COMPUTATIONAL STUDIES OF ATMOSPHERIC CHEMISTRY SPECIES .16. A COMPUTATIONAL THERMODYNAMIC EVALUATION OF THE ALTITUDE PROFILES OF (N2)2, N2-O2 AND (O2)2 IN THE EARTHS ATMOSPHERE

The equilibrium constants of formation of the gas phase species (N2)2, N2-O2 and (O2)2 are used for evaluation of the altitude population pr ofiles in the Earth's atmosphere. The equilibrium constants are derive d from recently computed quantum-chemical data. Estimates of the lower bounds of the interaction energies are employed so that the reported data should also represent a lower bound of the populations. The mole fractions of each of the dimers, computed for their equilibrium mixtur e with N2 and O2 under atmospheric conditions, decrease with altitude. The mole fractions decrease in the order (N2)2, N2-O2, and (O2)2. The (N2)2 mole fraction close to the surface is found to be 8 X 10(-4)%, i.e. comparable with other minor components of the Earth's atmosphere currently being vigorously studied.