Rate Coefficients for the OH + CF3I Reaction between 271 and 370 K

The rate coefficient, k 1, for the reaction OH + CF 3 I → products was measured under pseudo-first-order conditions in hydroxyl radical, OH. OH temporal profiles were monitored by laser-induced fluorescence (LIF), and CF 3 I concentrations were determined by UV/Visible absorption. We determined k 1 (T) to be (2.10 ± 0.80) × 10 -11 exp[−(2000 ± 140)/T] cm 3 molecule -1 s -1, over the temperature range 271 to 370 K. The quoted uncertainties are 2σ (95% confidence limits, σ A = Aσ lnA ). Previous measurements of k 1 (T) are compared with our values, and possible reasons for the discrepancies are discussed. The heat of formation of HOI is deduced to be less than −16 kcal mole -1, if the products of reaction 1 are mostly HOI and CF 3 . These measurements support the earlier conclusion that the reaction of OH with CF 3 I plays a negligibly small role in the atmospheric removal of CF 3 I.