Laser-induced fluorescence from the predissociating formyl radical. 1. Mechanism for the predissociation of the A sup 2 A double prime state

Journal Article · Thu Feb 23 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100341a026· OSTI ID:5061655

Rumbles, G; Valentini, J J; Stone, B M; Lee, E K.C. ^[1]

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1. Univ. of California, Irvine (USA)

Fluorescence excitation spectra of the HCO {tilde A}(0,11{degree},0)-{tilde X}(0,0{sup 1},0) and {tilde A}(0,9{degree},0)-{tilde X}(0,0{sup 1},0) transitions and the DCO {tilde A}-(0,15{degree},0)-{tilde X}(0,0{sup 1},0) transition are reported. Spectral simulations of each vibronic band show that all rotational transitions are lifetime broadened, with rotational line widths of {approx}0.5 and {approx}0.8 cm{sup {minus}1} for HCO and DCO, respectively. These values are constant up to N{prime} {approx} 10 and then increase with an N{prime}{sup 2}(N{prime} + 1){sup 2} dependence. The lifetime-broadening mechanism, which is nonradiative in nature, is due to predissociation to form H(D) + CO. The increase in line width is accompanied therefore by a reduction in fluorescence intensity. The origin of the homogeneous electronic predissociation mechanism at low N{prime} is unknown since no explanation for such a process currently exists. The N{prime}{sup 2}(N{prime} + 1){sup 2} dependence strongly implies K-type resonance as the dominant process for the heterogeneous electronic predissociation at high N{prime}. The more facile rate of predissociation of DCO over HCO precludes quantum mechanical tunneling as an explanation of the observed line-width and intensity dependence on N{prime}.

• OSTI ID: 5061655
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:4; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALDEHYDES
CHEMICAL REACTIONS
DATA
DEUTERIUM COMPOUNDS
DISSOCIATION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
FLUORESCENCE
FORMALDEHYDE
HYDROGEN COMPOUNDS
INFORMATION
LASERS
LIFETIME
LINE BROADENING
LUMINESCENCE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PREDISSOCIATION
RADICALS