Thermal Generation and Spectrometric Measurement of Ba and Ba+ in a Hot Flame

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Abstract
The object of this program was formulation and laboratory study of a combustion system whose products contain both neutral (Ba0) atoms and Ba+ ions. The system consists of tetracyanoethylene, hexanitroethane, and barium peroxide, all solids at room temperature. In a series of digital‐computer calculations, a mixture containing 8.0% BaO2, 52.6% C2(NO2)6, and 39.4% C2(CN)4 by weight was found suitable and chosen for experimental work. The calculated extent of ionization of barium in that mixture is 7.9%, at the adiabatic flame temperature of 3780°K. The mixture was prepared and pressed into strands of 1.65 g/cc density; its stability, sensitivity, and burning rate were studied. Flame spectrometry of the mixture yields line‐intensity temperature of 3310±50°K. The experimental extent of ionization of barium, determined by the relative intensities of the Ba+ and Ba0 lines, is 9.0%. The calculated equilibrium ionization at 3310°K is only 2.2%. The discrepancy between the measured and calculated degrees of ionization is ascribed to incomplete combustion of electron‐absorbing species, especially those containing the CN radical, which promote ionization of barium. Relevance of these laboratory studies to the performance of a scaled‐up burner releasing gaseous barium in the upper atmosphere is briefly discussed.

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