Kinetics of the reaction OH + SO₂ in He, N₂, and O₂ at low pressure

The rate constants of the gas-phase reaction of OH with SO₂ for M = He, N₂, and SO₂ have been determined by using the discharge flow/resonance fluorescence technique. The termolecular rate constants (all in units of cm⁶ molecule^-2 s^-1) and the corresponding experimental conditions are as follows: k(M=He) = (1.1 ± 0.3) × 10^-32 exp[(640 ± 200)/T] (280-413 K, 1-6 Torr); k(M=SO₂) = (3.3 ± 1.5) × 10^-31 exp[(1055 ± 500)/T] (280-363 K, P < 0.23 Torr); k(M=N₂) = (2.4 ± 0.7) × 10^-31 (298 K, 0.6-4.5 Torr); the uncertainties represent 95% confidence limits. The rate constants are in reasonable agreement with Leu's results. The rate constant for M = O₂ was also estimated to be (1.0-1.8) × 10^-31 cm⁶ molecule^-2 s^-1 at 298 K, smaller than previous measurements.