Kinetics of the reactions of mercapto radicals with nitrogen dioxide and oxygen

The SH + NO/sub 2/ reaction rate constant was measured by monitoring SH concentrations with long-path optical absorption at 324 nm in a laser photolysis system. At 298 K the rate constant was found to be (4.8 +/- 1.0) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/. An upper limit of 4 x 10/sup -19/ cm/sup 3/ molecule/sup -1/ s/sup -1/ was inferred for the SH + O/sub 2/ reaction, indicating that the atmospheric oxidation of the SH radical may occur via reaction with species such as NO/sub 2/ and O/sub 3/.