Crossed beam investigations of the reaction dynamics of O(3P) with allyl radical, C3H5

The reaction of ground-state atomic oxygen (O(P-3)) with allyl radical (C3H5) was investigated in the crossed beam configuration. O(P-3) and C3H5 were generated by the photodissociation of NO2 and the supersonic flash pyrolysis of allyl iodide, respectively. The nascent internal distributions of the OH(X(2)Pi : v(')=0,1) reaction product from the newly observed channel of O(P-3)+C3H5-->C3H4+OH were probed by laser induced fluorescence (LIF) spectroscopy. The distributions showed significant excitations with an unusual bimodal feature: the low and high rotational components without spin-orbit and Lambda-doublet propensities in the ground and first excited vibrational states. On the basis of population analysis and comparison with the ab initio and statistical calculations, the experimental distributions are estimated to be totally non-statistical and suggest that the dynamics of the reaction might be described by two competing mechanisms: a major direct abstraction process and an indirect short-lived addition-complex forming process. (C) 2002 American Institute of Physics.