Experimental photoionization cross-section measurements in the ground and metastable state threshold region of Se<sup>+</sup>

Sterling, N. C.; Esteves, D.; Bilodeau, R. C.; Kilcoyne, A. L. D.; Red, Eddie; Phaneuf, R. A.; Aguilar, A.

doi:10.1088/0953-4075/44/2/025701

Cited by 21 publications

(56 citation statements)

References 32 publications

(56 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the case of PI, we also compared our cross sections to recent experimental measurements (Esteves et al 2009(Esteves et al , 2010Sterling et al 2011) to gauge the accuracy of our results. We find that the direct PI cross sections for these Se ions are uncertain by 30-50%, while the RR rate coefficients are uncertain by <10% except for Se + (∼30-40%).…”

Section: Discussionmentioning

confidence: 90%

“…Se + , Se 2+ , Se 3+ , and Se 5+ cross sections 2 were measured from the threshold of the highest-energy metastable state in the ground configuration up to 10 eV beyond the ground state ionization threshold (Esteves et al 2010). Experimental results for Se + (Sterling et al 2011) and Se 3+ (Esteves et al 2009) have been published, and we compare our theoretical results to experiment for those ions in this section (a similar comparison to the as-yet unpublished Se 2+ and Se 5+ cross sections was also performed).…”

Section: Comparison To Experimentsmentioning

confidence: 81%

“…The experimental measurements were described by Esteves et al (2009) and Sterling et al (2011), and we refer the reader to those papers for full details. Briefly, the PI cross sections were measured via the merged beam method (Lyon et al 1986).…”

Section: Comparison To Experimentsmentioning

confidence: 99%

“…The photoionization spectra were measured by scanning across photon energies, and normalized to an absolute scale with absolute cross-section measurements performed at discrete energies. Overall, uncertainties in the experimental cross sections were estimated to be ∼30% for Se + and ∼20% for Se 3+ (Sterling et al 2011;Esteves et al 2009). …”

Section: Comparison To Experimentsmentioning

confidence: 99%

“…We therefore utilize recently conducted experimental PI cross-section measurements of Se ions (Esteves et al 2009;Sterling et al 2011;Esteves et al 2010;Esteves et al, in prep. ) as a comparison and benchmark to our calculations.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 90%

Section: Comparison To Experimentsmentioning

confidence: 81%

Section: Comparison To Experimentsmentioning

confidence: 99%

Section: Comparison To Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

View full text Add to dashboard Cite

show abstract

Advances in atomic data for neutron-capture elements

Sterling¹,

Witthoeft²,

Esteves³

et al. 2011

Proc. IAU

View full text Add to dashboard Cite

Abstract. Neutron(n)-capture elements (atomic number Z > 30), which can be produced in planetary nebula (PN) progenitor stars via s-process nucleosynthesis, have been detected in nearly 100 PNe. This demonstrates that nebular spectroscopy is a potentially powerful tool for studying the production and chemical evolution of trans-iron elements. However, significant challenges must be addressed before this goal can be achieved. One of the most substantial hurdles is the lack of atomic data for n-capture elements, particularly that needed to solve for their ionization equilibrium (and hence to convert ionic abundances to elemental abundances). To address this need, we have computed photoionization cross sections and radiative and dielectronic recombination rate coefficients for the first six ions of Se and Kr. The calculations were benchmarked against experimental photoionization cross section measurements. In addition, we computed charge transfer (CT) rate coefficients for ions of six n-capture elements. These efforts will enable the accurate determination of nebular Se and Kr abundances, allowing robust investigations of s-process enrichments in PNe.

show abstract

Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

Sterling

2016

Proc. IAU

View full text Add to dashboard Cite

Neutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more than 100 PNe in the Milky Way and nearby galaxies. In some objects, several different n-capture elements have been detected, providing valuable constraints to models of AGB nucleosynthesis and evolution. These detections have motivated theoretical and experimental investigations of the atomic data needed to derive accurate n-capture element abundances. In this review, I discuss the methods and results of these atomic data studies, and their application to abundance determinations in PNe.Comment: 8 pages, 2 figures. Invited review to appear in the Proceedings of IAU Symp. 323: "Planetary nebulae: Multi-wavelength probes of stellar and galactic evolution". Eds. X.-W. Liu, L. Stanghellini and A. Karaka

show abstract

Experimental photoionization cross-section measurements in the ground and metastable state threshold region of Se⁺

Cited by 21 publications

References 32 publications

Atomic data for neutron-capture elements

Atomic data for neutron-capture elements

Advances in atomic data for neutron-capture elements

Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

Contact Info

Product

Resources

About

Experimental photoionization cross-section measurements in the ground and metastable state threshold region of Se+

Cited by 21 publications

References 32 publications

Atomic data for neutron-capture elements

Atomic data for neutron-capture elements

Advances in atomic data for neutron-capture elements

Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

Contact Info

Product

Resources

About

Experimental photoionization cross-section measurements in the ground and metastable state threshold region of Se⁺