Previous attempts at understanding the EUV N2 emissions have led to a considerable literature, filled with inconsistencies and uncertainties that have prevented reliable and quantitative analysis of upper-atmospheric emissions. Strong perturbative mixing of the c, c', e, e', and o Rydberg states and the b and b' valence states, as well as strong but unquantified predissociation by triplet states, means that we do not know the intensities of emission that would result from a supposed distribution of population among the vibrational levels of the electronic states. This inability to produce a trustworthy spectral simulation means that only limited information can be inferred from the spectra observed.
Under support from the Space Physics Division of the National Aeronautics and Space Administration (NASA), SRI is conducting a combined theoretical and experimental research program. The objectives of the theoretical component are to facilitate our ability to understand the N2 EUV emission spectrum by (1) developing a consistent model of N2 emissions in the 50 to 130 nm wavelength region, based on improved theoretical treatments and the best available experimental data and (2) developing a model of trapping and reemission of N2 c'-X radiation consistent with experimental findings on predissociation effects. The experimental part is concerned with increasing understanding of predissociation effects in the 13 to 14 eV states of N2.
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