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 re lative 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 desc ribe the molecular anion in its unstable region. The charge transfer c ross section for Na- + H is compared to the results of a perturbed sta tionary state calculation which uses the average width inferred from t he detachment results and a term of the form H12 = beta exp -gammaR to describe the long-range coupling between the A 2SIGMA and X 2SIGMA st ates of NaH-. This latter calculation underestimates the observed low energy cross section for charge transfer.