Photoionisation of ions with synchrotron radiation: from ions in space to atoms in cages

Schippers, S.; Kilcoyne, A. L. D.; Phaneuf, R. A.; Müller, A.

doi:10.1080/00107514.2015.1109771

Cited by 60 publications

(66 citation statements)

References 82 publications

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“…Here, we apply the photon-ion merged-beams technique (see [9] for a recent overview) to determine the absolute cross sections for double and triple ionization (detachment) of oxygen anions in the photon energy range 524-543 eV. In this energy range, a K-shell vacancy may be produced either by direct ionization of an initial 1s electron or via the formation of a resonance state by exciting one 1s electron to a higher shell such as 2p.…”

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Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

et al. 2016

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The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O − ions. The experimental photon energy range of 524-543 eV comprised the threshold for K-shell ionization. Using resolving powers of up to 13000, the position, strength and width of the below-threshold 1s 2s 2 2p 6 2 S resonance as well as the positions of the 1s 2s 2 2p 5 3 P and 1s 2s 2 2p 5 1 P thresholds for K-shell ionization were determined with high-precision. In addition, systematically enlarged multi-configuration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these abinitio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shake-up (and -down) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy between measurements and theory is confirmed. Negative atomic ions play an important role in lowtemperature plasmas such as the upper atmosphere or the interstellar medium [1] and also in technical applications. For example, in the context of antihydrogen production, it has been proposed to use an ensemble of laser-cooled anions as a coolant for antiprotons [2]. Negative ions are fundamentally different from neutral atoms or positive ions since the extra electron in a negative ion is not only bound by the long-range Coulomb interaction with the atomic nucleus but, more importantly, also by a short-range attractive force due to the polarization of the atomic core. The accurate theoretical description of these ions still challenges the state-of-the-art quantum computations although the numbers of their bound states are generally finite. The low-excitation levels of negative ions are readily accessible by laser spectroscopy (see, e.g., [3][4][5][6]). Therefore, this technique has been a prime source of experimental information about the mutual interactions among the valence electrons.A sensitive tool for studying the interactions between the valence and the core electrons is inner-shell ionization of negative ions [7,8]. Here, we apply the photon-ion merged-beams technique (see [9] for a recent overview) to determine the absolute cross sections for double and triple ionization (detachment) of oxygen anions in the photon energy range 524-543 eV. In this energy range, a K-shell vacancy may be produced either by direct ionization of an initial 1s electron or via the formation of a resonance state by exciting one 1s electron to a higher shell such as 2p. In either case, the K-vacancy decays subsequently by a cascade of radiative and nonradiative processes leading to a distribution of final charge states with O + and O 2+ as the most prominent charged reaction products. To test and better understand the theoretical prediction of such cascades, we performed extremely comprehensive quantum calculations for the formation...

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Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

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“…The ion yields are all on the same relative cross-section scale. In principle, the photon-ion merged-beams method can be used to determine absolute cross sections [3,12]; however, this has not been pursued in the here-discussed experiments due to time constraints. The total number of possible product channels is much larger than what is depicted in Figure 3.…”

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“…Ion-yield spectra (which are not displayed here) were taken for heavy photo products ranging from Lu 3 . None of the corresponding spectra exhibited any sign of these edges.…”

Section: Resultsmentioning

confidence: 99%

“…During this period of time, most lighter fractions of the sample evaporated. Therefore, the mass/charge spectrum primarily exhibits mass/charge peaks due to singly, doubly, and triply charged intact Lu 3 Figure 2. Primary-ion mass spectrum with a mixture of Lu 3 N@C 80 (35%) and other fullerenes (65%, mainly C 60 ) in the ion source [11].…”

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“…As compared to spectroscopy of a neutral gas target, the photon-ion merged-beams technique (see [3] for a recent introductory review and Section 2 below) is a significantly different experimental approach which also permits sensitive measurements of photo-ion yields when only small amounts of low-purity sample material are available. Based on previous experience with empty fullerenes [4][5][6], a Gießen-Reno-Advanced Light Source (ALS) collaboration applied the photon-ion merged-beams method successfully for photoionization and photofragmentation studies with the endohedral fullerene ions Sc 3 N@C + 80 [7], Ce@C + 82 [8], and Xe@C + 60 [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Inner-Shell Ionization and Fragmentation of Isolated Endohedral Fullerene Ions by XUV Radiation

Schippers

2016

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The photon‐ion merged‐beams experiment PIPE at PETRA III—The first five years

et al. 2019

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The Photon-Ion Spectrometer at PETRA III -in short, PIPE -is a permanently installed user facility at the "Variable Polarization XUV Beamline" P04 of the synchrotron light source PETRA III operated by DESY in Hamburg, Germany. The careful design of the PIPE ion-optics in combination with the record-high photon flux at P04 has lead to a breakthrough in experimental studies of photon interactions with ionized small quantum systems. This short review provides an overview over the published scientific results from photon-ion merged-beams experiments at PIPE that were obtained since the start of P04 operations in 2013. The topics covered comprise photoionization of ions of astrophysical relevance, quantitative studies of multi-electron processes upon inner-shell photoexcitation and photoionization of negative and positive atomic ions, precision spectroscopy of photoionization resonances, photoionization and photofragmentation of molecular ions and of endohedral fullerene ions.

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Photoionisation of ions with synchrotron radiation: from ions in space to atoms in cages

Cited by 60 publications

References 82 publications

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

Inner-Shell Ionization and Fragmentation of Isolated Endohedral Fullerene Ions by XUV Radiation

The photon‐ion merged‐beams experiment PIPE at PETRA III—The first five years

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