Temperature measurements by ultraviolet filtered Rayleigh scattering usinga mercury filter

We report the development of Ultraviolet Filtered Rayleigh Scattering (UV F RS) as a diagnostic tool for measurements of gas properties. ri frequency t ripled, narrow linewidth, Ti:sapphire laser illuminates a sample, and Rayle igh scattered light is imaged through a mercury vapor absorption filter. Th e strong absorption of the filter may be used to suppress elastic backgroun d. Tuning the laser through the absorption notch of the filter is a means o f probing the scattering line shape, which contains temperature information . Temperature measurements of air are shown to have uncertainties of less t han 3%, whereas measurements of a weakly ionized discharge have uncertainti es of less than 4%. An enhanced scattering cross section as well as nearly ideal filter properties lead to temperature sensitivities for the mercury f ilter in the ultraviolet which are comparable to those available with an io dine filter in the visible. The absorption far the mercury filter is modele d to be at least 5 orders of magnitude higher than for the iodine filter, m eaning that stronger background suppression may be achieved.