Infrared chemiluminescence studies of the reaction of fluorine atoms with monosubstituted ethylene compounds

The technique of arrested relaxation infrared chemiluminescence has been utilized for the observation of emission from the polyatomic substitution products of fluorine atom reactions with ethylene, propene, vinyl chloride, and vinyl bromide. A new apparatus for performing such experiments is described. The entire apparatus, including the scanning Michelson interferometer used in obtaining the emission spectra, is cooled to liquid nitrogen temperatures or lower. The resulting improvement in signal to noise ratio allows emission spectra to be recorded down to frequencies as low as 720 cm−1. Analysis of the chemiluminescence data allows the determination of the partitioning of reaction energy over the product vibrational modes. The results indicate statistical partitioning occurs for the vinyl chloride and bromide reactions, while the ethylene and propene reactions exhibit nonstatistical partitioning. The difference in energy partitioning for these reactions is attributed to the existence of a potential energy barrier in the exit channel for the latter two reactions, while no such barrier exists for the former reactions.