Accurate Fourier-transform spectroscopic absorption measurements of vacuum ultraviolet transitions in atomic nitrogen and carbon were performed at the Soleil synchrotron. For 14N, transitions from the 2s22p3 4S3/2 ground state and from the 2s22p3 2P and 2D metastable states were determined in the 95-124 nm range at an accuracy of 0.025 cm-1. The combination of these results with data from previous precision laser experiments in the vacuum ultraviolet range reveals an overall and consistent offset of -0.04 cm-1 from values reported in the NIST database. The splittings of the 2s22p3 4S3/2 - 2s2p4 4PJ transitions are well-resolved for 14N and 15N and the isotope shifts determined. While excitation of a 2p valence electron yields very small isotope shifts, excitation of a 2s core electron results in large isotope shifts, in agreement with theoretical predictions. For carbon, six transitions from the ground 2s22p2 3PJ and 2s22p3s 3PJ excited states at 165 nm are measured for both 12C and 13C isotopes.
Bibliographical noteArticle belongs to the Section: Atomic, Molecular and Nuclear Spectroscopy and Collisions.
- Isotope shift
- Vacuum ultraviolet