Ba. Balko et al., THE 193 NM PHOTODISSOCIATION OF 1,1-DIFLUOROETHYLENE AND 1,2-DIFLUOROETHYLENE, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 101(36), 1997, pp. 6611-6618
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.