ANALYSES OF RECENT EXPERIMENTAL AND THEORETICAL DETERMINATIONS OF E-H-2 VIBRATIONAL-EXCITATION CROSS-SECTIONS - ASSESSING A LONG-STANDING CONTROVERSY

During the last four years, we have undertaken a major effort to resol ve a serious, long-standing discrepancy between various experimental a nd theoretical determinations of the cross section for the upsilon0 = 0 --> upsilon = 1 vibrational excitation of H-2. This effort has invol ved crossed electron-beam molecular-beam measurements of relative angu lar distributions, measurements of transport coefficients in mixtures of H-2 and various rare gases, and ab initio theoretical calculations using a vibrational close-coupling formalism with an exact treatment o f non-local exchange effects. The discrepancy remains unresolved-a fac t with potentially wide-ranging consequences for beam experiments, the ory, and the unfolding of inelastic electron-molecule cross sections f rom swarm data. New analyses of the transport data and the application of a new method of extrapolating angular distributions beyond the ran ge of measurement sheds light on this disagreement and its implication s.