Abstract. Hyperfine structure parameters are calculated for the 2p 2 ( 3 P )3s 4 P J , 2p 2 ( 3 P )3p 4 P o J and 2p 2 ( 3 P )3p 4 D o J levels, using the ab initio multiconfiguration Hartree-Fock method. The theoretical hyperfine coupling constants are in complete disagreement with the experimental values of Jennerich et al. [1] deduced from the analysis of the near-infrared Doppler-free saturated absorption spectra.

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]

The hyperfine structures of 7,9Be−  2s2p2  4P 1/2,3/2,5/2 are investigated theoretically using the multiconfiguration Hartree–Fock and configuration interaction methods. The effects of the hyperfine mixing between the fine-structure J-levels are discussed. The feasibility of some atomic spectroscopy experiments, allowing determination of the 7Be quadrupole moment from the observed hyperfine structure of the 7Be− negative ion and from the present electronic parameters, is investigated. The Be 2s2p 3Po electron affinity is monitored as a function of the orbital and configuration spaces to assess the reliability of the wavefunctions of the neutral atom and the negative ion. The theoretical value nicely converges towards the most recent theoretical and experimental results.

The relativistic corrections to the magnetic dipole moment operator in the Pauli approximation were derived originally by Drake [1]. In the present paper, we derive their irreducible tensor-operator form to be used in atomic structure codes adopting the Fano-Racah-Wigner algebra for calculating its matrix elements.