Precise determination of the 2s22p5-2s2p6 transition energy in fluorine-like nickel utilizing a low-lying dielectronic resonance

Abstract

High precision spectroscopy of the low-lying dielectronic resonances in fluorine-like Ni 19+ ions was studied by employing the electron-ion merged-beams method at the heavy-ion storage ring CSRm. The measured dielectronic-recombination (DR) resonances are identified by comparison with relativistic calculations utilizing the flexible atomic code (FAC). The lowest-energy resonance at about 86 meV is due to DR via (2s2p 6 [ 2 S 1/2 ]6s)J=1 intermediate state. The position of this resonance could be determined within an experimental uncertainty of as low as ±4 meV. The binding energy of the 6s Rydberg electron in the resonance state was calculated using two different approaches, the Multi-Configurational Dirac-Hartree-Fock (MCDHF) method and the Stabilization Method (SM). The sum of the experimental (2s2p 6 [ 2 S 1/2 ]6s)J=1 resonance energy and the theoretical 6s binding energies from the MCDHF and SM calculations, yields the following values for the 2s 2 2p 5 2 P 3/2 → 2s2p 6 2 S 1/2 transition energy149.056(4)exp(20) theo and 149.032(4)exp(6) theo , respectively. The theoretical calculations reveal that second-order QED and third-order correlation effects contribute by together about 0.1 eV to the total transition energy and can, thus, be assessed by the present precision DR spectroscopic measurement.

Atomic structure and collision dynamics with highly charged ions

“…[44,45] Moreover, the 2s 2 2p 5 [ 2 P 1/2 ] → 2s2p 6 [ 2 S 1/2 ] core transition energy in the Flike Ni 19+ ions has been precisely determined and the second order QED effects are tested, which benefits from the accurate measurement of the low-lying dielectronic resonances associated with the (2s2p 6 [ 2 S 1/2 ]6s)J = 1 intermediate state and the precise calculations of the binding energy of the 6s Rydberg electrons. [46] In addition, strong mixing effects between the low lying ∆n = 0 and ∆n = 1 DR resonances have been revealed in the investigation of DR spectroscopy for the Na-like Kr 25+ ions. [41] In the past few years, a series of DR experiments for different HCIs have been investigated at the CSR, such as Ar 12+,13+,14+,15+ , Ca 14+,16+,17+ , Ni 19+ , and Kr 25+ ions, electron correlations are studied.…”