Mechanisms of the Production and Destruction of Singlet Oxygen and Ozone in Fast-Flowing O/O2/N2 Gas Mixtures

A numerical two-dimensional spatial model is used to describe experimental results from the literature on the concentrations of O2(a1Δg) and O2(b1 $$\Sigma _{{\text{g}}}^{ + }$$ ) in a fast-flowing gas system free of plasma–chemical processes with the participation of electrons and ions. The concentration profiles of O2(a1Δg) and O2(b1 $$\Sigma _{{\text{g}}}^{ + }$$ ) are found to depend on gas pressure, the fraction of oxygen atoms in O/N2 mixtures, and additions of O2 to the gas mixture. The model emphasizes the need to consider detailed vibrational kinetics of ozone and its formation on the surfaces of tube walls. A new interpretation is proposed for the three-body recombination of oxygen atoms on M = N2, O2, allowing for the reverse dissociation of the produced highly excited molecules. The resulting functional dependence of recombination rate coefficient krec(T) is obtained and agrees well with the available measured temperature dependences krec(T). Pathways for the subsequent relaxation of excited oxygen molecules and atoms are identified.