Thermal decomposition pathways of alkyl radicals by photoelectron spectroscopy. Application to cyclopentyl and cyclohexyl radicals

Thermal unimolecular decompositions of cyclopentyl and cyclohexyl free radicals have been observed in the heated inlet of a photoelectron spectrometer. Experiments have been performed over a range of temperatures, and mechanisms consistent with the data are presented. The results for cyclopentyl radical are in good agreement with those obtained by using other techniques, while the mechanism proposed for cyclohexyl radical decomposition is at variance with an earlier study. Arguments supporting conclusions drawn from the photoelectron experiments are given. The present work serves to demonstrate the utility of photoelectron spectroscopy for the study of reactions involving short-lived intermediates. The advantages and limitations of the technique in comparison to more commonly used methods are discussed