Abstract : In order to compute the emissivity of a diatomic gas, a simplified model of a diatomic molecule is assumed: an anharmonic oscillator with the first approximation to the vibration-rotation interaction. For a given band, the frequency of emitted radiation is expressed as a quadratic function of the quantum number m, which is solved to express m as a function of omega. This expression is substituted for m in the equations used for computing the average line intensity and average line spacing. By applying the random Elsasser model to the fundamental and superposed higher order bands, closed-form solutions are obtained for the emissivity as a function of omega for certain limiting cases. Experimental data, where available, are used for the line widths and total absorption of the bands. The harmonic oscillator approximation is used to estimate strengths of higher order bands for which experimental data are not available. This analysis is applied to HCl, HF, CO, and NO for temperatures ranging from 300 to 7000 deg K.
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