Spectral Study of Flames of Carbon Vapor at Low Pressure

Abstract

Gas-phase reactions of carbon vapor near room temperature with simple gases and their discharge products have been spectrally observed for the first time. Experimental arrangements for obtaining carbon vapor and mixing it with discharge products or gases in a low-pressure flow system are presented. Spectra of the carbon vapor flames with oxygen, atomic oxygen, and atomic nitrogen have been obtained over the range 2200 to 7000 Å. Molecular-oxygen flames emit the C2 Swan and CO triplet and third positive bands. Flames with atomic oxygen are much more intense than flames with molecular oxygen and emit the C3 4050 Å group in addition to C2 and CO bands. Bands from ν=2 in the C2 Swan system are found to be enhanced in atomic- and molecular-oxygen flames. On addition of molecular or atomic hydrogen to the atomic-oxygen flame, CH 4315- and 3900- Å and OH 3064- Å bands appear. Atomic-nitrogen flames emit the CN red and violet systems with considerable intensity in bands from high vibrational levels. Spectra of these flames have been studied as a function of pressure, flow rates, carrier gas, and methods of obtaining carbon vapor. Mechanisms for formation and excitation of the emitters of the various bands are suggested.