Probing Ultrafast Dissociation Dynamics of Pentafluorobenzene Cation (C₆F₅H⁺) with Electrons

Real-time observation of a structural change of photoexcited molecular ion is important to understand the fundamental reaction mechanism. Here, we use mega-electronvolt ultrafast electron diffraction technique (MeV-UED) to directly construct a molecular movie of photogenerated pentafluorobenznen cation. The molecular cation was produced by multiphoton ionization of C₆F₅H at 269 nm. This cation dissociates into fragment ions within ~10 ps time scale through statistical internal energy redistribution prior to the following bond dissociaiton and ring opening. Parir distribution function (PDF) analysis allows us to pin down the specific chemical bond dissociaiton process in this unimolecular dynamics.