Low energy electron collisions in H2S and H2Se: Structure in dissociative attachment cross-sections

Dissociative electron attachment between 0 and 4 eV has been investigated in hydrogen sulfide and hydrogen selenide with an improved electron resolution (0.040 eV). HS− and HSe− cross-sections versus electron energy present vertical onsets revealing that the potential surfaces of the resonances which are reached around 2 eV are bound. A well-developed and intriguing structure is observed in HS−, S−, HSe− and Se− cross-sections. It could reveal interferences due to an attractive resonance having a lifetime of the order of one vibrational period. The strong similarity between the anion behaviour in H2S and H2Se is in contrast with H2O where no dissociative attachment process occurs in this energy range.