Emission and absorption of radiation by spectral lines with Doppler contour

Equations are developed for observable intensities in emission and absorption for spectral lines with Doppler contour. It is shown that the theoretical relations which are usually employed in estimating effective temperatures of internal energy states (a) require slight modifications when proper allowance is made for the shape of spectral lines, and (b) are not valid unless the product of spectral absorption coefficient and optical density is sufficiently small. Illustrative calculations on several spectral lines belonging to the (0,0) band of the 2Sigma-->2Pi band system of OH suggest that the conditions under which the basic relations hold are probably not satisfied for representative combustion flames