Effects of Self-Absorption on Rotational ``Temperatures'' of OH in Flames

Abstract

Penner's method of calculating effects of absorption on measured OH (²Σ⁺) rotational distributions has been applied to the R₂ branch and the results compared with intensity measurements of acetylene‐oxygen flames at atmospheric pressure. It is shown that distributions in the hot gases above the reaction zone are in agreement with calculated distributions and that for isothermal regions the method can give both emissivity and rotational ``temperature,'' even when there is appreciable self‐absorption. Measured intensities in the reaction zone indicate that there is a rotational ``temperature'' several hundred degrees in excess of the adiabatic temperature and that the ``temperature'' of the emitters is greater than that of the absorbers.