Rate constants for atomic hydrogen + oxygen + M at 298 K for M = helium, nitrogen, and water

The rate constants of the three-body recombination reaction H + O/sub 2/ + M (M = He, N/sub 2/, H/sub 2/O) were measured from 4.79 to 30.1 Torr at room temperature by the discharge-flow technique. The respective rate constants obtained are (2.6 +/- 0.2) x 10/sup -32/, (6.1 +/- 0.9) x 10/sup -32/, and (6.4 +/- 0.8) x 10/sup -31/ cm/sup 6/ s/sup -1/. Although the rates for he and N/sub 2/ can be rationalized in terms of existing theory, that for H/sub 2/O implies a collision efficiency greater than 1. This situation can be rectified by use of the total quantum mechanical scattering cross section instead of the Lennard-Jones cross section commonly used.