The reactions of IO with HO2, NO and CH3SCH3: Flow tube studies of kinetics and product formation
Abstract
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 k2 = (2.2 ± 0.6) × 10−11 exp{(400 ± 80)/T} cm3 s−1. The temperature-dependent rate coefficient for the reaction between IO and NO is described by k4 = (8.3 ± 2.3) × 10−12 exp{(269 ± 85)/T} cm3 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 k5 = (1.6 ± 0.3) × 10−14 cm3 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).
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.