Measurements of the absolute photoionization cross section of Fe<sup> </sup>ions from 15.8 to 180 eV

Kjeldsen, H.; Kristensen, Benedikte Møller; Folkmann, F.; Andersen, T.

doi:10.1088/0953-4075/35/17/303

Cited by 36 publications

(60 citation statements)

References 36 publications

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“…The same problem has been observed in several other cases (see e.g. Kjeldsen et al 2002b), and for comparison Schippers et al (2003) used an energy grid of 13.6 × 10 −6 eV in their R-matrix calculation for the isoelectronic B + ion and observed excellent agreement with their experimental data. The more recent relativistic R-matrix results presented by Nahar (2004) slightly improve the description of the 1s 2 2pnp resonances in the case of O 4+ but also exhibit strange variations between the intensity of the peaks.…”

Section: +supporting

confidence: 70%

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

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Section: +supporting

confidence: 70%

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

Bizau

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Cubaynes

et al. 2005

A&A

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“…The photoionization cross section of Fe + was constructed using both the calculated values of Nahar & Pradhan (1994) and the experimental ones of Kjeldsen et al (2002b), following the prescriptions given by the latter authors. Other recent upgrades to the code are described by Simpson et al (2004).…”

Section: Model Resultsmentioning

confidence: 99%

The [Feiv] Discrepancy: Constraining the Iron Abundances in Nebulae

Rodríguez

Rubin

2005

ApJ

115

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We study the current discrepancy between the model-predicted and measured concentrations of Fe ++ and Fe +3 in ionized nebulae. We calculate a set of photoionization models, updated with the atomic data relevant to the problem, and compare their results with those derived for the available nebulae where both [Fe iii] and [Fe iv] lines have been measured. Our new model results are closer to the measured values than the results of previous calculations, but a discrepancy remains. This discrepancy translates into an uncertainty in the derived Fe abundances of a factor of up to $4. We explore the possible causes of this discrepancy and find that errors in the Fe atomic data may be the most likely explanation. The discrepancy can be fully accounted for by any of the following changes: (1) an increase by a factor of $10 in the recombination rate (radiative plus dielectronic, or charge transfer) for Fe +3 , (2) an increase by a factor of 2-3 in the effective collision strengths for Fe ++ , or (3) a decrease by a factor of 2-3 in the effective collision strengths for Fe +3 . We derive the Fe abundances implied by these three explanations and use the results to constrain the degree of depletion of Fe in our sample nebulae. The Galactic H ii regions and planetary nebulae are found to have high depletion factors, with less than 5% of their Fe atoms in the gas phase. The extragalactic H ii regions (LMC 30 Doradus, SMC N88A, and SBS 0335À052) have somewhat lower depletions. The metal-deficient blue compact galaxy SBS 0335À052 could have from 13% to 40% of Fe in the gas phase. The depletions derived for the different objects define a trend of increasing depletion at higher metallicities.

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“…On the experimental side, photoionization measurements for iron ions were made using synchrotron radiation and an atomic-beam technique. The absolute singleand double-photoionization cross sections of singly charged Fe ions have been measured from 15.8 to 180 eV using the merged-beam technique [3]. Experimental and theoretical studies of the photoionization cross section of Fe4+ ion between 59 and 140 eV photon energy were reported by Bizau et al [4], The available R-matrix calculations describe qualitatively well the results of the experiment in the 3p -*■ 3d excitation region.…”

Section: Introductionmentioning

confidence: 83%

Photoionization ofFe7+from the ground and metastable states

Tayal

Zatsarinny

2015

Phys. Rev. A

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The B-spline Breit-Pauli R-matrix method is used to investigate the photoionization of Fe7+ from the ground and metastable states in the energy region from ionization thresholds to 172 eV. The present calculations were designed to resolve the large discrepancies between recent measurements and available theoretical results. The multiconfiguration Hartree-Fock method in connection with B-spline expansions is employed for an accurate representation of the initial-and final-state wave functions. The close-coupling expansion includes 99 finestructure levels of the residual Fe8+ ion in the energy region up to 3s23p54s states. It includes levels of the 3s23p6, 3s23p53d, 3s23p54s, and 3s3p63d configurations and some levels of the 3s23p43d2 configuration which lie in the energy region under investigation. The present photoionization cross sections in the length and velocity formulations exhibit excellent agreement. The present photoionization cross sections agree well with the Breit-Pauli R-matrix calculation by Sossah et al. and the TOPbase data in the magnitude of the background nonresonant cross sections but show somewhat richer resonance structures, which qualitatively agree with the measurements. The calculated cross sections, however, are several times lower than the measured cross sections, depending upon the photon energy. The cross sections for photoionization of metastable states were found to have approximately the same magnitude as the cross sections for photoionization of the ground state, thereby the presence of metastable states in the ion beam may not be the reason for the enhancement of the measured cross sections.

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Measurements of the absolute photoionization cross section of Feions from 15.8 to 180 eV

Cited by 36 publications

References 36 publications

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

The [Feiv] Discrepancy: Constraining the Iron Abundances in Nebulae

Photoionization ofFe7+from the ground and metastable states

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Measurements of the absolute photoionization cross section of Fe ions from 15.8 to 180 eV

Cited by 36 publications

References 36 publications

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$ and Ne$\mathsf{^{4+}}$

The [Feiv] Discrepancy: Constraining the Iron Abundances in Nebulae

Photoionization ofFe7+from the ground and metastable states

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Measurements of the absolute photoionization cross section of Feions from 15.8 to 180 eV