Electron–ion recombination rate constants for some compounds of moderate complexity

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Abstract
Electron–ion recombination has been studied for the systems N2, CH4, C3H8, neopentane, NH3, and CO2 by use of a microwave conductivity method coupled with pulse radiolysis. Rate constants were determined by analysis of the directly observed electron disappearance. All data pertain to 297 °K. Corrections were made for competing electron losses by extrapolation to zero of a plot of apparent second‐order rate constant versus reciprocal of initial electron concentration. No attempt was made to try to identify the positive ions present. The rate constants for the first four compounds showed little change with pressure over the range 1–100 torr with the value found at 100 torr about 20%–50% higher than that at 1 torr. Values for pressures of 10–50 torr are 2.5×10−6 for N2, 3.9×10−6 for CH4, 5.8×10−6 for C3H8, and 4.2×10−6 for neopentane (all cm3 molecule−1 ⋅sec−1). The values found for NH3 varied from 4.6×10−6 at 1 torr to 11.2×10−6 at 10 torr. Data for CO2 were less reliable but showed a change of from 4×10−6 at 1.5 torr to 11×10−6 at 100 torr.