Dirac R-matrix calculation for electron-impact excitation of S xiii
Dirac R-matrix calculation for electron-impact excitation of S xiii
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DOI：
10.1051/0004-6361/201321816
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发表时间：
2013-08
影响因子：
6.5
通讯作者：
Fei Li;G. Liang;M. A. Bari;Gang Zhao
中科院分区：
文献类型：
--
作者：
Fei Li;G. Liang;M. A. Bari;Gang Zhao
语境。在各种实验室和天体物理光谱中都可以观察到软 X 射线和极紫外区域的硫发射线。但最先进的 NLTE 光谱模型的 S xiii 的准确电子碰撞激发数据很少。目标。我们计算了对应于主量子数 n = 2,3,4 的最低 98 个精细结构态 1s 2 2lnl 之间跃迁的电子碰撞激发碰撞强度和 S xiii 的有效碰撞强度。在各种天体物理等离子体条件下，在较宽的温度范围（log10 Te (K) = 4.53-7.53）内计算了这些转变的有效碰撞强度。方法。我们使用完全相对论并行狄拉克 R 矩阵代码来计算碰撞强度。为了生成用于散射计算的目标波函数和能级，我们采用了 GRASP0 多配置 Dirac-Fock 代码，状态高达 n = 5。 结果。波函数由 27 种配置生成 - 1s 2 2lnl � (n = 2,3,4,5) - 产生 166 个 jj 能级。将最低98个精细结构级别之间的碰撞和有效碰撞强度与之前的理论计算进行了比较。大多数跃迁的碰撞强度在较高的入射电子能量下非常一致。结论。在较低温度下，共振对有效碰撞强度的贡献最为显着。
Context. Sulfur emission lines in the soft X-ray and extreme-ultraviolet regions are observed in a variety of laboratory and astrophys- ical spectra. But accurate electron impact excitation data for S xiii for state-of-the-art NLTE spectral models are scarce. Aims. We calculated electron-impact excitation collision strengths and effective collision strengths of S xiii for transitions among the lowest-lying 98 fine-structure states 1s 2 2lnlcorresponding to principal quantum numbers n = 2,3,4. The effective collision strengths for these transitions were computed over a wide temperature range (log10 Te (K) = 4.53-7.53) for various astrophysical plasma conditions. Methods. We used the fully-relativistic parallel Dirac R-matrix code to calculate collision strengths. To generate target wavefunctions and energy levels for scattering calculations, we employed the GRASP0 multi-configuration Dirac-Fock code for states up to n = 5. Results. The wavefunctions are generated from 27 configurations - 1s 2 2lnl � (n = 2,3,4,5) - giving rise to 166 jjenergy levels. The collision and effective collision strengths among the lowest 98 fine-structure levels are compared with the previous theoretical calculations. The collision strengths for most transitions agree well at higher incident electron energies. Conclusions. The resonant contributions to effective collision strengths are most dominant at lower temperatures.