Pulsewidth dependence of ozone interference in the laser fluorescence measurement of OH in the atmosphere

By varying the pulsewidth of the output from two dye lasers, we have verified experimentally that the steady-state interference level of OH due to laser-induced dissociation of ozone decreases linearly with decreasing pulsewidth of the exciting radiation. At low pressures, further reduction in the interference level due to the transient nature of OH formation processes was also observed. These results should greatly facilitate measurements of OH concentrations in the atmosphere.