Photoionization of Astrophysically Relevant Atomic Ions at PIPE

Schippers, S.; Müller, A.

doi:10.3390/atoms8030045

Cited by 12 publications

(9 citation statements)

References 109 publications

(127 reference statements)

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“…The experiment was performed at the end station PIPE (Schippers et al 2014;Müller et al 2017; of the photon beamline P04 (Viefhaus et al 2013) at the synchrotron light source PETRA III, which is operated by DESY in Hamburg, Germany. As for our previous work on L-shell photoionization of Fe + and Fe 3+ (Schippers et al 2017;Beerwerth et al 2019), we have employed the photon-ion merged-beams technique (for recent overviews, see Schippers et al 2016b;Schippers & Müller 2020) to measure cross sections for single and multiple photoionization of Fe 2+ ions. The experimental photon-energy range was 690-920eV.…”

Section: Methodsmentioning

confidence: 99%

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Schippers

Martins

Beerwerth³

et al. 2021

ApJ

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Using the photon-ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe 2+ ions in the energy range of 690-920eV. This range contains thresholds and resonances associated with ionization and excitation of 2p and 2s electrons. Calculations were performed to simulate the total absorption spectra. The theoretical results show very good agreement with the experimental data, if overall energy shifts of up to 2.5eV are applied to the calculated resonance positions and assumptions are made about the initial experimental population of the various levels of the Fe 2+ ([Ar]3d 6 ) ground configuration. Furthermore, we performed extensive calculations of the Auger cascades that result when an electron is removed from the 2p subshell of Fe 2+ . These computations lead to a better agreement with the measured product-charge-state distributions as compared to earlier work. We conclude that the L-shell absorption features of low-charged iron ions are useful for identifying gas-phase iron in the interstellar medium and for discriminating against the various forms of condensed-phase iron bound to composite interstellar dust grains.Unified Astronomy Thesaurus concepts: Interstellar atomic gas (833); Interstellar clouds (834); Interstellar medium (847); Interstellar absorption (831); Line intensities (2084); Atomic spectroscopy (2099); Line positions (2085); X-ray astronomy (1810); Laboratory astrophysics (2004)

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Section: Methodsmentioning

confidence: 99%

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Schippers

Martins

Beerwerth³

et al. 2021

ApJ

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“…Because of the many-body nature of the theoretical problem, the theoretical calculations have to resort to approximations yielding results that bear (usually unknown) uncertainties. In this situation, benchmarking by laboratory experiments (Schippers & Müller 2020) is vital for arriving at sufficiently accurate results that allow one, in the present context, to reliably discriminate between the gaseous and solid components of the ISM.…”

Section: Introductionmentioning

confidence: 99%

Near K-edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

Schippers

Stock

Buhr

et al. 2022

ApJ

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Experimental and theoretical results are presented for double, triple, and quadruple photoionization of Si+ and Si2+ ions and for double photoionization of Si3+ ions by a single photon. The experiments employed the photon–ion merged-beams technique at a synchrotron light source. The experimental photon-energy range 1835–1900 eV comprises resonances associated with the excitation of a 1s electron to higher subshells and subsequent autoionization. Energies, widths, and strengths of these resonances are extracted from high-resolution photoionization measurements, and the core-hole lifetime of K-shell ionized neutral silicon is inferred. In addition, theoretical cross sections for photoabsorption and multiple photoionization were obtained from large-scale multiconfiguration Dirac–Hartree–Fock calculations. The present calculations agree with the experiment much better than previously published theoretical results. The importance of an accurate energy calibration of laboratory data is pointed out. The present benchmark results are particularly useful for discriminating between silicon absorption in the gaseous and in the solid component (dust grains) of the interstellar medium.

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“…Because of the many-body nature of the theoretical problem the theoretical calculations have to resort to approximations yielding results that bear (usually unknown) uncertainties. In this situation, benchmarking by laboratory experiments (Schippers & Müller 2020) is vital for arriving at suffi-ciently accurate results that allow one, in the present context, to reliably discriminate between the gaseous and solid components of the ISM.…”

Section: Introductionmentioning

confidence: 99%

Near K-Edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

Schippers,

Stock,

Buhr

et al. 2022

Preprint

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Experimental and theoretical results are presented for double, triple, and quadruple photoionization of Si + and Si 2+ ions and for double photoionization of Si 3+ ions by a single photon. The experiments employed the photon-ion merged-beams technique at a synchrotron light source. The experimental photon-energy range 1835-1900 eV comprises resonances associated with the excitation of a 1s electron to higher subshells and subsequent autoionization. Energies, widths, and strengths of these resonances are extracted from high-resolution photoionization measurements, and the core-hole lifetime of K-shell ionized neutral silicon is inferred. In addition, theoretical cross sections for photoabsorption and multiple photoionization were obtained from large-scale Multi-Configuration Dirac-Hartree-Fock (MCDHF) calculations. The present calculations agree with the experiment much better than previously published theoretical results. The importance of an accurate energy calibration of laboratory data is pointed out. The present benchmark results are particularly useful for discriminating between silicon absorption in the gaseous and in the solid component (dust grains) of the interstellar medium.

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Photoionization of Astrophysically Relevant Atomic Ions at PIPE

Cited by 12 publications

References 109 publications

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Near K-edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

Near K-Edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

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