Knowledge Bank

Time resolved detection of the formyl radical, HCO, has been achieved by means of laser resonance absorption. Photolysis of formaldehyde by the 308 nm output of a XeCl excimer laser ($\sim 30$ mJ/pulse, 20 nsec FWHM) produces transient concentrations of the radical which are probed by a single-frequency $Ar+$ pumped CW dye laser ($\Delta \nu -50$ MHz) tuned to the R(11) line of the $A~2A\prime$ (0, 9, 0) $\to X~2A\prime \prime$ (0, 0, 0) transition of HCO near 6138.0 {\AA}. Rate constants for the radical - radical H + HCO and HCO + HCO reactions of importance to combustion kinetics have been measured in preliminary studies. Further application of the technique to this and other systems will be discussed. The authors would like to acknowledge the support of the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract No. W-7405-Eng-48.