scholarly journals Dielectronic recombination rate coefficients of fluorine-like nickel

2019 ◽  
Vol 627 ◽  
pp. A171 ◽  
Author(s):  
Shu-Xing Wang ◽  
Zhong-Kui Huang ◽  
Wei-Qiang Wen ◽  
Chong-Yang Chen ◽  
Stefan Schippers ◽  
...  

Electron-ion recombination rate coefficients for fluorine-like nickel ions have been measured by employing the merged-beam technique at the cooler storage ring CSRm at the Institute of Modern Physics in Lanzhou, China. The measured spectrum covers the energy range of 0–160 eV, including all the dielectronic recombination (DR) resonances associated with ΔN = 0 core excitations. The DR cross sections in this energy range were calculated by a relativistic configuration interaction method using the flexible atomic code (FAC). Radiative recombination (RR) cross sections were obtained from a modified version of the semi-classical Bethe & Salpeter (1957, Quantum Mechanics of One- and Two-Electron 56 Systems (Springer)) formula for hydrogenic ions. The comparison between the measurement and the calculation shows that the present theoretical model still needs to be improved at low collision energies. Temperature dependent plasma recombination rate coefficients were derived from the measured DR rate coefficients in the temperature range of 103–108 K and compared with the presently calculated result as well as previous available data in the literature. The experimentally derived data agree well with the theoretical calculations for temperatures where Ni19+ ions form in collisionally ionized plasmas. At lower temperatures typical for photo-ionized plasmas, discrepancies are found beyond the experimental uncertainty, which can be attributed to the disagreement between the measurement and the calculation of the low-lying DR resonances. The present experimental result benchmarks the plasma DR rate coefficients, in particular for temperatures below 105 K where the ΔN = 0 DR resonances dominate.

2003 ◽  
Vol 58 (5-6) ◽  
pp. 346-350
Author(s):  
H. Ramadan ◽  
A. Khazbak ◽  
Ali H. Moussa

Dielectronic recombination (DR) cross sections and rate coefficients are calculated for the isonuclear sequence FeZ+, with Z = 21, 20, 19, 18, 17, and 16, in which L-shell (2p-) excitations are involved during the initial capture. Most of the dominant transitions with Δn ≠ 0, using angular momentum average (AMA) approximation, are considered. It is found that the states 3pnd and 3dnd contribute most to the rate coefficients. In addition, the rates are found to increase with increasing number of electrons in the ion, (i. e. as Z decreases). Moreover, the rate coefficients, αDR, for the studied ions are found to peak around the same energy (kT = 30 Ry). A semi-empirical formula for the total rates α is obtained for the 2p-excitation with Δn ≠ 0 in the case of FeZ+ ions. On comparing both results, the explicit calculations and the results obtained from the semiempirical formula, good agreement is found. The available results for αDR may be considered as a database for future comparison with experimental and theoretical calculations. Comparison of our results with other results show the effect of the empirical rate formula.


2009 ◽  
Vol 42 (10) ◽  
pp. 105203 ◽  
Author(s):  
Fan-Chang Meng ◽  
Li Zhou ◽  
Min Huang ◽  
Chong-Yang Chen ◽  
Yan-Sen Wang ◽  
...  

2005 ◽  
Vol 437 (3) ◽  
pp. 1151-1157 ◽  
Author(s):  
S. Böhm ◽  
A. Müller ◽  
S. Schippers ◽  
W. Shi ◽  
M. Fogle ◽  
...  

1996 ◽  
Vol 54 (4) ◽  
pp. 3070-3077 ◽  
Author(s):  
E. Behar ◽  
P. Mandelbaum ◽  
J. L. Schwob ◽  
A. Bar-Shalom ◽  
J. Oreg ◽  
...  

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