Changes in infrared emission and absorption spectra of hot gases brought about by controlled variations of gas temperature profile were measured. Spectral emission-absorption temperatures were determined from the spectral data as a function of wavelength, using the Kirchhoff and Planck laws. These temperatures proved independent of wavelength for an isothermal profile, despite a large variation of absorptance with wavelength. For nonisothermal profiles, the emission-absorption temperature varied with wavelength in a characteristic manner for each profile. These results established more firmly the validity of the infrared emission-absorption technique of gas temperature measurement, and confirmed a previous hypothesis that the wavelength dependence of spectrally determined temperature, observed for most flames, is a temperature profile effect. The spectral emittance equation for a gas was formulated in terms of observable quantities for isothermal and nonisothermal cases, taking the spectrometer slit function into account.
© 1965 Optical Society of America
Original Manuscript: June 5, 1964
Published: February 1, 1965
Richard H. Tourin and Burton Krakow, "Applicability of Infrared Emission and Absorption Spectra to Determination of Hot Gas Temperature Profiles," Appl. Opt. 4, 237-242 (1965)