Temperature-Dependent Kinetic Study of the Reactions of Hydrogen Atoms with HS and CHS.

A discharge-flow reactor combined with modulated molecular beam mass spectrometry technique was employed to determine the rate constants of H-atom reactions with hydrogen sulfide and thiirane. The rate constants for both reactions were determined at a total pressure of 2 Torr from 220 to 950 K under pseudo-first-order conditions by monitoring either consumption of H atoms in excess of HS (CHS) or the molecular species in excess of atomic hydrogen. For H + HS reaction, a suggested previously strong curvature of the Arrhenius plot was confirmed: = 8.7 × 10 × (/298) × exp(-125/) cm molecule s with a conservative uncertainty of 15% at all temperatures. Non-Arrhenius behavior was also observed for the reaction of H-atom with CHS, with the experimental rate constant data being best fitted to a sum of two exponential functions: = 1.85 × 10 exp(-1410/) + 4.17 × 10 exp(-242/) cm molecule s with an independent of temperature uncertainty of 15%.