A HIGH-TEMPERATURE GUIDED-ION BEAM STUDY OF NA-2, NO, N-2) CHARGE-TRANSFER REACTIONS(X+ (X=O)

The high-temperature guided-ion beam method is used to measure absolut e, integral cross-sections for charge transfer reactions of sodium wit h O-2(+), NO+ and N-2(+) in the collision energy range between ca. 0.2 and 10 eV (CRI). At 1 eV the cross-sections are, respectively, 168, 2 9 and 57 Angstrom(2), with errors estimated at +/-40%. These experimen ts, involving molecular ions present in the ionosphere at altitudes of 80-110 km, were undertaken to improve the kinetic data available to t he community involved in modelling mesospheric meteoric metal layers. The cross-sections are extrapolated to thermal energy, and thermally a veraged rate constants are derived. The cross-sections are discussed w ith respect to the effects of vibrational excitation of the reactant i ons, which are produced by electron impact ionization. These results p ermit an improved inclusion of metal-atom reactions in the models, whi ch are now able to account for the kinetic energy range commensurate w ith the meteor ablation process.