Isotope shifts in Sb I

MCDHF calculations of isotope shifts in neutral antimony

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a b s t r a c tAb initio multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations have been carried out in order to determine the isotope shift (IS) electronic parameters of transitions belonging to electric dipole (E1) transition arrays 5s 2 5p 3 − 5s 2 5p 2 6s , 5s 2 5p 2 6s − 5s 2 5p 2 6p and 5s 2 5p 2 6s − 5s 2 5p 2 7p in neutral antimony, Sb I. In a correlation model limited to single and double excitations from the valence shells, these parameters, combined with the changes in mean-square nuclear charge radius δ r 2 123,121 compiled by Angeli and Marinova [3] produce isotope shifts values in good agreement with the most recent measurements by high-resolution emission and optogalvanic absorption spectroscopy of Sobolewski et al [5] but not with the old measurements of Buchholz et al [4] for 5p 3 − 5p 2 6s . However, our analysis does not allow to reject the latter due to the large uncertainty affecting δ r 2 123,121 , i.e.

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“…where ˜ K ul = ˜ K u −˜ K l refers to the mass-shift electronic parameter, F ul = F u − F l is the field-shift electronic factor and δ r 2 M,M ≡ r 2 M − r 2 M is the mean-square nuclear charge radius difference between the two isotopes. The relativistic mass-shift electronic parameter ˜ K RMS for a level is related to the expectation value of the relativistic recoil Hamiltonian, H RMS , 5) or, in energy units,…”

“…Moreover, as far as the authors know, there are only two measurements of IS available in the literature [4,5] . They both concern exclusively the stable 121, 123 Sb isotopes.…”

“…0.072 ± 0.048 fm 2 . More recently, Sobolewski et al [5] extended the available experimental IS data in neutral antimony by measuring eight lines belonging to the E1 transition arrays 5s 2 5p 3 − 5s 2 5p 2 6s , 5s 2 5p 2 6s − 5s 2 5p 2 6p and 5s 2 5p 2 6s − 5s 2 5p 2 7p . Large discrepancies have been found between the two sets of experimental IS for the three common lines at λ = 363 .…”

“…The agreement between their experimental IS and their calculated IS was found to be rather satisfactory, except for the transition 5s 2 5p 2 6s 4 P 3 / 2 − 5s 2 5p 2 6p (1 , 3 / 2) o 5 / 2 at 1074.2 nm where a discrepancy factor ∼ 2 was observed. In Sobolewski et al [5] , two different approaches were used. On one hand, the Vinti integrals involved in the SMS contribution were computed using the pseudo-relativistic Hartree-Fock (HFR) method of Cowan [7] without distinguishing radially the p 1/2 and p 3/2 electrons.…”