THE LUMINOUS MANTLE OF FUEL-RICH OXYACETYLENE FLAMES: I. SPECTROSCOPIC TEMPERATURE MEASUREMENTS

Abstract

The luminous mantle of fuel-rich oxyacetylene flames is a strong source of the 4050 Å bands of the C₃ radical. As a preliminary to the study of the chemical kinetics involved in the formation of the electronically excited C₃ radical, a temperature investigation of the luminous mantle has been undertaken. Rotational measurements are reported for the CH, C₂, and OH bands over a range of burning mixtures of 2.3 to 4.2 times stoichiometric. Self-absorption is shown to occur for OH and C₂ and is indicated for CH. After attempting to correct for this effect, an average rotational temperature for the three radicals of 3000 ± 200° K. decreasing to 2900 ± 200° K. is found to be applicable to the luminous mantle over the range of mixtures investigated. Vibrational temperatures obtained for CN and C₂, together with predissociation studies of the CH radical, indicate that small departures from complete thermal equilibrium cannot be eliminated.