Two-Body Positive Ion-Negative Ion Neutralization.
Final rept. 19 Oct 74-31 Dec 78,
SRI INTERNATIONAL MENLO PARK CA MOLECULAR PHYSICS LAB
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The results are presented of a combined experimental and theoretical investigation of ion-ion mutual neutralization processes relevant to the earths ionosphere. Experimetal results from our merged beams apparatus thermal rate coefficients reduced from cross sections for nineteen sets of reactants and also those from the more recent Birmingham experiments using a flowing afterglow are reviewed. The advantages and disadvantages of both techniques are discussed. A discrepancy in the NO NO-3 results is attributed to an effect of excitation in the NO-3 beams of the merged beams, and it is concluded that because of these effects the flowing afterglow is presently better for obtaining rate coefficients for complex molecular ions. Our theoretical work has focused on two neutralization mechanisms electron transfer and tidal distortion. A new formulation of the collision dynamics, Semiclassical Perturbation Scattering Theory, was developed and used to estimate the importance of the tidal distortion mechanism. It is concluded that the electron transfer mechanism dominates in reactions of simple ions and small clusters, but that the tidal distortion becomes more important for multiply hydrated reactants. An approximate scaling formula for the rate constants is obtained that fits a wide range of experimental data involving simple ions and small clusters with an accuracy of about or - 30. Author
- Atmospheric Physics
- Physical Chemistry