Translational distributions of fragments produced in the photodissociation of vinyl fluoride at 157 nm

The photodissociation of vinyl fluoride following electronic excitation at 157 nm has been studied using the techniques of mass-resolved photofragment time-of-flight spectroscopy. HF elimination has been observed as the main primary dissociation process. This channel has a translational energy distribution peaked at around 20 kcal/mol, indicating that the reaction has a substantial exit barrier. We conclude that HF is mainly produced via four-center elimination. Other primary reactions have also been observed and are tentatively assigned as the CH bond rupture and H2 elimination processes. The mechanisms of the unimolecular reactions of vinyl fluoride are discussed on the basis of ab initio molecular orbital calculations.