15min:

L. R. BROCK AND ERIC A. ROHLFING, Combustion Research Facility, Sandia National Laboratories, Livermore, CA; B. MISCHLER, Paul Scherrer Institut, Ch-5232, Viligen PSI, Switzerland.

The ketenyl radical, HCCO, is widely recognized as a critical reaction intermediate in hydrocarbon combustion. In order to enable laser-based diagnostics of ketenyl in combustion and kinetics environments, we have examined the electronic spectroscopy of the B ² - X ²A" band system of H(D)CCO using laser-induced fluorescence in a free-jet environment. We obtain both vibronically resolved excitation spectra and fully rotationally resolved spectra for the origin band and for four bands terminating on levels of vibronic symmetry, which are assigned to the two pairs of states derived from one quantum of excitation in each of the Renner-Teller active modes, the CCO and CCH(D) bend. In addition to the Renner-Teller and spin-orbit couplings, there is substantial evidence for additional perturbations among the low-lying bending levels in the first excited state of ketenyl.