H-Atom Product Channels in the Ultraviolet Photodissociation of the 2-Propenyl Radical

The H-atom product channels in the ultraviolet photodissociation of 2-propenyl (CH2CCH3) radical were investigated in the wavelength region of 224-248 nm using photofragment translational spectroscopy. The CH2CCH3 radicals were generated by 193-nm photodissociation of 2-chloropropene and 2-bromopropene precursors. The H-atom photofragment yield spectra from both precursors revealed a broad feature peaking near 232 nm. The translational energy distributions of the H + C3H4 products peaked around 7-8 kcal/mol and extended close to the maximum excess energy. The fraction of the total available energy released as products' translation was nearly a constant (~ 0.16 using the 2-chloropropene precursor and ~ 0.18 using the 2-bromopropene precursor) in the wavelength range of 224-248 nm. The angular distribution of the H-atom product was isotropic. Quasi-classical trajectory (QCT) calculations were performed on the ground-state potential energy surface of CH2CCH3 for its decomposition at a 124 kcal/mol excitation...