Three body electron–ion recombination in molecular gases

The rate constant for the recombination of electrons with positive ions, α (cm3 s−1), has been measured at 292 K as a function of pressure in gaseous H2O, NH3, (CH3)2CO, CH3C1, CO2, and neo-C5H12. In all cases α is found to increase with increasing gas density, N (molecules cm−3), and over the density ranges studied can be described by a combination of a two and three body process, i.e., α=α2+α3N. In the same order of the gases as given above, the values found for 106 α2 are 4.1, 5.6, 6.4, 7.1, 3.9, and 7.0 cm3 s−1 and for 1025 α3 are 270, 69, 55, 26, 5.8, and 2.5 cm6 s−1. The values of α3 are discussed in the light of existing theory together with the known characteristics of electron neutral collisions in the gases studied.