EUV Photoexcitation and Emission of N2 at Low Temperatures

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AST-0906158WuThis project will provide the necessary photo-excitation and emission data required to understand the important molecular physics and role in planetary atmospheres of molecular nitrogen (N2) by investigating the strong interactions among the Rydberg and valence states of N2 and the atmospheric N2, neutral atomic (NI) and ionized (NII) nitrogen emissions. Measurement of high-resolution fluorescence excitation spectra will determine the absolute predissociation yields when the experiments are conducted under optically thin conditions. The second part of this study will measure specific absolute branching ratios. The third significant activity will measure absolute fluorescence production cross-sections for the NI and NII emissions through photodissociative excitation and dissociative photoionization excitation of N2. The last task, similar work with isotopes of nitrogen, may be too ambitious for the scope of the current project, but would help to understand the nitrogen isotope anomaly observed in planetary atmospheres.The work will use an existing experimental apparatus that provides a rapid, efficient, and cost-effective means for observing fluorescence spectra and determining the absolute fluorescence production cross-sections. The experimental procedures have been developed by the PI's group, and will be conducted over a temperature range appropriate to the atmospheres of outer giant planets and satellites. These data are required for accurate quantitative analysis and evaluation of the nitrogen airglow models of Saturn, Titan, Triton, and Pluto.The results will benefit atomic and molecular theorists, atmospheric modelers, and optical astronomers. Several of the spectral features are of considerable interest as remote global sensing alternatives or as complementary measurements to existing bands. The study will continue successful efforts in training and research experiences for postdoctoral associates, graduate and undergraduate students.This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).