Mixtures of hydrogen and oxygen dilute in argon were heated by both incident and reflected shock waves to measure the rate coefficient of the H2/O2 mechanism branching reaction H + O2 → OH + O (2) in the temperature range 1450-3370 K. Time histories of OH(X2Π) were monitored by using narrow-line-width laser absorption at 306.7 nm. A detailed kinetic analysis of the data in rich mixtures yielded the following rate coefficient expression: k2 = (9.33 ± 0.40) × 1013 exp[-(14800 ± 170) cal mol-1/RT, K] cm3 mol-1 s-1. In addition, H atom production was measured with atomic resonance absorption spectroscopy (ARAS) in incident shock experiments over the temperature range 1450-2152 K both simultaneously with OH detection and in separate experiments. The rate coefficient data obtained by ARAS are in excellent agreement with those based on the OH absorption but exhibit larger scatter. The rate coefficient derived from OH measurements lies 27-38% below the determination of Frank and Just (1985) at 1700-2500 K and agrees with that of Pirraglia et al. (1989), within their stated uncertainty, at overlapping temperatures of 1450-1705 K. © 1990 American Chemical Society.
