Pulse radiolysis studies of ion-electron recombination in gaseous argon

Abstract

Using pulse radiolysis techniques, rates of recombination of Ar2+ ions with electrons in bulk argon were measured over a wide pressure range (150 to 1065 torr) at bulk gas temperatures of 295, 335, and 375 K. No pressure dependence for the total recombination rate constant was observed at any temperature studied. This observation is consistent with the model, whereby the encounter pair is stabilized by electron energy loss while in the Coulomb field of the cation. The presence of a Ramsauer minimum in the electron/argon atom momentum-transfer cross section versus energy profile means that, at low energies, energy loss is very slow. The neutral-assisted three-body recombination mechanism in argon does not significantly enhance the total rate of recombination above the two-body rate.