Kinetics of the reaction OH+H2O2→HO2+H2O

An experimental study of the title reaction over the temperature range 250 to 459 K is described that uses the discharge-flow technique, laser-induced–fluorescence detection of OH and simultaneous monitoring of O and H atoms. In a teflon or halocarbon wax-coated flow tube, the reaction is well behaved and free from surface effect interference, but this is not true on clean Pyrex. OH radicals are generated in three different ways and at low initial concentrations (4 to 8×1010 cm−3) in order to eliminate side reactions. The rate constant is found to be (1.69±0.26)×10−12 at 298 K and (2.96±0.50)×10−12 exp[−(164±52)/T] cm3 s−1 over the above temperature range, a factor of two higher at 298 K and factors of 3 to 5 higher at 10 to 30 km altitude in the terrestrial atmosphere than earlier studies have indicated. These studies are re-examined, and for several of them, arguments are presented that reduce the discrepancy. The effects of the higher rate constant on atmospheric processes and on some recent laboratory measurements of other reactions are discussed briefly.