Ion lifetimes in irradiated gaseous HCl

Abstract

An intermittent-field method has been used to measure ion lifetimes in gaseous HCl during irradiation by gamma rays under conditions of pressure, dose rate, and vessel geometry similar to those employed in radiolysis studies. At 23 °C, with HCl pressures from 119 to 660 Torr and dose rates from 5.5 to 86 × 1010 eV cc−1 s−1, the ion half-life ranged from 6 to 30 ms. The dependence on dose rate and pressure strongly indicated that ion neutralization occurred almost entirely in the gas phase. Values of α, the gas-phase combination coefficient, were calculated; at pressures above 246 Torr the value was constant and equal to 3.1 ± 0.3 × 10−6 cc ions−1 s−1. The addition of SF6 had little effect on α, while reducing the temperature to −79 °C increased α to 5.1 × 10−6.