Temperature Determinations from Band Spectral Data

Abstract

A method of interpreting intensity distributions of lines in a band for determining the temperature of the emitter has been worked out which is independent of photometer calibration. The criterion used is the place in the band where adjacent lines of overlapping branches are of equal intensity, that is, the intersection of envelopes of the microphotometer records for the respective branches of a given band. The temperature is readily determined from graphs showing the temperature as a function of the $J$ values at which the simultaneous requirements of equality of intensity and equality of frequency are satisfied in a given pair of branches. The method has been applied to the (0,1), (0,2), (0,3) and (0,4) bands of the Angstrom system of CO excited in the electrodeless ring discharge, both at room temperature and within a furnace at 365°C. Comparison of thermometer indications with the temperatures obtained by this method indicates (a) that the rotational energy distributions are characteristic of the temperature of the gas in the source, and (b) that the electrodeless ring discharge is a low temperature source of spectra. The error of the new method under favorable conditions may be as small as 5 percent of the absolute temperature.