NEAR-THRESHOLD VIBRATIONAL-EXCITATION OF H-2 BY ELECTRON-IMPACT - RESOLUTION OF DISCREPANCIES BETWEEN EXPERIMENT AND THEORY

New measurements and calculations of near-threshold (0.5-5.0 eV) e-H-2 vibrational-excitation cross sections challenge previous determinations based on transport analysis. Elastic and v(o) = 0 --> v = 1 cross sections measured in a crossed electron-molecular-beam apparatus agree well with values calculated using a vibrational close-coupling theory with a separable representation of exchange, particularly at energies below 2.0 eV, but are incompatible with cross sections derived via analysis of electron-swarm transport data.