Reaction of OH with dimethyl sulfide (DMS) .1. Equilibrium constant for OH+DMS reaction and the kinetics of the OH center dot DMS+O-2 reaction

The formation of a weakly bound adduct in the reaction of OH with DMS-d(6) was observed between 217 and 240 K using the technique of pulsed laser photolysis/pulsed laser-induced fluorescence. The equilibrium constant for this process, OH + DMS-d(6) <----> OH . DMS-d(6), was measured as a function of temperature. The bond strength of this adduct was determined to be 10.7 +/- 2.5 kcal mol(-1). The weakly bound adduct was observed to react rapidly with O-2. The rate constant for the reaction OH . DMS-d(6) + O-2 --> products was determined to be (1.00 +/- 0.33) x 10(-12) cm(3) molecules(-1) s(-1), independent of pressure and temperature. The atmospheric implications of the formation of this adduct and its reaction with O-2 to the mechanism of DMS oxidation in the atmosphere are discussed.