The reactions of IO with HO2, NO and CH3SCH3:: Flow tube studies of kinetics and product formation

Rate coefficients for the reaction between IO and HO2 and between IO and NO were obtained using a low-pressure flow tube at total pressures of 1.0-2.0 Torr of He, and between 353 and 273 K. Reactants and products were detected using a quadrupole mass spectrometer. The temperature-dependent rate coefficient for the reaction between IO and HO2 is described by k(2) = (2.2 +/- 0.6) x 10(-11) exp{(400 +/- 80)/T} cm(3) s(-1). The temperature-dependent rate coefficient for the reaction between IO and NO is described by k(4) = (8.3 +/- 2.3) x 10(-12) exp{(269 +/- 85)/T} cm(3) s(-1). The rate coefficient at 298 K (and 2.5-2.7 Torr He) for the reaction of IO and CH3SCH3 was found to be k(5) = (1.6 +/- 0.3) x 10(-14) cm(3) s(-1). At all the temperatures used in this study the only products observed were HOI from reaction (2), NO2 from reaction (4), and CH3S(O)CH3 from reaction (5). [GRAPHICS] The new results for reactions (2) and (4) are compared to existing measurements, and combined with selected data sets to make recommendations for the temperature-dependent rate coefficients.