20 eV. The cross sections for detachment are considerably larger than those for charge transfer and the experimental results for Na - +H are analysed with a model which employs available potential energy curves and an average width to describe the molecular anion in its unstable region. The charge transfer cross section for Na - +H is compared to the results of a perturbed stationary state calculation which uses the average width inferred from the detachment results and a term of the form H 12 = beta exp - gamma R to describe the long-range coupling between the A 2 Sigma and X 2 Sigma states of NaH - . This latter calculation underestimates the observed low energy cross section for charge transfer.