Laser-induced fluorescence spectroscopy of the ketenyl radical

Abstract

Articles you may be interested inCross sections for rotational decoherence of perturbed nitrogen measured via decay of laser-induced alignmentWe report the first laser-induced fluorescence ͑LIF͒ excitation spectrum of the ketenyl radical, HCCO, which is produced by the 193 nm photolysis of ketene in a free jet expansion. A series of vibronic bands in the B 2 ⌸ -X 2 AЉ system are observed. The LIF band positions and rotational structures are in excellent agreement with those of a recent photofragment yield ͑PFY͒ spectrum ͓D. L. Osborn et al., J. Chem. Phys. ͑to be published͔͒ from the origin at 33 424 cm Ϫ1 to 35 100 cm Ϫ1 . At higher energies the LIF spectrum breaks off sharply due to a rapid increase in the rate of predissociation. The lifetime of the vibrationless level of the B state is less than 1 ns; the estimated quantum yield of fluorescence is ϳ10 Ϫ3 .

Ab initio investigation of the vibronic spectrum involving the two lowest-lying electronic states of HCCO

“…Osborn et al 9 assigned a band in their photofragment yield ͑PFY͒ spectrum to the electronic transition from the ground to the second excited state. Brock et al 10 discovered by means of laserinduced fluorescence ͑LIF͒ spectroscopy a hot band corresponding to a ground state bending mode of 494 cm Ϫ1 . Taylor and Neumark 11 observed photodetachment transitions from HCCO Ϫ to HCCO and obtained a vibrationally resolved spectrum for HCCO.…”

“…The ketenyl radical HCCO has been the subject at numerous kinetical, 1-3 spectroscopical, [4][5][6][7][8][9][10][11] and theoretical investigations, 2,12-15 because it is an important combustion intermediate in the oxidation of acetylene [16][17][18][19] and a species of considerable astrophysical interest. 20,21 On the basis of their microwave data Endo and Hirota 4 suggested a bent ground state geometry of HCCO.…”

State-selected imaging of HCCO radical photodissociation dynamics

“…The spectrum near the origin was examined in greater detail by Brock et al using laser-induced fluorescence and assigned to the B ͑ 2 ⌸͒-X ͑ 2 AЉ͒ bent-to-linear transition. 30 35 500 cm −1 or above, formation of ground state products came to dominate. As the excitation energy was further increased, two distinct components appeared in the translational enerrgy distributions.…”

“…6,30 It is the lower component of a RennerTeller pair, with the higher component showing a linear minimum. Both of these correlate along the HC-CO coordinate to ground state CH ͑ 2 ⌸͒ and CO products.…”

Examination of an Oscillating Flame in the Turbulent Flow Around a Bluff Body with Large Eddy Simulation Based on the Probability Density Function Method

“…All these measures are plotted in Fig.15 Reliable fluorescence imaging techniques already exist for the determination of the mole fraction of molecular oxygen [12,15]. Brock et al [6] have developed laser-induced fluorescence spectroscopy of the ketenyl radical. This enables the experimentalist to determine the product [O 2 ][HCCO] and test its application in similar flame configurations.…”