Rate coefficients for the reaction of OH with Cl2, Br2, and I2 from 235 to 354 K

Rate coefficients for the reaction of OH with Cl2, (k1), Br2, (k2) and I2, (k3), were measured under pseudo-first-order conditions in OH. OH was produced by pulsed laser photolysis of H2O2 (or HNO3) and its temporal profile was monitored by laser-induced fluorescence. The measured rate coefficients for k1 (231–354 K) and k2 (235–357 K) are: k1 (T) = (3.77 ± 1.02) × 10−12 exp[−(1228 ± 140)/T] cm3 molecule−1 s−1 k2 (T) = (1.98 ± 0.51) × 10−11 exp[(238 ± 70)/T] cm3 molecule−1 s−1 k3 was independent of temperature between 240 and 348 K with an average value of (2.10 ± 0.60) × 10−10 cm3 molecule−1 s−1. The quoted uncertainties are 2σ (95% confidence limits, 1σA = AσlnA) and include estimated systematic errors. Our measurements significantly im-prove the accuracy of k1. This is the first report of a slight negative temperature dependence for k2 and of the temperature independence of k3.