Avoided curve crossing between the A₁ and B₁ states in CF₂Br₂ photolysis at 234 and 265 nm

The photodissociation dynamics of CF₂Br₂ has been studied using a two-dimensional photofragment ion image technique for the two excitation wavelengths 234 and 265 nm. At 234 nm, three dissociation channels, i.e., the radical CF₂Br + Br (²P_J) (J = 1/2, 3/2), the three-body CF₂ + 2Br (²P_J) (J = 1/2 3/2), and the molecular elimination channel CF₂ + Br₂, were observed with quantum yields of 0.84, 0.15, and trace, respectively. The difference between β (CF₂Br + Br (²P_3/2)) = 0.65 and β (CF₂Br + Br (²P_1/2)) = 0.80 suggests that the excited A₁ and B₁ states are strongly correlated by avoided curve crossing with a probability of 0.78. At 265 nm, the radical channel, the observed major primary dissociation channel, shows several components due to the transition close to the curve crossing point. On the basis of observations at both wavelengths, we have proposed a photodissociation dynamics model of CF₂Br₂ after A-band excitation.