OBSERVATION NOTE ON SATURATION BEHAVIOR OF THE FLUORESCENCE EXCITATION SPECTRUM OF OH IN A FLAME

During a series of temperature and OH concentration measurements in a methane/air flame, we found that the output spectral linewidth of our dye laser displays a dependence upon the pumping power. This effect is superimposed on the normal saturation broadening of the fluorescence spectrum. In this note, we discuss our results concerning spectral laser bandwidth measurement for two different laser working conditions. The effects upon saturation curves and saturation broadening of OH in a methane/air flame are also reported. It is shown that whenever accurate measurements are required, it is worthwhile to consider this effect, especially when power variations can occur.