Ultraviolet photodissociation dynamics of the phenyl radical
- Department of Chemistry, University of California at Riverside, Riverside, California 92521 (United States)
- Department of Chemistry and Biochemistry, California State University, Long Beach, Long Beach, California 90840 (United States)
Ultraviolet (UV) photodissociation dynamics of jet-cooled phenyl radicals (C{sub 6}H{sub 5} and C{sub 6}D{sub 5}) are studied in the photolysis wavelength region of 215-268 nm using high-n Rydberg atom time-of-flight and resonance enhanced multiphoton ionization techniques. The phenyl radicals are produced from 193-nm photolysis of chlorobenzene and bromobenzene precursors. The H-atom photofragment yield spectra have a broad peak centered around 235 nm and are in good agreement with the UV absorption spectra of phenyl. The H + C{sub 6}H{sub 4} product translational energy distributions, P(E{sub T})'s, peak near {approx}7 kcal/mol, and the fraction of average translational energy in the total excess energy, , is in the range of 0.20-0.35 from 215 to 268 nm. The H-atom product angular distribution is isotropic. The dissociation rates are in the range of 10{sup 7}-10{sup 8} s{sup -1} with internal energy from 30 to 46 kcal/mol above the threshold of the lowest energy channel H +o-C{sub 6}H{sub 4} (ortho-benzyne), comparable with the rates from the Rice-Ramsperger-Kassel-Marcus theory. The results from the fully deuterated phenyl radical are identical. The dissociation mechanism is consistent with production of H +o-C{sub 6}H{sub 4}, as the main channel from unimolecular decomposition of the ground electronic state phenyl radical following internal conversion of the electronically excited state.
- OSTI ID:
- 22047163
- Journal Information:
- Journal of Chemical Physics, Vol. 136, Issue 4; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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