State Selectivity and Dynamics in Dissociative Electron Attachment to CF₃I Revealed through Velocity Slice Imaging

In light of its substantially more environmentally friendly nature, CF₃I is currently being considered as a replacement for the highly potent global-warming gas CF₄, which is used extensively in plasma processing. In this context, we have studied the electron-driven dissociation of CF₃I to form CF₃^- and I, and we compare this process to the corresponding photolysis channel. By using the velocity slice imaging (VSI) technique we can visualize the complete dynamics of this process and show that electron-driven dissociation proceeds from the same initial parent state as the corresponding photolysis process. However, in contrast to photolysis, which leads nearly exclusively to the ²P_1/2 excited state of iodine, electron-induced dissociation leads predominantly to the ²P_3/2 ground state. We believe that the changed spin state of the negative ion allows an adiabatic dissociation through a conical intersection, whereas this path is efficiently repressed by a required spin flip in the photolysis process.