CHEMICAL REACTIONS IN ELECTRICAL DISCHARGES: I. THE SPECTRUM OF THE METHANE–OXYGEN SYSTEM AT LOW PRESSURE IN THE POSITIVE COLUMN OF A D-C. GLOW DISCHARGE

A technique is described which permits the study of changes in the spectra emitted by fast flowing reacting gas mixtures in the plasma of the positive column of a weak d-c. glow discharge. In certain cases a quantitative relationship is shown to exist between the concentration of a species and the intensity of emission of its spectrum. In particular such a correlation exists between the emission intensity of CO and its concentration. Use of this fact is then made to follow the rate of formation of carbon monoxide in methane–oxygen mixtures flowing through a discharge. The mechanism of formation of the various emitters either by means of a chemical reaction or by electron impact on molecules or radicals is discussed. It is concluded that to account for the rate of formation of CO, at least in the early stages of the presence of the gases in the discharge, before the steady state concentrations of atoms, radicals, and molecules have been approached, most of the energy of the electrons is used in breaking chemical bonds. The electric Held values needed to impart the necessary amount of energy to the electrons are of the same magnitude as those measured in this laboratory (~60 V cm−1).