Primary processes involved in the photodissociation of saturated hydrocarbons at 157 nm

摘要

Much speculation exists regarding the primary processes involved in the unimolecular dissociation of saturated hydrocarbons dating back to the early 1960s. Previous experiments typically involved photolysis of a hydrocarbon with subsequent detection of products by mass spectrometry. The conditions of the experiments (i.e., high pressure) led to uncertainty as to which of the detected products were primary products resulting from the unimolecular decomposition of the hydrocarbon of interest. Using the technique of photofragmentation translational spectroscopy (PTS), we have determined the primary and secondary photodissociation channels of cyclopropane, n-propane, n-butane, and isobutane at 157 nm. The PTS technique involves the use of a molecular beam which inherently gives collision free conditions, ideal for the study of unimolecular photodissociation processes.