On how atmospheric temperature affects the intensity of oxygen emissions in the framework of the Barth’s mechanism

Abstract

The three-body recombination of oxygen atoms O + O + M → O2(el) + M is the dominant process of oxygen excitation in the Earth’s nightglow at altitudes of 85–110 km. The rate coefficient of this reaction, as well as the quantum yields of electronically excited products (O2(el) in the electronic states: 5πg, A3Σu+, A′3Δu, c1Σu+, b1Σg+, a1Δg, X3Σg-) depend on the gas kinetic temperature. In addition to the direct one-stage excitation channel of these levels of the O2 molecule, the Barth’s mechanism considers the two-stage energy transfer channel. In this channel, higher excited levels of the O2 act as precursors for the excitation of the O(1S) atom and the underlying electronic levels of the O2. In this study, we use sensitivity analysis to consider the temperature dependence of the processes of excitation and quenching for each of the excited components. The analytical expressions are obtained for the sensitivity coefficients of the Volume Emission Rates depending on temperature for the green line of atomic oxygen O(1S → 1D), the Herzberg I band O2(A3Σu+→X3Σg-) and O2 Atmospheric band O2(b1Σg+,v'=0→X3Σg-, v''=0). With the help of the sensitivity analysis performed in this work, we (a) confirm that the state O2(5πg), produced by the three-body recombination of atomic oxygen, is a precursor for the formation of O2(b1Σg+), (b) estimate the quantum yield of the O2(b1Σg+) state formed as a result of collisional reaction O2(5πg) with O2, and (c) propose a method for determining a type of precursor for production of O(1S) in the Barth's mechanism.