Determination of the Rate Constant of the O + H 2 →OH + H Reaction using Atomic Oxygen Resonance Fluorescence and the Air Afterglow Techniques

Abstract

Measurements of the rate of the reaction[Formula: see text]were made over the temperature range of 347 to 832 K and a pressure range of 140 to 739 N m −2 . Experiments were carried out using a discharge fast-flow system with a fixed observation port. O atoms, generated by the N + NO→N 2 + O reaction, were reacted with H 2 added downstream under pseudo first-order conditions [Formula: see text] Relative O atom concentrations were determined using two independent methods: atomic resonance fluorescence at 130.6 nm and the air afterglow technique., The rate coefficients derived from our data can be expressed as k 1 = (8.3 ± 3.8) × 10 −12 exp {−36.0 ± 2.0 kJ mol −1 RT} cm 3 molecule −1 s −1 (by resonance fluorescence), and k 1 = (8.8 ± 5.0) × 10 −12 exp {−34.9 ± 2.0 kJ mol −1 /RT} cm 3 molecule −1 s −1 (by air afterglow method). Comparisons are made with selected published results.The Arrhenius plot of our data shows no evidence of curvature at low temperature.