Application of RRKM theory to the chemical and thermal activation of ethyl radicals

The quantum statistical RRKM theory of unimolecular reactions has been applied to the decomposition of excited ethyl radicals. These radicals can be formed either by collisional activation in a thermal system or chemically by the addition of hydrogen atoms to ethylene molecules. The assessment of pertinent parameters has been based on an appraisal of theory and experiment. The pressure dependence of the rate constant for the chemical activation reaction was used to assist in the assignment of activated complex parameters. These parameters were varied until good agreement was obtained between the calculated pressure falloff and data from this laboratory for the ${\mathrm{H+C}}_2{\mathrm{H}}_4$ reaction. The final parametric assignments were then used in calculations at higher temperatures for comparison with the thermal decomposition data for ethyl radicals from other laboratories.