Pulse radiolysis studies of ion–electron recombination in helium. Pressure and temperature effects

Abstract

Using pulse radiolysis techniques, rates of recombination of electrons with He+2 ions in the presence of helium over a wide pressure range (40–900 Torr) and at temperatures of 200, 235, 275, and 295 K were measured. Two- and three-body recombination processes were resolved, and a temperature dependence for the three-body recombination rate constant of T(−2.9±1.2)gas observed. This result agrees well with theoretical predictions of a temperature exponent of −2.5 by Bates and Khare and Pitaevskii, and remarkably well with recent work by Cao and Johnsen which gave a temperature exponent of −2.9 for the rate constant for three-body recombination of electrons with simple molecular ions in the presence of helium.