Fourier-transform VUV spectroscopy of $^{14,15}$N and $^{12,13}$C

Abstract

Accurate Fourier-transform spectroscopic absorption measurements of vacuum ultraviolet transitions in atomic nitrogen and carbon were performed at the Soleil synchrotron. For 14 N transitions from the 2s 2 2p 3 4 S 3/2 ground state and from the 2s 2 2p 3 2 P and 2 D metastable states were determined in the 95 − 124 nm range at an accuracy of 0.025 cm −1 . Combination of these results with data from previous precision laser experiments in the vacuum ultraviolet range reveal an overall and consistent offset of -0.04 cm −1 from values reported in the NIST database. The splittings of the 2s 2 2p 3 4 S 3/2 -2s2p 4 4 PJ transitions are well-resolved for 14 N and 15 N and 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 2s 2 2p 2 3 PJ and 2s 2 2p3s 3 PJ excited states at 165 nm are measured for both 12 C and 13 C isotopes.