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标题：Energy levels and transition rates for helium-like ions with Z = 10–36
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作者：R. Si ; R. Si ; X. L. Guo 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2016
卷号：592
页码：1-10
DOI：10.1051/0004-6361/201628656
语种：English
出版社：EDP Sciences
摘要：Aims. Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10–36. Methods. The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results. We provide accurate energies for the lowest singly excited 70 levels among 1snl(n ≤ 6,l ≤ (n−1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln′l′(n′ ≤ 6,l′ ≤ (n′−1)) configurations of helium-like ions with Z = 10−36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions. Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics.
关键词：atomic data;atomic processes