PHOTOINDUCED NEAR-ULTRAVIOLET 3 BODY DECAY OF PHOSGENE

Faced with the problem of underdetermined kinetic equations in analyzi ng momenta and kinetic energies of three body decay fragments, we foll owed two conceptually different paths in order to shed light on the dy namics of the process. One is based on the evaluation of the observed kinematic quantities after introduction of physically meaningful param eters for each type of decay: sequential, synchronously concerted, and asynchronously concerted mechanism. The other one is based on an info rmation theoretic approach, maximizing the entropy of the joint probab ility matrix containing the probabilities for coincidently realizing a ccessible sets of product states. The results obtained in both cases m atch remarkably well: No significant contribution of a molecular chann el, producing chlorine molecules, was found. Likewise, the generation of a stable chloroformyl radical had been ruled out in previous studie s, so that every dissociation process upon irradiation around 230 nm y ields three fragments: two chlorine atoms and a carbon monoxide molecu le. For this three body decay, the asynchronously concerted mechanism is the dominant dissociation channel, accounting for over 80% of the p roducts. The chlorine fragments move preferentially in the same direct ion, resulting in forward scattering of the carbon monoxide. A less ab undant decay channel is the synchronously concerted mechanism, in whic h the two bonds cleave in unison, and that accounts for the remaining products. The geometry of the decaying parent resembles the ground sta te equilibrium geometry with significant excitations of the COCl2 bend ing modes. For both mechanisms the CO fragments are generated with hig h internal excitation.