ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Angular distributions of He*(2 1S, 2 3S) scattered by D2 and H2 measured in crossed supersonic molecular beams at collision energies in the range 1.0–2.4 kcal/mol are analyzed to yield anisotropic optical potentials that simultaneously reproduce these data along with quenching rates and ionization cross sections. Comparison with ab initio calculations of the potentials by Cohen and Lane and Hickman, Isaacson, and Miller shows very good agreement. The results are combined with one-electron model potential calculations to probe the nuclear and electronic dynamics involved in these collisions. Quenching or Penning ionization is found to occur mainly through broadside attack of He* on H2, despite the fact that the occupied σg orbital on H2 has greater spatial extent along the bond axis than perpendicular to it. An implication is that Penning ionization electron spectroscopy (PIES) experiments on larger molecules cannot be interpreted simply on the basis of van der Waals radii and spatial extent of various molecular orbitals; the nature of the excited-state potential surface may play a dominant role in determining these spectra.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.448313
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