KINETICS OF NONEQUILIBRIUM EXCITATION OF CARBON MONOXIDE MOLECULESDURING HIGH-TEMPERATURE OXIDATION OF METHANE

Abstract

The time profiles of nonequilibrium radiation of electronically excited state of carbon monoxide CO (a3Πr) formed in the oxidation of methane behind shock waves at high temperatures were registered for the first time. The experiments were carried out in mixtures of CH4 with N2O and O2 in argon at temperatures of 2200—4200~K and pressures of 240±40~kPa. Intensive peaks of ultraviolet (UV) radiation from the Cameron bands of the CO molecules at a wavelength of 216 nm, sharply increasing with the temperature raise, were recorded. Simultaneously with the CO emission signals, absorption profiles of atomic oxygen at a~wavelength of 130.5~nm were recorded using atomic resonance absorption spectroscopy (ARAS) technique. To determine the quantitative concentration of the electronically excited state of CO, a series of calibration experiments was carried out in mixtures of~5\% and 10\% CO in argon at temperatures of 4000—5000~K. The analysis of the obtained data was carried out using a submechanism of formation and consumption of CO (a3Πr) during the oxidation of hydrocarbons, which was developed earlier and introduced into the existing modern complex kinetic mechanisms.