Dielectronic recombination of argon-like ions

Nikolić, D.; Gorczyca, T. W.; Korista, K. T.; Badnell, N. R.

doi:10.1051/0004-6361/201014485

Cited by 29 publications

(29 citation statements)

References 62 publications

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“…RR dominates DR only at low temperatures (less than 1000-5000 K) for Se + , Se 3+ , and Se 6+ . This highlights the importance of obtaining accurate DR rate coefficients, as it is the principal recombination process for low-charge Se ions (and indeed for many other heavy elements, as noted for example by Badnell 2006a; Altun et al 2007;Nikolić et al 2010) in photoionized nebulae.…”

Section: Dielectronic Recombination Rate Coefficientsmentioning

confidence: 89%

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

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We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of distorted-wave photoionization (PI) cross sections, and total and partial final-state resolved radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six ions of the trans-iron element Se. These calculations were motivated by the recent detection of Se emission lines in a large number of planetary nebulae. Se is a potentially useful tracer of neutron-capture nucleosynthesis, but accurate determinations of its abundance in photoionized nebulae have been hindered by the lack of atomic data governing its ionization balance. Our calculations were carried out in intermediate coupling with semi-relativistic radial wavefunctions. PI and recombination data were determined for levels within the ground configuration of each ion, and experimental PI cross-section measurements were used to benchmark our results. For DR, we allowed Δn = 0 core excitations, which are important at photoionized plasma temperatures. We find that DR is the dominant recombination process for each of these Se ions at temperatures representative of photoionized nebulae (∼10 4 K). In order to estimate the uncertainties of these data, we compared results from three different configuration-interaction expansions for each ion, and also tested the sensitivity of the results to the radial scaling factors in the structure calculations. We find that the internal uncertainties are typically 30-50% for the direct PI cross sections and ∼10% for the computed RR rate coefficients, while those for low-temperature DR can be considerably larger (from 15-30% up to two orders of magnitude) due to the unknown energies of near-threshold autoionization resonances. These data are available at the CDS, and fitting coefficients to the total RR and DR rate coefficients are presented. The results are suitable for incorporation into photoionization codes used to numerically simulate astrophysical nebulae, and will enable robust determinations of nebular Se abundances.

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Section: Dielectronic Recombination Rate Coefficientsmentioning

confidence: 89%

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

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“…at http://amdpp.phys.strath.ac.uk/tamoc/DATA/ Colgan et al 2003Colgan et al , 2004Mitnik & Badnell 2004;Badnell 2006;Altun et al 2005Altun et al , 2006Altun et al , 2007Zatsarinny et al 2005aZatsarinny et al , 2005bZatsarinny et al , 2006Bautista & Badnell 2007;Nikolić et al 2010;Abdel-Naby et al 2012). For the Si to Mn isoelectronic sequences, the recombination rates are based on the works of Shull & van Steenberg (1982), Nahar (1996Nahar ( , 1997, Nahar & Bautista (2001), Mazzotta et al (1998), andMattioli (2002).…”

Section: Atomic Datamentioning

confidence: 99%

H TO Zn IONIZATION EQUILIBRIUM FOR THE NON-MAXWELLIAN ELECTRON κ-DISTRIBUTIONS: UPDATED CALCULATIONS

Dzifčáková

Dudík

2013

ApJS

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New data for the calculation of ionization and recombination rates have been published in the past few years, most of which are included in the CHIANTI database. We used these data to calculate collisional ionization and recombination rates for the non-Maxwellian κ-distributions with an enhanced number of particles in the high-energy tail, which have been detected in the solar transition region and the solar wind. Ionization equilibria for elements H to Zn are derived. The κ-distributions significantly influence both the ionization and recombination rates and widen the ion abundance peaks. In comparison with the Maxwellian distribution, the ion abundance peaks can also be shifted to lower or higher temperatures. The updated ionization equilibrium calculations result in large changes for several ions, notably Fe viii-Fe xiv. The results are supplied in electronic form compatible with the CHIANTI database.

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“…Table 1 shows a sample of results from selective models for the energy levels using the GRASP code for the lowest 16 levels of the residual Ca 2+ ion. The present results are compared with previous theoretical studies from the AUTOSTRUCTURE (AUTOS) [17,19] and MCHF codes [81] and with the NIST tabulated values [53]. From the results presented in table 1, it is clear that in order to achieve spectroscopic accuracy, much larger-scale configuration interaction models than considered here are required.…”

Section: Theorymentioning

confidence: 79%

Photoionisation of Ca⁺ions in the valence-energy region 20–56 eV: experiment and theory

Müller

Schippers

Phaneuf

et al. 2017

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Relative cross sections for the valence shell photoionisation (PI) of 2 S ground level and 2 D metastable Ca + ions were measured with high energy resolution by using the ion-photon merged-beams technique at the Advanced Light Source. Overview measurements were performed with a full width at half maximum bandpass of ∆E = 17 meV, covering the energy range 20 eV -56 eV. Details of the PI spectrum were investigated at energy resolutions reaching the level of ∆E = 3.3 meV. The photon energy scale was calibrated with an uncertainty of ±5 meV. By comparison with previous absolute measurements the present experimental high-resolution data were normalised to an absolute cross-section scale and the fraction of metastable Ca + ions that were present in the parent ion beam was determined to be 18±4%. Large-scale R-matrix calculations using the Dirac Coulomb approximation and employing 594 levels in the close-coupling expansion were performed for the Ca + (3s 2 3p 6 4s 2 S 1/2 ) and Ca + (3s 2 3p 6 3d 2 D 3/2,5/2 ) levels. The experimental data are compared with the results of these calculations and previous theoretical and experimental studies.

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Dielectronic recombination of argon-like ions

Cited by 29 publications

References 62 publications

Atomic data for neutron-capture elements

Atomic data for neutron-capture elements

H TO Zn IONIZATION EQUILIBRIUM FOR THE NON-MAXWELLIAN ELECTRON κ-DISTRIBUTIONS: UPDATED CALCULATIONS

Photoionisation of Ca⁺ions in the valence-energy region 20–56 eV: experiment and theory

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Dielectronic recombination of argon-like ions

Cited by 29 publications

References 62 publications

Atomic data for neutron-capture elements

Atomic data for neutron-capture elements

H TO Zn IONIZATION EQUILIBRIUM FOR THE NON-MAXWELLIAN ELECTRON κ-DISTRIBUTIONS: UPDATED CALCULATIONS

Photoionisation of Ca+ions in the valence-energy region 20–56 eV: experiment and theory

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Photoionisation of Ca⁺ions in the valence-energy region 20–56 eV: experiment and theory