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

Abstract

The hyperfine constants of the levels 2p 2 ( 3 P)3s 4 PJ , 2p 2 ( 3 P)3p 4 P o J and 2p 2 ( 3 P)3p 4 D o J , deduced by Jennerich et al. [Eur. Phys. J. D 40, 81 (2006)] from the observed hyperfine structures of the transitions 2p 2 ( 3 P)3sby 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. PACS. PACS-key 31.15.aj,31.30.Gs,32.10.Fn -PACS-key 78.47.N In 1943, Holmes [3] measured the isotope shifts (IS) of the 2p 2 ( 3 P)3s 4 P J → 2p 2 ( 3 P)3p 4 P o J , 2p 2 ( 3 P)3s 2 P J → 2p 2 ( 3 P)3p 2 P o J and 2p 2 ( 3 P)3s 4 P J → 2p 2 ( 3 P)3p 4 S o J arXiv:1005.0953v2 [physics.atom-ph]

From atoms to biomolecules: a fruitful perspective

“…For hyperfine structures of 15 N and 14 N spectral lines observed in the near-infrared [85], we estimated ab initio hyperfine constants [91] that disagree completely with the experimental parameters obtained by fitting the observed hyperfine spectra [85]. We proposed a new interpretation of the recorded weak spectral lines [21] as crossover signals, producing a new set of experimental hyperfine constants in very good agreement with the ab initio predictions. This exemplifies the crucial role of theoretical atomic structure calculations in the interpretation of high resolution spectroscopy experiments.…”

“…For instance, the investigation of molecular dynamics is achieved by developing both wave packet propagation techniques [110] and molecular structure methodologies [112]. Another example is the continuous quest for new approaches to take electron correlation into account [174] that remains, since the beginning of ab initio calculations, the key for an adequate description of atomic [21] and molecular structures and properties [107]. A number of our research projects have direct astrophysical applications, including the determination of accurate atomic oscillator strengths and the investigation of isotopic and nuclear effects [71], the characterization of molecules suspected in space [137], the determination of rotational intensities to predict molecular abundances [29], or the calculation of rate constants for charge transfer processes [168,169].…”

From atoms to biomolecules: a fruitful perspective

“…For hyperfine structures of 15 N and 14 N spectral lines observed in the near-infrared [85], we estimated ab initio hyperfine constants [91] that disagree completely with the experimental parameters obtained by fitting the observed hyperfine spectra [85]. We proposed a new interpretation of the recorded weak spectral lines [21] as crossover signals, producing a new set of experimental hyperfine constants in very good agreement with the ab initio predictions. This exemplifies the crucial role of theoretical atomic structure calculations in the interpretation of high resolution spectroscopy experiments.…”

“…For instance, the investigation of molecular dynamics is achieved by developing both wave packet propagation techniques [110] and molecular structure methodologies [112]. Another example is the continuous quest for new approaches to take electron correlation into account [174] that remains, since the beginning of ab initio calculations, the key for an adequate description of atomic [21] and molecular structures and properties [107]. A number of our research projects have direct astrophysical applications, including the determination of accurate atomic oscillator strengths and the investigation of isotopic and nuclear effects [71], the characterization of molecules suspected in space [137], the determination of rotational intensities to predict molecular abundances [29], or the calculation of rate constants for charge transfer processes [168,169].…”

Relativistic effects on the hyperfine structures of2p4(3P)3p2Do,<

“…On the other hand, ab initio calculations of hyperfine constants for 14 N and 15 N [14] were found to be in complete disagreement with the experimental values of Jennerich et al [15], also deduced from the analysis of the near-infrared Doppler-free saturated absorption spectra. This nitrogen theory-observation discrepancy problem was recently solved through a reinterpretation of the recorded weak spectral lines as crossover signals [16], leading to a new set of experimental hyperfine constants in very good agreement with the ab initio predictions [14]. Considering that the apparition of crossover signals in Doppler-free saturated absorption spectroscopy that has been used for both fluorine [3] and nitrogen [15], is helpful in some cases but also problematic in others, we investigate in the present work the relativistic corrections that could explain the non relativistic theory-observation discrepancy mentioned above for the A 5/2 -value of 2p…”