THE 193 NM PHOTODISSOCIATION OF 1,1-DIFLUOROETHYLENE AND 1,2-DIFLUOROETHYLENE

The photodissociation of 1,1- and 1,2-difluoroethylene (DFE) at 193 nm was studied by measuring product translational energy distributions, P(E-T), for the various product channels. The P(E-T)'s are used to obt ain information on the exit barriers, product internal energy, transit ion states, and the stability of intermediates in many of these channe ls. Significant differences in the P(E-T)'s for three-centered elimina tion of HF to produce:C=CHF and four-centered elimination of HF to giv e HC=CF were observed. These were attributed to differences in the exi t barriers and transition states for the two types of elimination. Thi s is the first reported study of the three-and four-centered H-2 elimi nation pathways producing:C=CF2 and FC=CF, respectively. Both reaction s showed the presence of a small exit barrier. This work also gives th e first detailed description of the H and F atomic elimination channel s. The P(E-T) for primary H atom elimination indicates a simple bond r upture mechanism; the P(E-T) for secondary H atom elimination suggests that triplet product is formed. The P(E-T)'s for F atom elimination i ndicate that (CH)-C-.=CHF is more stable than (CF)-C-.=CH2. Where appr opriate, comparisons of the various DFE and ethylene photodissociation channels were made.