REACTION OF OH WITH DIMETHYL SULFIDE (DMS) .1. EQUILIBRIUM-CONSTANT FOR OH-CENTER-DOT-DMS+O-2 REACTION(DMS REACTION AND THE KINETICS OF THEOH)

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 co nstant for this process, OH + DMS-d(6) <----> OH . DMS-d(6), was measu red 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 w as observed to react rapidly with O-2. The rate constant for the react ion 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 t emperature. The atmospheric implications of the formation of this addu ct and its reaction with O-2 to the mechanism of DMS oxidation in the atmosphere are discussed.