Rate constants, branching fractions, and energy disposal for the H+ClO and H+SF reactions

Abstract

The H+ClO and SF reactions have been isolated and studied by infrared chemiluminescence in a fast flow reactor. The OH product channel is favored over the HCl channel by a factor of 4.5 and the total rate constant is (7.7±1.9)×10−11 cm3 s−1 for the H+ClO reaction. Both sets of products are accessed from a bound singlet intermediate with HCl+O(3 P) formed by a singlet–triplet surface crossing in the exit channel; the energy disposal is 〈fV (OH)〉=0.45 and 〈fV (HCl)〉=0.31. The H+SF reaction gives only HF+S(3P), but the energy disposal differs dramatically from the HCl channel of the ClO reaction. This difference arises from changes in the thermochemistry, which result in an earlier crossing to the HSF triplet surface followed by release of repulsive energy as the HF separates from the S(3P) atom.