Cross Section Measurements for Excitation and Ionization of Atmospheric Species

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This continuing project will conduct laboratory investigations of electron impact excitation and ionization cross sections for atmospheric species at Johns Hopkins University. Ionization and excitation are produced by both photoelectrons produced by the sun's extreme ultraviolet photon flux on atmospheric constituents and precipitated accelerated electrons in auroral zones. Excitation and ionization are also the main processes by which thermospheric electrons lose energy to the ambient atmosphere. Thus, we must gain familiarity with the cross sections for these electron impact processes to understand the rate of electron energy loss as well as intensities of optical emissions they produce. Specifically, we plan to measure ionization-excitation branching ratios for atomic oxygen ion production in all final electronic states of the ion. The work should significantly advance thermospheric modeling and many processes of interest in planetary atmospheres.