R-Matrix Theory of Atomic and Molecular Processes

Burke, P G

doi:10.1007/978-1-4613-4202-1_18

Cited by 117 publications

(183 citation statements)

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“…Photoabsorption by Ne + ions near the K edge has been investigated theoretically by Gorczyca (2000), Juett et al (2006), and Gatuzz et al (2015), and by Witthoeft et al (2009), with both groups using R-matrix theory (Burke & Berrington 1993;Burke et al 2006, pp. 237-318).…”

Section: Comparison With Theorymentioning

confidence: 99%

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Müller

Bernhardt

Borovik

et al. 2017

ApJ

114

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Single, double, and triple photoionization of Ne + ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon-ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K-and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne + ( s s p 1 2 2 S 2 6 2 1 2 ) level, for example, requires cooperative interaction of at least four electrons.

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Section: Comparison With Theorymentioning

confidence: 99%

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Müller

Bernhardt

Borovik

et al. 2017

ApJ

114

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“…The scattering calculations were performed using R-matrix theory (Wigner & Eisenbud 1947;Burke & Berrington 1993) where the the intermediate-coupling frame transformation method (ICFT) of Griffin et al (1998) was used to simplify the inner region calculation. The details of the calculations follow closely to previous work on iron ions (cf.…”

Section: Calculationmentioning

confidence: 99%

Atomic data from the IRON Project

Witthoeft

Badnell

2008

A&A

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We present R-matrix results for the electron-impact excitation of Fe 6+ . The intermediate-coupling frame transformation (ICFT) method has been used to obtain level-resolved collision strengths. We then calculate effective collision strengths assuming a Maxwellian distribution for the incident electron velocities. A large configuration interaction (CI) expansion of 1896 LS terms (4776 fine-structure levels) is used to obtain an accurate target. This is reduced to 89 close-coupling (CC) terms (189 levels) for the scattering calculation. To investigate the importance of CI, we also perform a second calculation with the same CC expansion but a smaller CI expansion. We discuss the difficulties of such a comparison and look at which transitions show the most sensitivity to the CI expansion. Our effective collision strengths are compared with a previous IRON Project report (Berrington et al. 2000, A&A, 142, 313) for transitions within the ground configuration and a recent distorted wave calculation (Zeng et al. 2005, MNRAS, 357, 440) for transitions to excited configurations. We find good agreement with the results of the previous R-matrix calculation and with the high-temperature distorted-wave results for most transitions, although there are some significant differences at lower temperatures in the latter case.

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“…In R-matrix theory, all PI/photoabsorption calculations require the generation of atomic orbitals based primarily on the structure of the residual ion [6,65,66,78,79]. PI cross-section calculations for Be-like boron B + ions were performed in LS coupling within the confines of the R-matrix approach [1,6,65,66,78,79].…”

Section: R-matrixmentioning

confidence: 99%

“…In addition, when metastable states are present in the parent experimental ion beam, further theoretical calculations are necessary to determine their contribution, as in the present study for K-shell PI of Be-like boron B + ions. For handling all these requirements the state-of-the-art R-matrix method [65,66] was employed in the present study. The experimental techniques were the same as those used in the most recent experimental work at the ALS in PI studies on Be-like ions [67], multiply charged iron ions [68], singly charged argon [69] and singly charged krypton [70] ions.…”

Section: Introductionmentioning

confidence: 99%

K-shell photoionization of Be-like boron (B⁺) ions: experiment and theory

Müller¹,

Schippers²,

Phaneuf³

et al. 2014

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

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View the article online for updates and enhancements. AbstractAbsolute cross sections for the K-shell photoionization of Be-like boron ions were measured with the ion-photon merged-beams technique at the Advanced Light Source synchrotron radiation facility. High-resolution spectroscopy with E/ E up to 8800 ( E ∼ 22 meV) covered the energy ranges 193.7-194.7 eV and 209-215 eV. Lifetimes of the strongest resonances are determined with relative uncertainties down to approximately 4% for the broadest resonance. The measured resonance strengths are consistent with 60% 1s 2 2s 2 1 S ground-state and 40% 1s 2 2s2p 3 P o metastable-state ions in the primary ion beam and confirmed by comparison with independent absolute photo-recombination heavy-ion storage-ring measurements with B 2+ ions using the principle of detailed balance. Experimental determination of the line width for the 1s2s 2 2p 1 P o resonance gives a value of 47 ± 2 meV and compares favourably to a theoretical estimate of 47 meV from the R-matrix with pseudo-states (RMPS) method. The measured line widths of the 1s2s2p 2 3 P, 3 D resonances are 10.0 ± 2 meV and 32 ± 3 meV, respectively, compared to RMPS theoretical estimates of 9 meV and 34 meV.

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R-Matrix Theory of Atomic and Molecular Processes

Cited by 117 publications

References 43 publications

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Atomic data from the IRON Project

K-shell photoionization of Be-like boron (B⁺) ions: experiment and theory

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R-Matrix Theory of Atomic and Molecular Processes

Cited by 117 publications

References 43 publications

Photoionization of Ne Atoms and Ne+ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Photoionization of Ne Atoms and Ne+ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Atomic data from the IRON Project

K-shell photoionization of Be-like boron (B+) ions: experiment and theory

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Product

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Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

K-shell photoionization of Be-like boron (B⁺) ions: experiment and theory