Kinetic spectroscopy of transient species using color center lasers

A versatile and sensitive method of kinetic spectroscopy for the near infrared region has been developed. The system uses a computer controlled color center to investigate the high resolution infrared absorption spectra of radicals created by ArF excimer laser flash photolysis. A number of experimental schemes were investigated to determine the optimum operating conditions, and several techniques for sensitivity enhancement were applied in an effort to improve the sensitivity of the system. Varying degrees of success resulted from these investigations. The Br atom was the principle radical studied in our kinetic spectroscopy system. Relative absorptions as loir as .8% were observed. The best spectra of this radical were obtained using a collinear arrangement of the excimer and infrared beams. This arrangement is most desirable when considering the wide range of absorption coefficients of precursors in the ultraviolet region is considered. Other radicals studied include the NH^ and OH radicals