Differential cross sections for the competing charge-transfer reactions Kr+(2P3/2) + Kr(1S0) → Kr(1S0) + Kr+(2P3/2) and Kr+(2P3/2) + Kr(1S0) → Kr(1S0) + Kr+(2P1/2)

Abstract

The crossed-beam method was used to investigate the charge-transfer reaction of Kr+(2P3/2) with Kr at collision energies of 9.2 and 19.9 eV. A weak plasma ion source was used to generate a nearly pure Kr+(2P3/2) beam. The purity of the beam was tested by using CH4 as a probe reaction; because Kr+(2P3/2) generates [Formula: see text] and Kr+(2P1/2) generates [Formula: see text], the ratio, [Formula: see text], could be used to evaluate the spin-state composition of the reactant ion beam.The resonant reaction occurs via a process well described by a rectilinear-trajectory impact-parameter model proceeding via a [Formula: see text], intermediate in which the electron "hole" is shared equally by both partners. Also evident is the endoergic fine-structure reaction with ΔJ = −1. At 9.2 eV, the endothermic-channel product is scattered at a definite angle, suggesting a short-range interaction that selects a particular impact parameter. At the higher energy investigated, the fine-structure splitting is also evident once the data are deconvoluted. However, the scattering angle is reduced to near zero, corresponding to nearly rectilinear tragectories for both channels at this energy. The population of both channels is in general accord with accepted theories for ion–atom charge exchange, but the energy range at which it is observed is far removed from that predicted (we observe nearly equal cross sections for both channels at energies three orders of magnitude lower than those predicted by theory).