Ion Imaging of the Photodissociation of Chlorine-Containing Molecules

The photodissociation dynamics of four chlorine-containing compounds was studied by the ion imaging technique. Two compounds, ClNO and (CH₃)₃COCl, exhibited strong anisotropy, and the kinetic energy distributions for Cl(²P_3/2) and Cl*(²P_1/2) were indistinguishable. For CCl₄ and SOCl₂ the kinetic energy distributions of Cl and Cl* were very different. In all cases most of the chlorine atoms were released in their ground ²P_3/2 state. A general explanation is given based on these data and those of others. The process is described in terms of three states whose energies are in the following order:? the ground state, a state correlating with Cl*, and a state correlating with Cl. Sooner or later the Cl state must cross the Cl* state. If the crossing is sooner, i.e. in the Franck?Condon region, Cl and Cl* will have different translational energy distributions. If the crossing is later, i.e. at long distances, Cl and Cl* will have descended a repulsive surface and reached their asymptotic and nearly equal kinetic energies.