The recombination of H3+ ions with electrons: dependence on partial pressure of H2

We observed an increase in the effective recombination coefficient (αeff) of the recombination of H3+ ions with electrons with a number density of H2, n(H2). With increasing n(H2) from 1×1011 to 2×1012 cm−3 the αeff increased from 1.3×10−8 to 1.5×10−7 cm3 s−1. The dependence of αeff on n(H2) indicates that the recombination of H3+ ions in an afterglow plasma is a complex process in which collisions with H2 take place. It is stressed that at conditions corresponding to plasma in interstellar space the dissociative recombination of H3+ ions is very slow with a rate coefficient α⩽1.3×10−8 cm3 s−1.