scholarly journals Effective collision strengths for electron-impact excitation of Al10+

2006 ◽  
Vol 24 (2) ◽  
pp. 235-240 ◽  
Author(s):  
V. STANCALIE ◽  
V. PAIS
Keyword(s):  
Electron Impact ◽  
Maximum Energy ◽  
Impact Excitation ◽  
Electron Collision ◽  
Electron Impact Excitation ◽  
Coupling Scheme ◽  
Close Coupling ◽  
R Matrix ◽  
Intermediate Coupling Scheme ◽  
Effective Collision

Electron collision strengths for electron-impact excitation of Li-like and Al ion are evaluated in close-coupling approximation using the multi-channel R-matrix method. Five LS target eigenstates are included in the expansion of the total wave function, consisting of the twon= 2 states withconfigurationsof 1s22s, 1s22p, and threen= 3 states withconfigurations1s23s, 1s23p, and 1s23d. Collision strengths are obtained in LS coupling using FARM code and in intermediate coupling scheme using the SUPERSTRUCTURE program. The effective collision strengths are calculated as function of temperature, up to a temperature that does not exceed half of the maximum energy in the R-matrix run.

scholarly journals R-matrix electron-impact excitation data for the C-like iso-electronic sequence

2020 ◽  
Vol 634 ◽  
pp. A7 ◽  
Author(s):  
J. Mao ◽  
N. R. Badnell ◽  
G. Del Zanna
Keyword(s):  
Electron Impact ◽  
Energy Levels ◽  
Transformation Method ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Astrophysical Plasmas ◽  
Close Coupling ◽  
The Impact ◽  
Effective Collision

Context. Emission and absorption features from C-like ions serve as temperature and density diagnostics of astrophysical plasmas. R-matrix electron-impact excitation data sets for C-like ions in the literature merely cover a few ions, and often only for the ground configuration. Aims. Our goal is to obtain level-resolved effective collision strength over a wide temperature range for C-like ions from N II to Kr XXXI (i.e., N+ to Kr30+) with a systematic set of R-matrix calculations. We also aim to assess their accuracy. Methods. For each ion, we included a total of 590 fine-structure levels in both the configuration interaction target and close-coupling collision expansion. These levels arise from 24 configurations 2l3nl′ with n = 2−4, l = 0−1, and l′ = 0−3 plus the three configurations 2s22p5l with l = 0−2. The AUTOSTRUCTURE code was used to calculate the target structure. Additionally, the R-matrix intermediate coupling frame transformation method was used to calculate the collision strengths. Results. We compare the present results of selected ions with archival databases and results in the literature. The comparison covers energy levels, transition rates, and effective collision strengths. We illustrate the impact of using the present results on an Ar XIII density diagnostic for the solar corona. The electron-impact excitation data is archived according to the Atomic Data and Analysis Structure (ADAS) data class adf04 and will be available in OPEN-ADAS. The data will be incorporated into spectral codes, such as CHIANTI and SPEX, for plasma diagnostics.

Relativistic R-matrix close-coupling method based on the effective many-body Hamiltonian: electron-impact excitation of the 3s2 1S0–3s3p1P1o electric dipole-allowed transition of the Ar6+ ion1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

2011 ◽  
Vol 89 (4) ◽  
pp. 457-463
Author(s):  
Juan A. Santana ◽  
Yasuyuki Ishikawa
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Electric Dipole ◽  
Coupling Method ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Many Body ◽  
Close Coupling ◽  
R Matrix ◽  
Excitation Cross Sections

Electron-impact excitation cross sections of the electric dipole-allowed 3s2 1S0–3s3p [Formula: see text] transition in Mg-like argon (Ar6+) are calculated using the configuration-interaction and effective many-body Hamiltonian R-matrix close-coupling methods. The near-threshold electron-impact excitation cross sections computed with the effective many-body Hamiltonian R-matrix close-coupling method are in good agreement with the benchmark experimental results.

scholarly journals Electron Impact Excitation of S III: An Assessment

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 78
Author(s):  
Kanti M. Aggarwal
Keyword(s):  
Electron Impact ◽  
Energy Levels ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
R Matrix ◽  
B Spline ◽  
Hartree Fock ◽  
Effective Collision

In a recent paper, Tayal et al. (Astrophys. J. Suppl. 2019, 242, 9) reported results for energy levels, radiative rates (A-values), and effective collision strengths ( Υ ) for transitions among the 198 levels of Si-like S III. For the calculations, they adopted the multi-configuration Hartree–Fock (MCHF) code for the energy levels and A-values and the B-spline R-matrix (BSR) code for Υ . Their reported results appear to be accurate for energy levels and A-values, but not for Υ . Through our independent calculations by adopting the flexible atomic code (FAC), we demonstrate that their reported results for Υ are underestimated, by up to a factor of two, and at all temperatures, particularly for the allowed transitions, but some forbidden ones as well. Additionally, for transitions involving the higher levels, the behaviour of their Υ results is not correct.

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