A LASER PHOTOLYSIS TIME-RESOLVED FOURIER-TRANSFORM INFRARED-EMISSION STUDY OF OH(X-(2)PI,-V) PRODUCED IN THE REACTION OF ALKYL RADICALS WITH O(P-3)

The emission spectra of vibrationally excited hydroxyl radical product s formed in the reactions of alkyl radicals with O(P-3) atoms are dete cted using a laser photolysis/time-resolved Fourier transform infrared spectroscopy technique. For the reaction between oxygen atoms and eth yl, the radicals are produced simultaneously by the 193 nm photolysis of the precursors SO2 and diethyl ketone, respectively. The observed i nitial OH(upsilon) product vibrational state distribution for the C2H5 + O(P-3) reaction is 0.18 +/- 0.03, 0.23 +/- 0.04, 0.29 +/- 0.05, 0.2 3 +/- 0.07, and 0.07 +/- 0.04 for upsilon = 1 to 5, respectively. The population inversion is best explained by a direct abstraction mechani sm for this radical-radical reaction. Vibrationally excited hydroxyl r adicals are also observed in the O + ethyl, O + n-propyl, and O + i-pr opyl reactions when using alkyl iodides as precursors of the alkyl rad icals, although quantitative detail is not obtained due to competing r eaction processes. (C) 1998 American Institute of Physics.