Photodissociation and multiphoton dissociative ionization processes in CH3S2CH3 at 193 nm studied using velocity-map imaging

Dissociation and ionization processes in dimethyl disulfide, CH3S2CH3, induced by one- or two-photon absorption of 193 nm light, have been studied using velocity-map ion imaging. The analysis of the ion images of the CH3S2+, CH3S+, S2+, and S+ fragments has allowed the characterization of the scattering dynamics of some of the main photolysis and dissociative-ionization processes. In particular, the experiments corroborate the formation of electronically excited SCH3(2A1) products in the 193 nm photodissociation of dimethyl disulfide seen in earlier studies, and show that laser ionization provides a very sensitive method for their detection. The data have also allowed determination of the recoil energy and angular distributions of the CH3S2+ and CH3S+ products of the two-photon dissociative-ionization of the CH3S2CH3 molecule. The measured distributions for these products are consistent with the formation of a transient parent ion which dissociates after a substantial intramolecular rearrangement, possibly yielding the most stable isomeric forms of the fragments, namely CH2S2H+ and CH2SH+