Kinetic study of the reaction of OH with CH 3 I revisited

A flash photolysis resonance fluorescence technique has been employed to investigate the kinetics and mechanism of the reaction of OH(X 2 Π) radicals with CH 3 I over the temperature and pressure ranges 295–390 K and 82–303 Torr of He, respectively. The experiments involved time‐resolved RF detection of the OH (A 2 Σ + → X 2 Π transition at λ = 308 nm) following FP of H 2 O/CH 3 I/He mixtures. The OH(X 2 Π) radicals were produced by FP of H 2 O in the vacuum‐UV at wavelengths λ > 115 nm using a commercial Perkin‐Elmer Xe flash lamp. Decays of OH in the presence of CH 3 I are observed to be exponential, and the decay rates are found to be linearly dependent on the CH 3 I concentration. The measured rate coefficients for the reaction of OH with CH 3 I are described by the Arrhenius expression k OH+CH3I = (4.1 ± 2.2) × 10 −12 exp [(−1240 ± 200)K/T] cm 3 molecule −1 s −1 . The implications of the reported kinetic results for understanding the CH 3 I chemistry of both atmospheric and nuclear industry interests are discussed. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 547–556, 2011