Ion-Pair Dissociation Dynamics of SO2 in the Photon Energy Range 14.87−15.15 eV

Abstract

The ion-pair dissociation dynamics of SO(2) → SO(+) (X(2)Π,υ) + O(-) ((2)P(J)) in the excitation energy range 14.87-15.15 eV has been studied using the tunable XUV laser and velocity map imaging method. The O(-) yield spectrum, the translational energy distributions, and the angular distributions of the photofragments have been measured. The electronic structures and selected cuts of potential energy surfaces for the ion-pair states have been calculated by employing the quantum chemistry calculation method at the CASSCF/6-311++g** level. The equilibrium structures of the six ion-pair states all have linear geometries. An orbital correlation diagram was drawn to illustrate the ion-pair dissociation mechanism. Combining the experimental and theoretical results, it is concluded that the ion-pair dissociation takes place mainly via the predissociation of Rydberg states (1)A(1) [(C(2)B(1))4db(1)] and (1)A(1) [(D(2)A(1))4sa(1)]. The experimental results confirm the previous theoretical calculation results about the symmetry assignments for the energy sequence of SO(2)(+) as C((2)B(1)) < D((2)A(1)).