A LASER FLASH-PHOTOLYSIS, TIME-RESOLVED FOURIER-TRANSFORM INFRARED-EMISSION STUDY OF THE REACTION CL-]HCL(UPSILON)+C2H4(C2H5)

The atom-radical reaction Cl + C2H5 --> HCl(upsilon) + C2H4 is studied using laser flash photolysis, time-resolved Fourier transform infrare d emission spectroscopy and broad band infrared chemiluminescence. The Cl atoms and ethyl radicals are produced from a number of different p recursors using one or two lasers. The initial HCl vibrational distrib ution is determined to be HCl (upsilon=1/2/3/4=0.39 +/- 0.04/0.29 +/- 0.03/0.22 +/- 0.02/0.10 +/-0.02). The vibrational distribution is char acteristic of an addition-elimination mechanism and can be reproduced using modified statistical theories of energy partitioning within the [C2H5Cl] intermediate. The time evolution of the HCl(upsilon=4) emissi on is used to estimate a rate coefficient for this reaction of (3.0 +/ - 1.0) x 10(-10) cm3 molecule-1 s-1.