The pulsed laser photolysis-pulsed laser-induced fluorescence technique has been employed to study the kinetics of OH reactions with CH3SH (k1) and CD3SH (k2) in N2, air, and O2 buffer gases. We find that k1 and k2 are independent of O2 concentration. Measured k1 values are in excellent agreement with previous flash photolysis-resonance fluorescence studies, all of which employed reaction mixtures containing no O2. However, the observation of no O2 dependence is in marked disagreement with a number of relative rate studies where NOx-containing species were employed as photolytic precursors for OH and olefins were used as the reference compound. k2 is found to be ∼13% slower than k1, suggesting the occurrence of a minor methyl hydrogen abstraction channel. In the course of investigating complications which result from photolysis of the mercaptan reactants, we found that 266-nm photolysis of either CH3SH or CD3SH in the presence of O2 (but in the absence of other OH photolytic precursors) results in production of OH.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry