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| 2. |
- Kosugi, S., et al.
(författare)
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Postcollision-interaction effects in multistep Auger transitions following Ar 1s photoionization
- 2022
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 106:3
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Tidskriftsartikel (refereegranskat)abstract
- Postcollision-interaction (PCI) effects involving multistep decay processes following Ar 1s photoionization has been studied by Auger electron spectroscopy. The experiment focused on LMM Auger electrons measured in small photon energy steps across the Ar 1s photoionization threshold. Decay pathways that we studied include (1) the Ar+*2p-1 -> Ar2+3p-2 LMM alpha Auger process due to a single L hole created by KL fluorescence, (2) the Ar2+*2p-2 -> Ar3+*2p-13p-2 LMM1 Auger process following double L shell hole states produced by a KLL Auger processes, and (3) the subsequent Ar3+*2p-13p-2 -> Ar4+3p-4 LMM2 Auger transitions. Particularly pronounced PCI shifts and unusual line shapes compared to the ordinary one-step PCI process were found in the spectra of Auger processes following a KLL Auger first step. The experimental results were compared with calculations based on the semiclassical approach to PCI. Good agreement was found between the calculated and experimental PCI shifts. The result opens possibilities for further studies of the multielectron dynamics between Auger electrons mediated through the photoelectron in these and similar systems.
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| 3. |
- Mailhiot, M., et al.
(författare)
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Multielectron coincidence spectroscopy of the Ar2+(2p-2) double-core-hole decay
- 2023
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Ingår i: Physical Review A. - 2469-9926. ; 107:6
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Tidskriftsartikel (refereegranskat)abstract
- The dominant decay pathways of argon 2p-2 double-core-hole states have been investigated using synchrotron radiation and a magnetic-bottle-type spectrometer coupled with an ion time-of-flight spectrometer. This experiment allows for efficient multi-electron-ion coincidence measurements, and thus for following the Auger cascade step by step in detail. Dominant decay pathways leading to Ar4+ final states via Ar3+ intermediate states have been assigned with the help of theoretical ab initio calculations. The weak correlated decay of the two core holes by emission of a single Auger electron, leading to Ar3+ final states, has been observed at 458.5-eV kinetic energy. Compared to the total decay of the 2p-2 double core vacancies, this two-electron-one-electron process was measured to have a branching ratio of 1.9 x 10-3 & PLUSMN; 1.0 x 10-3. Furthermore, the remaining decay paths of the Ar1+ (1s-1) core hole to higher charge states and their respective contributions to the total yield have been analyzed and show very good agreement with theoretical results.
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| 4. |
- Boonen, Annelies, et al.
(författare)
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EULAR Points to Consider (PtC) for designing, analysing and reporting of studies with work participation as an outcome domain in patients with inflammatory arthritis
- 2021
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ Publishing Group Ltd. - 0003-4967 .- 1468-2060. ; 80:9, s. 1116-1123
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Clinical studies with work participation (WP) as an outcome domain pose particular methodological challenges that hamper interpretation, comparison between studies and meta-analyses.OBJECTIVES: To develop Points to Consider (PtC) for design, analysis and reporting of studies of patients with inflammatory arthritis that include WP as a primary or secondary outcome domain.METHODS: The EULAR Standardised Operating Procedures were followed. A multidisciplinary taskforce with 22 experts including patients with rheumatic diseases, from 10 EULAR countries and Canada, identified methodologic areas of concern. Two systematic literature reviews (SLR) appraised the methodology across these areas. In parallel, two surveys among professional societies and experts outside the taskforce sought for additional methodological areas or existing conducting/reporting recommendations. The taskforce formulated the PtC after presentation of the SLRs and survey results, and discussion. Consensus was obtained through informal voting, with levels of agreement obtained anonymously.RESULTS: Two overarching principles and nine PtC were formulated. The taskforce recommends to align the work-related study objective to the design, duration, and outcome domains/measurement instruments of the study (PtC: 1-3); to identify contextual factors upfront and account for them in analyses (PtC: 4); to account for interdependence of different work outcome domains and for changes in work status over time (PtC: 5-7); to present results as means as well as proportions of patients reaching predefined meaningful categories (PtC: 8) and to explicitly report volumes of productivity loss when costs are an outcome (PtC:9).CONCLUSION: Adherence to these EULAR PtC will improve the methodological quality of studies evaluating WP.
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| 5. |
- Guillemin, R., et al.
(författare)
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Isotope effects in dynamics of water isotopologues induced by core ionization at an x-ray free-electron laser
- 2023
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Ingår i: STRUCTURAL DYNAMICS-US. - 2329-7778. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Dynamical response of water exposed to x-rays is of utmost importance in a wealth of science areas. We exposed isolated water isotopologues to short x-ray pulses from a free-electron laser and detected momenta of all produced ions in coincidence. By combining experimental results and theoretical modeling, we identify significant structural dynamics with characteristic isotope effects in H2O2+, D2O2+, and HDO2+, such as asymmetric bond elongation and bond-angle opening, leading to two-body or three-body fragmentation on a timescale of a few femtoseconds. A method to disentangle the sequences of events taking place upon the consecutive absorption of two x-ray photons is described. The obtained deep look into structural properties and dynamics of dissociating water isotopologues provides essential insights into the underlying mechanisms.
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| 6. |
- Jahnke, T., et al.
(författare)
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Inner-Shell-Ionization-Induced Femtosecond Structural Dynamics of Water Molecules Imaged at an X-Ray Free-Electron Laser
- 2021
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Ingår i: Physical Review X. - : American Physical Society. - 2160-3308. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated water molecules to a short x-ray pulse from a free-electron laser and detected momenta of all produced ions in coincidence. By combining experimental results and theoretical modeling, we can image dissociation dynamics of individual molecules in unprecedented detail. We reveal significant molecular structural dynamics in H2O2+, such as asymmetric deformation and bond-angle opening, leading to two-body or three-body fragmentation on a timescale of a few femtoseconds. We thus reconstruct several snapshots of structural dynamics at different time intervals, which highlight dynamical patterns that are relevant as initiating steps of subsequent radiation-damage processes.
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| 7. |
- Kosugi, S., et al.
(författare)
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Fluorescence Time Delay in Multistep Auger Decay as an Internal Clock
- 2020
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 124:18
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Tidskriftsartikel (refereegranskat)abstract
- Differences in postcollision interaction (PCI) effects on Kr L3M4.5M4.5 Auger electron spectra were observed, depending on whether the initial photoionization occurred slightly above the K threshold or slightly above the L-3 threshold. For the former, KL fluorescence emission most likely happens and then Auger processes due to the L-3 hole follow. The time delay due to fluorescence causes a reduced shift of the Auger peak and tailing toward lower energy, since the Auger overtaking of the photoelectron happens later in time and at a location farther away from the ionic core, compared to the case for the simple one-step L3M4.5M4.5 Auger decay after L-shell photoionization. Time-dependent theory for PCI in multistep processes agrees well with experiment, illustrating the effect as an internal clock for the time-sequence of the dynamical process.
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| 8. |
- Martins, J. B., et al.
(författare)
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Electron delocalisation in conjugated sulfur heterocycles probed by resonant Auger spectroscopy
- 2022
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:14, s. 8477-8487
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel approach for an indirect probing of conjugation and hyperconjugation in core-excited molecules using resonant Auger spectroscopy. Our work demonstrates that the changes in the electronic structure of thiophene (C4H4S) and thiazole (C3H3NS), occurring in the process of resonant sulfur K-shell excitation and Auger decay, affect the stabilisation energy resulting from pi-conjugation and hyperconjugation. The variations in the stabilisation energy manifest themselves in the resonant S KL2,3L2,3 Auger spectra of thiophene and thiazole. The comparison of the results obtained for the conjugated molecules and for thiolane (C4H8S), the saturated analogue of thiophene, has been performed. The experimental observations are interpreted using high-level quantum-mechanical calculations and the natural bond orbital analysis.
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| 9. |
- Püttner, R., et al.
(författare)
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Argon KLL Auger spectrum: Initial states, core-hole lifetimes, shake, and knock-down processes
- 2020
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Ingår i: Physical Review A. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 102:5
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Tidskriftsartikel (refereegranskat)abstract
- State-of-the-art argon KLL Auger spectra measured using photon energies of hν=3216 and 3400 eV are presented along with an Ar [1s] photoelectron spectrum (square brackets indicate holes in the respective orbital). The two different photon energies used for measuring the Auger spectra allow distinguishing between the shake transitions during the Auger decay and the Auger transitions of the photoelectron satellites. A complete assignment of satellite transitions is provided, partially based on configuration-interaction calculations. In addition, Ar [1s3(s,p)]n′l′→[2p2(1D2)] transitions are observed, which can be explained by knock-down transitions leading to a direct exchange of angular momentum between the excited electron and the Auger electron. The lifetime broadenings of the Ar [2s] single-core-hole state and the [2s2] and [2s2p] double-core-hole states are also determined, confirming previously observed trends for double-core-hole states. © 2020 American Physical Society.
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| 10. |
- Santos, A. C. F., et al.
(författare)
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Resonant Auger decay induced by the symmetry-forbidden 1a(1g)? 6a(1g) transition of the SF6 molecule
- 2022
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Ingår i: Journal of Vacuum Science & Technology A. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 40:4
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Tidskriftsartikel (refereegranskat)abstract
- Resonant Auger electron spectroscopic study at the symmetry-forbidden 1 a 1 g -> 6 a 1 g excitation below the S K-shell threshold of SF 6 is reported. Partial electron yield and resonant K L L Auger spectra have been measured by using monochromatized undulator synchrotron radiation. By changing the photon energy in small steps, a so-called 2D map is produced. In this map, the dipole-forbidden transition exhibits spectral features (e.g., an S-shaped dispersion relation), which are well known and understood for dipole-allowed transitions. We validate by a theory that for the case of dipole-forbidden transitions, these spectral features can be analyzed in the same way as previously established for the dipole-allowed ones. This approach grants information on the nuclear dynamics in the K-shell core-excited states of SF 6 on the femtosecond (fs) timescale. In particular, for the potential-energy curves of the states S 1 s(-1) 6(a1g) and S 2p(-2)6a(1g), the slopes at the equilibrium distance of the ground state are derived. Symmetry breaking as a result of ultrafast vibronic coupling is revealed by the population of the electronically forbidden excited state. Published under an exclusive license by the AVS.
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