Isotope effects and excitation functions for the reactions of S(D)+H2, D2 and HD

Excitation functions for the title reactions were determined from 0.6 to 6 kcal/mol. Contrary to the analogous reaction of O( ¹D), it appears that the reaction of S( ¹D) proceeds solely through insertion over this energy range. Compared to other reactions, an intriguing H/D isotope effect was revealed. The propensity of the intramolecular H/D branching found under thermal conditions for A+HD reactions appears to be reverse for a supersonically cooled HD reagent. This finding implies that the reagent rotation could have profound influences on radical reactivity not only for an activated abstraction reaction, but for a barrierless inserted one.