Generation of Oxygen Atoms during Laser Photolysis of O2 behind Reflected Shock Waves and the Kinetics of Their Interaction with Methane

In this paper, the first experimental results of measuring the time profiles of the atomic oxygen concentration by atomic resonance absorption spectroscopy (ARAS, 130.5 nm) obtained using the developed experimental complex combining shock-wave heating and pulsed laser photolysis (LP, 193 nm) of gas mixtures are presented. Using the example of photolysis of oxygen molecules and the reaction of O atoms with methane, the capabilities of the developed setup for studying the kinetics of elementary reactions are demonstrated. The temperature dependence of the absorption cross section of oxygen and methane molecules for a wavelength of 130.5 nm is obtained. The efficiency of oxygen atom formation during the laser photolysis of oxygen molecules is determined in the temperature range of 700–1900 K at laser pulse energies of 300–400 mJ. The rate constant of the reaction of oxygen atoms with methane at temperatures of 770–1600 K and pressures of 3–4 bar is obtained. Additionally, numerical modeling of experimental profiles is carried out using current kinetic schemes of hydrocarbon combustion.