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, Journal Name: Journal of Chemical Physics Journal Issue: 4 Vol. 136; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Photodissociation dynamics of the phenyl radical via photofragment translational spectroscopy
Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
ANGULAR DISTRIBUTION
DISSOCIATION
ENERGY SPECTRA
GROUND STATES
INTERNAL CONVERSION
ORGANIC COMPOUNDS
PEAKS
PHENYL RADICALS
PHOTOIONIZATION
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
RYDBERG STATES