DISSOCIATION DYNAMICS OF CLONO2 AND RELATIVE CL AND CLO PRODUCT YIELDS FOLLOWING PHOTOEXCITATION AT 308 NM

Chlorine nitrate photolysis at 308 nm has been investigated with a mol ecular beam technique. Two primary decomposition pathways, leading to Cl + NO3 and ClO + NO2, were observed. The branching ratio between the se two respective channels was determined to be 0.67 +/- 0.06:0.33 +/- 0.06. This ratio is an upper limit because some of the ClO photoprodu cts may have undergone secondary photodissociation. The angular distri butions of the photoproducts with respect to the direction of polariza tion of the exciting light were anisotropic. The anisotropy parameters were beta = 0.5 +/- 0.2 for the Cl + NO3 channel and beta = 1.1 +/- 0 .2 for the ClO + NO2 channel, indicating that dissociation of ClONO2 b y either pathway occurs within a rotational period. Weak signal at mas s-to-charge ratios of 35 and 51, arising from products with laboratory velocities close to the beam velocity, was observed. While this signa l could result from statistical dissociation channels with a total rel ative yield of 0.07 or less, it is more likely attributable to product s from ClO secondary photodissociation or from dissociation of cluster s.