Measurement and Analysis of OH Emission Spectra Following Laser-Induced Optical Breakdown in Air

The measured emission spectra of the OH radical subsequent to laser-induced optical breakdown in air are analyzed to infer spectroscopic temperature and species number density. Emissions from the UV A2 (sigma)+ (longrightarrow) X2 IIi transition dominate the spectra in the wavelength range of 306 -322 nm and for time delays from the optical breakdown of 30 -300 (mu)s. Contributions from other species to the recorded OH emission spectra were also investigated for spectroscopic temperature measurements in the range of 2000 -6000 K and for OH number densities in the range of 10^(14) -2 *1016 cm^-3 . Monte Carlo simulations are applied to estimate errors in the analysis of the hydroxyl spectra.