Saturation spectra of low lying states of Nitrogen: reconciling experiment with theory

The hyperfine constants of the levels 2 p 2 P)3 s 4 P J , 2 p 2 P)3 p 4 P and 2 p 2 P)3 p 4 D , deduced by Jennerich et al. [Eur. Phys. J. D 40 , 81 (2006)] from the observed hyperfine structures of the transitions 2 p 2 P)3 s 4 P J 2 p 2 P)3 p 4 P and 2 p 2 P)3 s 4 P J 2 p 2 P)3 p 4 D recorded by saturation spectroscopy in the near-infrared, strongly disagree with the ab initio values of Jönsson et al. [J. Phys. B: At. Mol. Opt. Phys. 43 , 115006 (2010)]. We propose a new interpretation of the recorded weak spectral lines. If the latter are indeed reinterpreted as crossover signals, a new set of experimental hyperfine constants is deduced, in very good agreement with the ab initio predictions.