High-Resolution Absorption Spectra of Nitrogen in the Vacuum Ultraviolet.

The absorption spectrum of the LBH (Lyman-Birge-Hopfield) system (a1110 - X' +g) of nitrogen has been obtained for the first time under high resolution. The 0-0,1-0, and 2-0 bands have been analyzed, and the results on the ground state show excellent agreement with high-resolution Raman data. A critical analysis (and recomputation) of recent emission data on the LBH and b'-X bands shows substantial agreement with the present investigation and produces small changes in the molecular constants (Be = 1.6155 , a, = 0.01780 cm ' for a illg; B, = 1.9987, a, 0.01781 for X' g+). The experimental methods used in the present work and the treatment of the data are discussed, with special attention to a comparison of the experimental accuracies with the emission and the Raman data.