| The bulk of this work presents experimental and theoretical characterization of key intermediates on the O + allyl potential energy surface. The 193 nm photodissociation of epichlorohydrin, c-(H2COCH)CH2Cl, the intermediate corresponding to the oxygen atom adding across the middle and one terminal carbon atom to form an epoxide radical intermediate, INT2. Facile epoxide ring opening converts INT2 to INT1, where the oxygen atom is attached to a terminal carbon atom. Our experiments probe the carbon-hydrogen and carbon-carbon bond fission channels of this addition complex that result in complete reaction of all nascent INT1 radicals. In addition to finding that all INT1 radicals possess a enough vibrational energy to dissociate, our data supports the ground state radicals having large amounts of rotational energy. The C-C bond fission channels evidence strong forward-backward scattering, which is a result of the large rotation energy. The experimental (statistical transition state theory using barrier heights and single point energies from high-level electronic structure calculations) branching fractions are 18% (28%) to H + acrolein, 53% (60%) to HCO + ethene, 12% (6%) to C2H 3 + formaldehyde, and 17% (<2%) to HCCH + H3CO/H 2COH. The statistical transition state theory calculations predict 4% of the INT1 radicals are stable. Additionally, photoionization efficiency curves (with absolute photoionization cross sections) for ethene, HCO, C 2H3, and formaldehyde are derived. |
