Thermal Energy Charge-Transfer Reactions of Ar+ and Ar2+

Abstract

The rate coefficients for a number of thermal energy charge-transfer reactions are obtained with a recently completed selected ion flow tube (SIFT). The ion-molecule reactions studied involve Ar/sup +/ and Ar/sub 2//sup +/ with a variety of neutral molecules including O/sub 2/, CS/sub 2/, CO/sub 2/, SO/sub 2/, H/sub 2/O, H/sub 2/S, NH/sub 3/, NO SF/sub 6/, CH/sub 4/, N/sub 2/O, NO/sub 2/, and CO. The relative magnitudes of the observed rate coefficients are not in accord with an energy resonance model which requires favorable Franck-Condon factors. Furthermore the authors find that the dimer ion reaction rate constant is not always greater than that of the monomer with a specific neutral although there is greater phase space in the case of the dimer where the dissociative channel leads to a three-body final state. However, the proximity of the recombination energy of Ar/sup +/ and Ar/sub 2//sup +/ to a band in the photoelectron spectra of the neutral appear to explain the relative rates of the monomer and the dimer reactions with a specific neutral.