THE $\tilde{A}\ ^{3}\Pi_{i} – \tilde{X}\ ^{3}\Sigma^{-}$ SYSTEM OF CCO

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Ohio State University

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$C_{2}O$ is a molecular species of importance in combustion $chemistry^{1}$ which has not been well characterized with respect to production mechanisms or reactions leading to its disappearance. In an attempt to determine its production and disappearance mechanisms the molecule is being studied by laser induced fluorescence. Ground state $\tilde{X} ^{3}\Sigma^{-}, C_{2}O$ is produced by the laser pohotolysis at 266nm of carbon suboxide, $C_{3}O_{2}$. The $C_{2}O$ fragments are probed by a previously unreported laser induced fluorescence on the $\tilde{A} ^{3}\Pi_{i} \rightarrow \tilde{X} ^{3}\Sigma^{-}$ transition in the 620-670nm region. Under collision-free conditions an extremely complex fluorescence excitation spectrum is observed which is typical of very hot primary fragments. When the nacently produced $C_{2}O$ fragments are thermalized by buffer gas collisions prior to probing, the excitation spectrum collapses to the previously assigned absorption $spectra^{2}$ of CCO. The fluorescence spectrum, fluorescence excitation spectra and excited state lifetimes and bimolecular quenching rates will be reported. In addition measurements are underway to characterize reactions of $C_{2}O$ expected to be of importance in combustion.


$^{*}$National Research Council/Naval Research Laboratory Postdoctoral Research Associates. $^{1}$ V.M. Donnelly and L. Pasternack, Chem. Phys., in press. $^{2}$ C. Devillers and D.A. Ramsay, Can. J. Phys., 49, 2839 (1971)
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