Kinetic and mechanistic studies of the OH-initiated oxidation of dimethylsulfide at low temperature – A reevaluation of the rate coefficient and branching ratio

The pulsed laser photolysis–pulsed laser induced fluorescence (PLP–PLIF) technique has been used to study the reactions of OH with DMS and DMS-d6. The effective rate coefficient for the reaction of OH with DMS-d6 has been determined as a function of O2 partial pressure at 600 Torr total pressure in N2/O2 mixtures at 298 and 261 K and for both DMS and DMS-d6 at 240 K. Currently recommended rates are based on an empirical fit to a two-channel mechanism. This work shows that at low temperatures the currently recommended expression underestimates both the effective rate coefficient for reaction together with the branching ratio between addition and abstraction.