| 1. |
- Andersson, Martin, et al.
(författare)
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Analysis of the competition between forbidden and hyperfine-induced transitions in Ne-like ions
- 2016
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 93:3
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Tidskriftsartikel (refereegranskat)abstract
- In this work we investigate the decay of the |2p53sP03) state in neon-like ions along the isoelectronic sequence ranging from Z=10 to Z=35. In the absence of a nuclear spin, the magnetic dipole transition to |2p53sP13) is the dominating decay channel. However, for isotopes with a nuclear spin, the interaction between the nuclear magnetic dipole moment and the electronic field introduces a mixing of |2p53sP13) and |P11) into the |P03) state, which in turn opens up a competing hyperfine-induced electric dipole decay channel to the ground state. This hyperfine-induced transition channel clearly dominates over the magnetic dipole channel for the neutral end of the isoelectronic sequence, when present. We give values for the rates of both these competing channels and discuss how the introduction of the hyperfine-induced transition channel could have a dramatic influence on the spectrum, not only because it introduces a new line, but also since it can substantially decrease the intensity of the magnetic dipole 2p53sP03→2p53sP13 line and affect the predicted ionization balance in different plasmas.
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| 2. |
- Guo, Xueling, et al.
(författare)
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Energy levels and radiative data for Kr-like W38+ from MCDHF and RMBPT calculations
- 2016
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 49:13
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Tidskriftsartikel (refereegranskat)abstract
- Energies, transition rates, line strengths and lifetimes have been computed for all levels of the 4p 6 and 4p 54d configurations of W38+ by using the multi-configuration Dirac-Hartree-Fock (MCDHF) method as well as relativistic many-body perturbation theory. We investigate systematically correlation, relativistic and quantum electro-dynamical (QED) effects of different properties, including excitation energies and transition rates. We demonstrate that it is important to include the core-valence correlation of rather deep subshells (including 3d and 3p) to reach close to spectroscopic accuracy for the transition energies. We also show that high-multipole transitions (E3, M2) are important for the lifetime of some metastable levels of 4p 54d (). The present results are in good agreement with experiments and of considerably higher accuracy than those achieved in previous theoretical works.
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| 3. |
- Li, Wenxian, et al.
(författare)
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ATOMIC-LEVEL PSEUDO-DEGENERACY of ATOMIC LEVELS GIVING TRANSITIONS INDUCED by MAGNETIC FIELDS, of IMPORTANCE for DETERMINING the FIELD STRENGTHS in the SOLAR CORONA
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X. ; 826:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe9+ from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between 3p4 3d 4D7/2 the and 4D7/2 levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3p4 3d 4D7/2 → 3p5 2 P3/2 line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly dependent on the energy separation in the pseudo-degeneracy through the mixing induced by the external magnetic field. Our measurement, which uses an Electron Beam Ion Trap with a known magnetic-field strength, indicates that this energy difference is 3.5 cm-1. The high abundance of Fe9+ and the sensitivity of the line's transition probability to field strengths below 0.1 T opens up the possibility of diagnosing coronal magnetic fields. We propose a new method to measure the magnetic field in the solar corona, from similar intensity ratios in Fe9+. In addition, the proposed method to use the line ratio of the blended line 3p4 3d 4D7/2.5/2 → 3p5 2P3/2 with another line from Fe x as the density diagnostic should evaluate the effect of the magnetic-field-induced transition line.
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