PHOTODISSOCIATION OF ACETYL-CHLORIDE - CL AND CH, QUANTUM YIELDS AND ENERGY-DISTRIBUTIONS

Jet cooled acetyl chloride is dissociated at 236 nm via excitation of the (1)[n, pi (C=O)] transition. Chlorine atom photofragments Cl(P-2( 3/2)) and Cl(P-2(1/2)) are detected using (2+1) multiphoton ionizatio n. The relative Cl yield phi*=[Cl*]/([Cl]+[Cl*]) is measured to be 0. 4+/-0.02, and the mean translational energy of the Cl atoms is 0.28+/- 0.02 eV. Methyl fragments are also detected following primary dissocia tion and the internal state distributions are probed using (2+1) multi photon ionization through the 4p(z) Rydberg state at 286 nm and the 3p (z) Rydberg state at 334 nm. The quantum yield for CH3 formation is es timated to be 28%, relative to the CH3 yield from methyl iodide photol ysis. A small fraction of the available energy is channeled into methy l fragment angular momentum as the rotational state distribution exten ds only to N''=5. Our results indicate that CH3CO, generated as a prim ary photoproduct in the dissociation of acetyl chloride, subsequently decomposes to produce CH3 and CO, Energetic constraints in the mechani sm of acetyl chloride dissociation are discussed.