Electron-ion recombination rate constants in liquid and dense gaseous methane

Abstract

Electron drift mobilities, μ e, and electron-ion recombination rate constants, k r, in liquid and dense gaseous methane have been determined from the measurements of transient conductivities induced by X-ray pulse irradiation. The effect of external DC electric field on μ e and k r up to ca 0.4 Td (1 Td = 10 -17 V cm 2 molecule -1) in gas phase and ca 0.01 Td in liquid phase was examined, respectively. The observed k r values which were much smaller than those calculated by the reduced Debye equation in the lower electric field region, increase with increasing external electric field in both phases even in the region where μ e values are constant. In liquid phase the k r values seem to decrease in the region where μ e values begin to decrease with increasing electric field. The increase in k r values induced by the external electric field is tentatively attributed mainly to the increase in the drift velocity of excess electrons caused by the electric field.