H+O2+M(=N2,H2O,AR) 3-BODY RATE COEFFICIENTS AT 298-750-K

Three-body rate coefficients for reactions of H + O2 + M where M = N2 and H2O have been measured in a high-temperature flow reactor as a function of temperature up to 750 K. Room-temperature rate coefficients for M = Ar have also been quantified. The rate coefficients are measured by the flash photolysis method where atomic hydrogen is produced by excimer laser photolysis of precursor molecules (H2S or H2O) and then probed by either laser-induced fluorescence or resonance absorption. The rate coefficient measurements for nitrogen (298-580 K) can be described by the Arrhenius expression k(N2) = (2.9 +/-0.8) x 10(-33) exp[(825 +/- 130)/ 71 cm6 molecule-2 s-1. Rate coefficients measured for water are k(H2O)(575) = (1.2 +/- 0.3) X 10(-31), k(H2O)(650) = (1.0 +/- 0.3) X 10(-31), and k(H2O)(750) = (1.2(-0.6)+0.9) X 10(-31) CM6 MoleCUle-2 s-1. Room-temperature measurements for Ar gave a rate coefficient of k(Ar)(298) = (2.1 +/- 0.2) X 10(-32).