Reactions of OH and OD radicals with ethanethiol and diethylsulfide: Branching ratio and vibrational energy disposal for the product water molecules

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Reactions of OH and OD radicals with C 2 H 5 SH and (C 2 H 5 ) 2 S were studied by Fourier-transform infrared emission spectroscopy of the water product molecules from a fast-flow reactor. Vibrational excitation of the H 2 O, HOD and D 2 O product molecules was determined by computer modeling of the chemiluminescence spectra. Spectra of the abstraction of H-atom from the ethyl group (C-H) and sulfur atom (S-D) were separated using deuterated reactant, C 2 H 5 SD. The branching ratio was found to be 0.24 ± 0.05 (C-H):0.76 (S-D) both for OH and OD reactants. For the OH + C 2 H 5 SH reaction the branching fraction for the (C-H) channel of 0.25 ± 0.06 was obtained. Vibrational energy disposal for S-H abstraction is similar to that for the reaction with CH 3 SH, whereas abstraction from the ethyl group demonstrates higher bending excitation than abstraction from the methyl group of CH 3 SH. A similar trend was found for abstraction from the ethyl and methyl groups of (C 2 H 5 ) 2 S and CH 3 SCH 3 .