Cl-Loss Dynamics of Vinyl Chloride Cations in the B2A″ State: Role of the C2A′ State

The dissociative photoionization of vinyl chloride (C2H3Cl) in the 11.0–14.2 eV photon energy range was investigated using threshold photoelectron photoion coincidence (TPEPICO) velocity map imaging. Three electronic states, namely, A2A′, B2A″, and C2A′, of the C2H3Cl+ cation were prepared, and their dissociation dynamics were investigated. A unique fragment ion, C2H3+, was observed within the excitation energy range. TPEPICO three-dimensional time-sliced velocity map images of C2H3+ provided the kinetic energy release distributions (KERD) and anisotropy parameters in dissociation of internal-energy-selected C2H3Cl+ cations. At 13.14 eV, the total KERD showed a bimodal distribution consisting of Boltzmann- and Gaussian-type components, indicating a competition between statistical and non-statistical dissociation mechanisms. An additional Gaussian-type component was found in the KERD at 13.65 eV, a center of which was located at a lower kinetic energy. The overall dissociative photoionization mechanisms of...