Basic Ionization, Airglow and Auroral Processes

Harvard University, Cambridge MA

Investigators

Abstract

ATM-9988461 Dalgarno The role of hot oxygen atoms on the chemistry, composition and the thermal structure of the atmosphere will be studied. Doppler profiles of emissions from electronically excited O(1D) atoms will be calculated. They are extensively used to determine thermospheric temperatures and neutral wind velocities. A major source of energetic oxygen atoms in ground (3P) and excited (1D) states is phototodissociation of O2 by solar ultraviolet radiation. Theoretical procedures will be applied to the quantitative determination of the cross sections, branching ratio and energy distributions of O (3P) and O (1D) atoms in the photodissociation of O2. Hot oxygen atoms are an important heating source of the neutral thermosphere. Their rate of thermalization strongly influences the heat and energy balance of the thermosphere. Semiclassical and quantum mechanical scattering calculations will be performed to evaluate the cross sections for collisions with both gases which thermalize the hot O atoms. By inserting the cross sections in the solutions of the Boltzmann equation, the non-equilibrium energy distribution functions of these atoms will be determined.