Detection of free radicals by an intracavity dye laser technique

Abstract

A new technique for the detection of free radicals inside the cavity of a dye laser is described. This intracavity absorption phenomenon has two important advantages: (1) It has the potential for quantitative detection suitable for kinetic studies of transient chemical species and (2) It has a high degree of sensitivity. In the present work, the technique is shown to be at least as sensitive as, and most probably several orders of magnitude more sensitive than, previous methods for the detection of transients. It is presently a powerful tool for obtaining high resolution absorption spectra as well as obtaining precise information about the energy distribution of transient species produced photolytically or kinetically. Spectra for both NH₂ and HCO (produced flash photolytically) are presented.