Journal of Physical Chemistry, Vol.99, No.42, 15400-15409, 1995
UV Photodissociation Dynamics of Single-Carbon Freons and Related Molecules
The UV photodissociation dynamics of CFCl3, CF2Cl2, CHCl3, CCl4, and CFBr3 were studied using photofragment translation energy spectroscopy with a linearly polarized dissociation laser at 193 and 248 nm wavelengths. Measurement of the partitioning of energy between translation and the various internal degrees of freedom and subsequent comparison of the experimental results with simple models revealed that these dissociations are direct and that the resulting polyatomic photofragments are highly excited. Measurement of the sign of the angular anisotropy of the photofragment flux with respect to the laser electric field vector defines the orientation of the electronic transition dipole in the molecule of interest and therefore yields information about the symmetry of the dissociative excited electronic state. We infer that all of the molecules dissociate from degenerate electronic states and that the degeneracy is lifted in several instances, either through a Jahn-Teller distortion of the electronic state or through dynamical coupling of angular momenta in the reactants and products.
Keywords:PHOTOFRAGMENT TRANSLATIONAL SPECTROSCOPY;193 NM;NO2 PHOTODISSOCIATION;248 NM;PHOTOLYSIS;CH3;CHLOROFLUOROMETHANES;DISTRIBUTIONS;DISSOCIATION;EXCITATION