Kinetic spectroscopy using a color center laser

Abstract

Infrared kinetic spectroscopy is being developed using a pulsed excimer laser for ultraviolet photolysis and a color center laser spectrometer as an infrared probe in the 2.3–3.0-μm region. Sub­microsecond time resolution is possible with the 14-ns excimer laser pulses and the InSb detectors currently employed. Previous work on the Br, OH, and NH2 radicals has led to the development of three monitoring schemes based on the use of either balanced detectors, magnetic rotation, or short-time monitoring. Kinetic studies of the NH2 + NO reaction have measured the branching ratio of the two primary product channels by monitoring a number of precursors and products. Current work on the C2H radical produced by photolysis of acetylene has indicated an ~ 1-μs lifetime for this radical, demonstrating the ability to detect short-lived species. Other work includes the production of highly reactive O(1D) atoms by the photolysis of O3, providing a method for generating free radicals from stable molecules by hydrogen atom abstraction. Additional studies on the spectroscopy and kinetics of other free radicals are discussed.