Rate coefficients for the gas-phase reaction of OH radicals with dimethyl sulfide: temperature and O2 partial pressure dependence
Abstract
Rate coefficients for the gas-phase reaction of hydroxyl (OH) radicals with dimethyl sulfide (CH3SCH3, DMS) have been determined using a relative rate technique. The experiments were performed under different conditions of temperature (250–299 K) and O2 partial pressure (∼0 Torr O2−380 Torr O2), at a total pressure of 760 Torr bath gas (N2 + O2), in a 336 l reaction chamber, using long path in situ Fourier transform (FTIR) absorption spectroscopy to monitor the disappearance rates of DMS and the reference compounds (ethene, propene and 2-methylpropene). OH was produced by the photolysis of H2O2. The following Arrhenius expressions adequately describe the rate coefficients as a function of temperature (units are cm3 molecule−1 s−1): k = (1.56 ± 0.20) × 10−12 exp[(369 ± 27)/T], for ∼0 Torr O2; (1.31 ± 0.08) × 10−14 exp[(1910 ± 69)/T], for 155 Torr O2; (5.18 ± 0.71) × 10−14 exp[(1587 ± 24)/T], for 380 Torr O2. The results are compared with previous investigations.