Absolute cross sections for photoionization of Xeq +ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

Schippers, S.; Ricz, S.; Buhr, T.; Borovik, A.; Hellhund, J.; Holste, K.; Huber, Klaus; Schäfer, Hartmut; Schury, D.; Klumpp, S.; Mertens, K.; Martins, M.; Flesch, R.; Ulrich, G.; Rühl, E.; Jahnke, T.; Lower, Julian; Metz, D.; Schmidt, L. Ph. H.; Schöffler, M. S.; Williams, Joshua; Glaser, Leif; Scholz, Frank; Seltmann, Joern; Viefhaus, Jens; Dorn, Alexander; Wolf, A.; Ullrich, J.; Müller, A.

doi:10.1088/0953-4075/47/11/115602

Cited by 63 publications

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“…For the present experiment the photon-ion mergedbeams technique was employed using the permanently installed end station PIPE [16] at the "Variable Polarization XUV Beamline" (P04) [17] of the synchrotron light source PETRA III at DESY in Hamburg, Germany. Negatively charged oxygen ions were produced from a gas mixture of O 2 and He in an electron-cyclotron resonance (ECR) ion source.…”

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confidence: 99%

“…Relative cross sections for photodetachment were obtained by normalizing the measured product-ion count rates on photon flux and ion current. The relative cross sections were put on an absolute scale by additionally measuring the spatial overlap of photon and ion beams [16]. Because this procedure is rather time consuming it has been carried out only for one photon energy, and the relative cross sections were scaled to the absolute data points as shown in Fig.…”

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confidence: 99%

“…The photon energy scale was calibrated with an uncertainty of ±0.1 eV by remeasuring the 1s → π * resonance in O 2 at 531.06 ± 0.09 eV [19]. After this calibration of the nominal photon energy scale a Doppler correction was applied for taking the velocity of the O − ions into account [16]. Figure 1 displays the measured cross sections for double (upper panel) and triple (lower panel) photodetachment of O − .…”

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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

et al. 2016

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“…Here, recent first results on deep inner-shell photoionization and photofragmentation of Lu 3 N@C 80 endohedral fullerene ions [11] are featured. The results were obtained at the new photon-ion spectrometer PIPE (Photon-Ion Spectrometer at PETRA III) [12] at the beamline P04 [13] of the synchrotron light source PETRA III in Hamburg, Germany. This beamline offers record-high photon flux in the 250-3000 eV photon-energy range and, therefore, facilitates ionization of the carbon and nitrogen K-shells, as well as the lutetium M-shell.…”

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“…In this respect, the photon-ion merged-beams technique is very similar to Near-Edge X-ray Absorption Fine Structure (NEXAFS) [14] and, in the same way, allows the chemical environment of the atomic species under study to be probed. Figure 1 shows a sketch of the photon-ion merged-beams setup PIPE [12]. This setup is a permanently installed user facility at the variable polarization Extreme Ultra-Violet (XUV) beam line P04 [13] of the PETRA III synchrotron light source operated by DESY in Hamburg, Germany.…”

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

Schippers

2016

Condensed Matter

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Vibrationally Resolved Inner‐Shell Photoexcitation of the Molecular Anion C₂⁻

Schippers

Hillenbrand

Perry‐Sassmannshausen

et al. 2023

ChemPhysChem

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Carbon 1s core-hole excitation of the molecular anion C 2 À has been experimentally studied at high resolution by employing the photon-ion merged-beams technique at a synchrotron light source. The experimental cross section for photo-doubledetachment shows a pronounced vibrational structure associated with 1s u ! 3s g and 1s g ! 1p u core excitations of the C 2 À ground level and first excited level, respectively. A detailed Franck-Condon analysis reveals a strong contraction of the C 2 À molecular anion by 0.2 Å upon this core photoexcitation. The associated change of the molecule's moment of inertia leads to a noticeable rotational broadening of the observed vibrational spectral features. This broadening is accounted for in the present analysis which provides the spectroscopic parameters of the C 2 À 1s À 1 u 3s 2 g 2 S þ u and 1s À 1 g 3s 2 g 2 S þ g core-excited levels.

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Absolute cross sections for photoionization of Xe^{q +}ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

Abstract: Abstract.The photon-ion merged-beams technique has been employed at the new PhotonIon spectrometer at PETRA III (PIPE) for measuring multiple photoionization of Xe Absolute cross sections for 3d photoionization of Xe q+ ions (1 ≤ q ≤ 5) 2

Cited by 63 publications

References 55 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

Vibrationally Resolved Inner‐Shell Photoexcitation of the Molecular Anion C₂⁻

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Absolute cross sections for photoionization of Xeq +ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

Abstract: Abstract.The photon-ion merged-beams technique has been employed at the new PhotonIon spectrometer at PETRA III (PIPE) for measuring multiple photoionization of Xe Absolute cross sections for 3d photoionization of Xe q+ ions (1 ≤ q ≤ 5) 2

Cited by 63 publications

References 55 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

Vibrationally Resolved Inner‐Shell Photoexcitation of the Molecular Anion C2−

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Absolute cross sections for photoionization of Xe^{q +}ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

Vibrationally Resolved Inner‐Shell Photoexcitation of the Molecular Anion C₂⁻