Rapid-tuning frequency-doubled ring dye laser for high resolution absorption spectroscopy in shock-heated gases

A commercial ring-dye laser has been modified to increase the instrument's single mode tuning rate and to extend its operating wavelength range through the UV band, through the use of second harmonic generation (SHG). The modified ring-dye laser was used to make line shape measurements of the OH molecule, following shock waves generated in a shock tube. A single absorption line of OH was investigated behind an incident shock wave in an initially stoichoimetric mixture of H2 and O2, diluted at a ratio of 1:100 in argon. In experiments conducted over a range of pressures (0.38-1.31 atm), and temperatures (1498-2574 K), Voight profiles of different levels of collisional broadening were generated and were found to be in fair agreement with previous experiments with similar gas mixtures. A diagram of the ring dye laser and a schematic drawing of the shock tube experiment are provided.