Check of OH rotational temperature using an interferometric method

This paper presents an interferometric method used to check the rotational temperature of the OH free radical obtained using emission spectroscopy. The temperature is extracted from an interferogram via the phase shifting introduced by the refractive index of the studied medium. The refractive index is related to the temperature through the Gladstone-Dale equation and the ideal gas law. The method is tested on the laminar premixed flame of an oxy-acetylene burner and on the laminar plume of a dc argon plasma torch. The results obtained are compared with those obtained from the UV OH band at 306.357 nm (transition A(2)Sigma, nu = 0 --> X(2)Pi, nu' = 0) by emission spectroscopy using the Boltzmann plot method and using a method based on numerical simulated spectra with the amplitude ratios of groups of unresolved rotational lines.