The S −-H 2 collision system revisited

Abstract

It was found that the experimental results on the S −-H 2 collisional system previously published were affected at low collision energy by an experimental artefact. The correction primarily concerns the shape of the angular distributions of the three competing channels: simple detachment, reactive detachment and reactive charge transfer. The main conclusion of the previous paper stays unaffected, namely that, as for halide-H 2 systems, the trajectories leading at low collision energy to these three channels have a common path in the reaqctive SH-H − “valley” after an adiabatic passage through the crossing seam between the two S −HH and SHH − surfaces (diabatic with regard to the active electron). This conclusion is now reinforced in the light of the newly measured angular distributions obtained for the three channels. Their evolution with collision energy implies the existence of a unique short lived SH − 2 species explored by three types of trajectories leading to R, RD and SD channels. The role of the intermediate complex (SHH) − is investigated using a combination of the symmetric top model and the oscillating complex model.