Abstract

A new laser-based chemical kinetics technique has been demonstrated in studies of reactions of the hydroxyl radical with prototype hydrocarbon fuel molecules. A schematic diagram of the experimental apparatus is shown in Fig. 1. Following reaction initiation by 193-nm photolysis of N₂O in N₂O-H₂O-He-hydrocarbon mixtures, time-resolved OH concentration profiles were measured using a highly sensitive quasi-cw laser-induced fluorescence method. The visible output of a synchronously pumped dye laser, a train of pulses of 3-6-nJ energy, 8-10-psec duration, and ~50-GHz spectral bandwidth at a repetition rate of 246 MHz, was frequency-doubled with a temperature-tuned D-ADA crystal. Mounting the crystal oven assembly on a short-stroke oscillator stage minimized damage and phase mismatch within the crystal from local heating by the focused beam.

© 1983 Optical Society of America