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

Abstract

A numerical two-dimensional spatial model is used to describe experimental results from the literature on the concentrations of O₂(a¹Δ_g) 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(a¹Δ_g) 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 k_rec(T) is obtained and agrees well with the available measured temperature dependences k_rec(T). Pathways for the subsequent relaxation of excited oxygen molecules and atoms are identified.