Multiphoton Ionization/Dissociation of Molecular Sulfur S2 in the UV Region

The multiphoton ionization/dissociation dynamics of molecular sulfur (S2) in the ultraviolet range of 205–300 nm is studied using velocity map ion imaging (VMI). In this one-color experiment, molecular sulfur (S2) is generated in a pulsed discharge and then photodissociated by UV radiation. At the three-photon level, superexcited states are accessed via two different resonant states: the B3Σu– (v′ = 8–11) valence states at the one-photon level and a Rydberg state at the two-photon level. Among the decay processes of these superexcited states, dissociation to electronically excited S atoms is dominant as compared to autoionization to ionic states S2+ (X2Πg) at wavelengths λ 11)) that dissociates to ionic products following one-photon absorption. This work also reveals many interesting features of S2 photodynamics compared to those of electronically analogous O2.