Photodissociation spectroscopy and dynamics of the HCCO free radical

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.474064· OSTI ID:508959

Osborn, D L; Mordaunt, D H; Choi, H; Bise, R T; Neumark, D M ^[1]; McMichael Rohlfing, C ^[2]

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1. Department of Chemistry, University of California, Berkeley, California, 94720 (United States)
2. Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969 (United States)

The photodissociation spectroscopy and dynamics of the HCCO radical have been investigated using fast radical beam photofragment translational spectroscopy. An electronic band with origin at 33424cm{sup {minus}1} has been identified. This band exhibits rotational resolution near the band origin, but the well-defined rovibronic structure is homogeneously broadened at higher photon energies. Based on the rotational structure this band is assigned to the {tilde B}{sup 2}{Pi}{l_arrow}{tilde X}{sup 2}A{sup {prime}{prime}} transition. Photofragment translational energy and angular distributions were obtained at several excitation energies. At excitation energies close to the origin, the excited, spin-forbidden CH(a{sup 4}{Sigma}{sup {minus}})+CO channel dominates, while the ground state CH(X{sup 2}{Pi})+CO channel is the major channel at higher photon energies. The translational energy distributions provide evidence of competition between intersystem crossing and internal conversion dissociation mechanisms, with some evidence for nonstatistical dynamics in the CH(X{sup 2}{Pi})+CO channel. This work yields an improved heat of formation for HCCO, {Delta}H{sub f,298}{sup 0}=1.83{plus_minus}0.03eV. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Lawrence Berkeley National Laboratory
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 508959
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 24 Vol. 106; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
COMBUSTION PRODUCTS
ELECTRONIC STRUCTURE
FORMATION HEAT
GROUND STATES
HYDROCARBONS
MOLECULAR BEAMS
ORGANIC COMPOUNDS
PHOTOLYSIS
POTENTIALS
RADICALS
ROTATIONAL STATES
ULTRAVIOLET SPECTRA
VIBRATIONAL STATES