Kinetic study of the reaction of OH with CH3I revisited
Résumé
A flash photolysis resonance fluorescence technique has been employed to investigate the kinetics and mechanism of the reaction of OH(X2\textgreekP) radicals with CH3I 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 (A2\textgreekS+ → X2\textgreekP transition at \textgreekl = 308 nm) following FP of H2O/CH 3I/He mixtures. The OH(X2\textgreekP) radicals were produced by FP of H2O in the vacuum-UV at wavelengths \textgreekl \textgreater 115 nm using a commercial Perkin-Elmer Xe flash lamp. Decays of OH in the presence of CH 3I are observed to be exponential, and the decay rates are found to be linearly dependent on the CH3I concentration. The measured rate coefficients for the reaction of OH with CH3I are described by the Arrhenius expression kOH+CH3I = (4.1 ± 2.2) × 10 -12 exp [(-1240 ± 200)K/T] cm3 molecule -1s-1. The implications of the reported kinetic results for understanding the CH3I chemistry of both atmospheric and nuclear industry interests are discussed. © 2011 Wiley Periodicals, Inc.