The ultraviolet photodissociation dynamics of 2-chloro-1,1-difluoroethylene

The rotational state distribution of HCl(upsilon'=0 and 1) produced in the 193 nm photodissociation of the title molecule was measured in a pulsed pump-and-probe experiment. The product state population was found to have a Boltzmann-like distribution, in agreement with a simple phase-space model. The photodissociation mechanism is proposed to be a three-center elimination of HCl to produce the F2C=C: carbene. The barrier for rearrangement of this fragment is believed to be very large, so that any energy released in the eventual isomerization step does not affect the HCl state distribution. These results support our explanation of the nonstatistical state distribution of HCl produced in the photodissociation of vinyl chloride and dichloroethylene. (C) 1997 American Institute of Physics.