Rate constant for the reaction of O with H2 at high temperature by resonance absorption measurements of O atoms

Resonance Absorption Spectroscopy (ARAS) has been used to measure O-atom concentration behind reflected shock waves in the temperature range 2690–3360 K at total pressures of about 250 kPa and using mixtures of N2O and H2 highly diluted in Ar. For the chosen experimental conditions, only a few elementary reactions exerted an appreciable influence on the O-atom profile so that the rate coefficient k2 for the reaction O + H2 → OH + H, directly responsible for the oxygen atom concentration decrease could be deduced by comparison between the experiment and computed simulation. In the actual temperature range we found: k2(cm3 mol−1 s−1) = 9.25 × 1014 exp(−9740/T(K)), with a percentage standard deviation of 8%. The influence of experimental uncertainties is discussed. This rate constant is compared with those reported previously in the literature.