Secondary decomposition of C3H5 radicals formed by the photodissociation of 2-bromopropene

The photodissociation of 2-bromopropene at 193 nm produces C(3)H(5) radicals with a distribution of internal energies that spans the threshold for the secondary decomposition of the 2-propenyl radicals into C(3)H(4)+H. Just above this threshold, the decomposition rate is on the nanosecond time scale, and in the present study, time-resolved velocity-map ion imaging is used to gain insight into this process. The results provide information on the energy dependence of the secondary dissociation process. In addition, comparison of the results with theoretical predictions of the energy dependence of the dissociation rate provides information on the branching between fragment rotational and vibrational energies in the primary photodissociation process.