PHOTODISSOCIATION OF TRANS-DICHLOROETHYLENE - STATE-RESOLVED SPEED AND ANGULAR-DISTRIBUTIONS OF CL ATOMS

The elimination of atomic chlorine in the ultraviolet photodissociation of trans-dichloroethylene was studied by measuring speed and angular distributions of Cl(P-2(j); J = 1/2, 3/2) atoms. Two components were observed in the translational energy distributions, similar to those observed by Umemoto ct al. using photofragment translational spectroscopy. One component has a strong anisotropy and a Gaussian-shaped translational energy distribution, while the other has a weak anisotropy and a Boltzmann-like distribution, The former is ascribed to rapid C-Cl bond rupture due to surface crossing between the (pi,pi(*)) and (n,sigma(*)) or (pi,sigma(*)) states, while the latter to thermal decomposition via internal conversion to the ground electronic state. The wavelength dependence and Cl-*/Cl branching ratios of the two dissociation channels were also investigated.