1. |
- Abe, K., et al.
(author)
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J-PARC Neutrino Beamline Upgrade Technical Design Report
- 2019
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Reports (peer-reviewed)abstract
- In this document, technical details of the upgrade plan of the J-PARC neutrino beamline for the extension of the T2K experiment are described. T2K has proposed to accumulate data corresponding to 2×1022 protons-on-target in the next decade, aiming at an initial observation of CP violation with 3σ or higher significance in the case of maximal CP violation. Methods to increase the neutrino beam intensity, which are necessary to achieve the proposed data increase, are described.
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2. |
- Abele, H., et al.
(author)
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Particle physics at the European Spallation Source
- 2023
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In: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
-
Research review (peer-reviewed)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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3. |
- Jahnke, T., et al.
(author)
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Inner-Shell-Ionization-Induced Femtosecond Structural Dynamics of Water Molecules Imaged at an X-Ray Free-Electron Laser
- 2021
-
In: Physical Review X. - : American Physical Society. - 2160-3308. ; 11:4
-
Journal article (peer-reviewed)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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4. |
- Bolognesi, P., et al.
(author)
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A study of the dynamical energy flow in uracil
- 2015
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In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
-
Journal article (peer-reviewed)abstract
- The time resolved photoionization of C 1s in uracil following excitation of the neutral molecule by 260 nm pulses has been studied at LCLS.
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5. |
- Gomes, CPC, et al.
(author)
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Catalyzing Transcriptomics Research in Cardiovascular Disease: The CardioRNA COST Action CA17129
- 2019
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In: Non-coding RNA. - : MDPI AG. - 2311-553X. ; 5:2
-
Journal article (peer-reviewed)abstract
- Cardiovascular disease (CVD) remains the leading cause of death worldwide and, despite continuous advances, better diagnostic and prognostic tools, as well as therapy, are needed. The human transcriptome, which is the set of all RNA produced in a cell, is much more complex than previously thought and the lack of dialogue between researchers and industrials and consensus on guidelines to generate data make it harder to compare and reproduce results. This European Cooperation in Science and Technology (COST) Action aims to accelerate the understanding of transcriptomics in CVD and further the translation of experimental data into usable applications to improve personalized medicine in this field by creating an interdisciplinary network. It aims to provide opportunities for collaboration between stakeholders from complementary backgrounds, allowing the functions of different RNAs and their interactions to be more rapidly deciphered in the cardiovascular context for translation into the clinic, thus fostering personalized medicine and meeting a current public health challenge. Thus, this Action will advance studies on cardiovascular transcriptomics, generate innovative projects, and consolidate the leadership of European research groups in the field.COST (European Cooperation in Science and Technology) is a funding organization for research and innovation networks (www.cost.eu).
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6. |
- Carniato, S., et al.
(author)
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Photon-energy dependence of single-photon simultaneous core ionization and core excitation in CO2
- 2016
-
In: PHYSICAL REVIEW A. - 2469-9926. ; 94:1
-
Journal article (peer-reviewed)abstract
- We have studied the K-2V process corresponding to simultaneous K-shell ionization and K-shell excitation in the CO2 molecule. We define these K-2V states as super shake-up, at variance with the "conventional" K(-1)v(-1)V shake-up states. While the nature and evolution with photon energy of the conventional shake-up satellites has been the object of many studies, no such data on a large photon-energy range were previously reported on super shake-up. The CO2 molecule is a textbook example because it exhibits two well-isolated K-2V resonances (with V being 2 pi(u)* and 5 delta g*) with different symmetries resulting from shake-up processes of different origin populated in comparable proportions. The variation of the excitation cross section of these two resonances with photon energy is reported, using two different experimental approaches, which sheds light on the excitation mechanisms. Furthermore, double-core-hole spectroscopy is shown to be able to integrate and even expand information provided by conventional single-core-hole X-ray Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) techniques, revealing, for instance, g-g dipole forbidden transitions which are only excited in NEXAFS spectra through vibronic coupling.
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7. |
- Feifel, Raimund, et al.
(author)
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Cationic double K-hole pre-edge states of CS2 and SF6
- 2017
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
-
Journal article (peer-reviewed)abstract
- Recent advances in X-ray instrumentation have made it possible to measure the spectra of an essentially unexplored class of electronic states associated with double inner-shell vacancies. Using the technique of single electron spectroscopy, spectra of states in CS2 and SF6 with a double hole in the K-shell and one electron exited to a normally unoccupied orbital have been obtained. The spectra are interpreted with the aid of a high-level theoretical model giving excellent agreement with the experiment. The results shed new light on the important distinction between direct and conjugate shake-up in a molecular context. In particular, systematic similarities and di erences between pre-edge states near single core holes investigated in X-ray absorption spectra and the corresponding states near double core holes studied here are brought out.
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8. |
- Frasinski, L. J., et al.
(author)
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Dynamics of Hollow Atom Formation in Intense X-Ray Pulses Probed by Partial Covariance Mapping
- 2013
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:7, s. 073002-
-
Journal article (peer-reviewed)abstract
- When exposed to ultraintense x-radiation sources such as free electron lasers (FELs) the innermost electronic shell can efficiently be emptied, creating a transient hollow atom or molecule. Understanding the femtosecond dynamics of such systems is fundamental to achieving atomic resolution in flash diffraction imaging of noncrystallized complex biological samples. We demonstrate the capacity of a correlation method called partial covariance mapping'' to probe the electron dynamics of neon atoms exposed to intense 8 fs pulses of 1062 eV photons. A complete picture of ionization processes competing in hollow atom formation and decay is visualized with unprecedented ease and the map reveals hitherto unobserved nonlinear sequences of photoionization and Auger events. The technique is particularly well suited to the high counting rate inherent in FEL experiments.
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9. |
- Goldsztejn, G., 2017, et al.
(author)
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Experimental and theoretical study of the double-core-hole hypersatellite Auger spectrum of Ne
- 2017
-
In: Physical Review A. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 96
-
Journal article (peer-reviewed)abstract
- We present the hypersatellite Auger spectrum of neon which contains the decay transitions of the K−2, K−2V, K−2L−1, K−2L−1V, and K−1L−1V states. The Auger decays of these types of core-hole states show different line shapes and linewidths which can be distinguished due to the high experimental resolution available for the present experiments. The individual Auger transitions are assigned based on various approaches. Complementary calculations are performed to assign the K−2L−1 → K−1L−3 and the K−2L−1V → K−1L−3V Auger transitions. Based on the obtained results we were able to derive the ratio for the double to single ionization yield.
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10. |
- Guillemin, R., et al.
(author)
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Selecting core-hole localization or delocalization in CS2 by photofragmentation dynamics
- 2015
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
-
Journal article (peer-reviewed)abstract
- Electronic core levels in molecules are highly localized around one atomic site. However, in single-photon ionization of symmetric molecules, the question of core-hole localization versus delocalization over two equivalent atoms has long been debated as the answer lies at the heart of quantum mechanics. Here, using a joint experimental and theoretical study of core-ionized carbon disulfide (CS2), we demonstrate that it is possible to experimentally select distinct molecular-fragmentation pathways in which the core hole can be considered as either localized on one sulfur atom or delocalized between two indistinguishable sulfur atoms. This feat is accomplished by measuring photoelectron angular distributions within the frame of the molecule, directly probing entanglement or disentanglement of quantum pathways as a function of how the molecule dissociates.
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11. |
- Mucke, Melanie, et al.
(author)
-
Covariance mapping of two-photon double core hole states in C2H2 and C2H6 produced by an x-ray free electron laser
- 2015
-
In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 17
-
Journal article (peer-reviewed)abstract
- Few-photon ionization and relaxation processes in acetylene (C2H2) and ethane (C2H6) were investigated at the linac coherent light source x-ray free electron laser (FEL) at SLAC, Stanford using a highly efficient multi-particle correlation spectroscopy technique based on a magnetic bottle. The analysis method of covariance mapping has been applied and enhanced, allowing us to identify electron pairs associated with double core hole (DCH) production and competing multiple ionization processes including Auger decay sequences. The experimental technique and the analysis procedure are discussed in the light of earlier investigations of DCH studies carried out at the same FEL and at third generation synchrotron radiation sources. In particular, we demonstrate the capability of the covariance mapping technique to disentangle the formation of molecular DCH states which is barely feasible with conventional electron spectroscopy methods.
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12. |
- Squibb, Richard J., et al.
(author)
-
Acetylacetone photodynamics at a seeded free-electron laser
- 2018
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
-
Journal article (peer-reviewed)abstract
- Thefirst steps in photochemical processes, such as photosynthesis or animal vision, involvechanges in electronic and geometric structure on extremely short time scales. Time-resolvedphotoelectron spectroscopy is a natural way to measure such changes, but has been hinderedhitherto by limitations of available pulsed light sources in the vacuum-ultraviolet and soft X-ray spectral region, which have insufficient resolution in time and energy simultaneously. Theunique combination of intensity, energy resolution, and femtosecond pulse duration of theFERMI-seeded free-electron laser can now provide exceptionally detailed information onphotoexcitation–deexcitation and fragmentation in pump-probe experiments on the 50-femtosecond time scale. For the prototypical system acetylacetone we report here electronspectra measured as a function of time delay with enough spectral and time resolution tofollow several photoexcited species through well-characterized individual steps, interpretedusing state-of-the-art static and dynamics calculations. These results open the way forinvestigations of photochemical processes in unprecedented detail.
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13. |
- Zhaunerchyk, Vitali, et al.
(author)
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Using covariance mapping to investigate the dynamics of multi-photon ionization processes of Ne atoms exposed to X-FEL pulses
- 2013
-
In: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 46:16, s. 164034-
-
Journal article (peer-reviewed)abstract
- We report on a detailed investigation into the electron emission processes of Ne atoms exposed to intense femtosecond x-ray pulses, provided by the Linac Coherent Light Source Free Electron Laser (FEL) at Stanford. The covariance mapping technique is applied to analyse the data, and the capability of this approach to disentangle both linear and nonlinear correlation features which may be hidden on coincidence maps of the same data set is demonstrated. Different correction techniques which enable improvements on the quality of the spectral features extracted from the covariance maps are explored. Finally, a method for deriving characteristics of the x-ray FEL pulses based on covariance mapping in combination with model simulations is presented.
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14. |
- Allum, Felix, et al.
(author)
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Coulomb explosion imaging of CH3I and CH2CII photodissociation dynamics
- 2018
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 149:20
-
Journal article (peer-reviewed)abstract
- The photodissociation dynamics of CH3I and CH2CII at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815nmprobe pulse. Fragment ion momenta over a widem/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH2ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion.
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15. |
- Bowen, K. P., et al.
(author)
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Nondipole Effects in Chiral Molecules Measured with Linearly Polarized Light
- 2015
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
-
Journal article (peer-reviewed)abstract
- We present the first-ever measurement of nondipole chiral angular distribution parameters for C 1s photoemission from each enantiomer of camphor in the photon energy range 296-343eV using linearly polarized light. The angular distribution parameters are determined to be enantiomer-specific, suggesting a new form of linear dichroism.
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16. |
- Brasse, Felix, et al.
(author)
-
Time-resolved inner-shell photoelectron spectroscopy : From a bound molecule to an isolated atom
- 2018
-
In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 97:4
-
Journal article (peer-reviewed)abstract
- Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.
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17. |
- Burt, Michael, et al.
(author)
-
Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics
- 2017
-
In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 96:4
-
Journal article (peer-reviewed)abstract
- The dynamics following laser-induced molecular photodissociation of gas-phase CH2BrI at 271.6 nm were investigated by time-resolved Coulomb-explosion imaging using intense near-IR femtosecond laser pulses. The observed delay-dependent photofragment momenta reveal that CH2BrI undergoes C-I cleavage, depositing 65.6% of the available energy into internal product states, and that absorption of a second UV photon breaks the C-Br bond of C(H)2Br. Simulations confirm that this mechanism is consistent with previous data recorded at 248 nm, demonstrating the sensitivity of Coulomb-explosion imaging as a real-time probe of chemical dynamics.
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18. |
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19. |
- Ceolin, D., et al.
(author)
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Auger resonant-Raman study at the Ar K edge as probe of electronic-state-lifetime interferences
- 2015
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 91:2
-
Journal article (peer-reviewed)abstract
- The resonant-Auger decay in argon following Ar 1s - np excitations was studied under resonant-Raman conditions, i.e., with a total instrumental bandwidth much narrower than the natural linewidth of the absorption features. These state-of-the-art experiments are combined with a radiationless resonant-Raman scattering theory. The main results include identification of the energy position of some high-lying Rydberg states previously masked by insufficient resolution and clear evidence of electronic-state-lifetime interference phenomena.
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20. |
- Frede, Annika, et al.
(author)
-
B cell expansion hinders the stroma-epithelium regenerative cross talk during mucosal healing
- 2022
-
In: Immunity. - : Elsevier BV. - 1074-7613 .- 1097-4180. ; 55:12, s. 2336-
-
Journal article (peer-reviewed)abstract
- Therapeutic promotion of intestinal regeneration holds great promise, but defining the cellular mechanisms that influence tissue regeneration remains an unmet challenge. To gain insight into the process of mucosal healing, we longitudinally examined the immune cell composition during intestinal damage and regeneration. B cells were the dominant cell type in the healing colon, and single-cell RNA sequencing (scRNA-seq) re-vealed expansion of an IFN-induced B cell subset during experimental mucosal healing that predominantly located in damaged areas and associated with colitis severity. B cell depletion accelerated recovery upon injury, decreased epithelial ulceration, and enhanced gene expression programs associated with tissue re-modeling. scRNA-seq from the epithelial and stromal compartments combined with spatial transcriptomics and multiplex immunostaining showed that B cells decreased interactions between stromal and epithelial cells during mucosal healing. Activated B cells disrupted the epithelial-stromal cross talk required for orga-noid survival. Thus, B cell expansion during injury impairs epithelial-stromal cell interactions required for mucosal healing, with implications for the treatment of IBD.
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21. |
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22. |
- Ismail, I., et al.
(author)
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Experimental setup for the study of resonant inelastic X-ray scattering of organometallic complexes in gas phase
- 2018
-
In: Review of Scientific Instruments. - : AMER INST PHYSICS. - 0034-6748 .- 1089-7623. ; 89:6
-
Journal article (peer-reviewed)abstract
- A new setup has been designed and built to study organometallic complexes in gas phase at the third-generation Synchrotron radiation sources. This setup consists of a new homemade computer-controlled gas cell that allows us to sublimate solid samples by accurately controlling the temperature. This cell has been developed to be a part of the high-resolution X-ray emission spectrometer permanently installed at the GALAXIES beamline of the French National Synchrotron Facility SOLEIL. To illustrate the capabilities of the setup, the cell has been successfully used to record high-resolution K alpha emission spectra of gas-phase ferrocene Fe(C5H5)(2) and to characterize their dependence with the excitation energy. This will allow to extend resonant X-ray emission to different organometallic molecules.
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23. |
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24. |
- Kircher, Max, et al.
(author)
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Kinematically complete experimental study of Compton scattering at helium atoms near the threshold
- 2020
-
In: Nature Physics. - : Springer Nature. - 1745-2473 .- 1745-2481. ; 16:7, s. 756-760
-
Journal article (peer-reviewed)abstract
- Compton scattering is one of the fundamental interaction processes of light with matter. When discovered(1), it was described as a billiard-type collision of a photon 'kicking' a quasi-free electron. With decreasing photon energy, the maximum possible momentum transfer becomes so small that the corresponding energy falls below the binding energy of the electron. In this regime, ionization by Compton scattering becomes an intriguing quantum phenomenon. Here, we report on a kinematically complete experiment studying Compton scattering off helium atoms in that regime. We determine the momentum correlations of the electron, the recoiling ion and the scattered photon in a coincidence experiment based on cold target recoil ion momentum spectroscopy, finding that electrons are not only emitted in the direction of the momentum transfer, but that there is a second peak of ejection to the backward direction. This finding links Compton scattering to processes such as ionization by ultrashort optical pulses(2), electron impact ionization(3,4), ion impact ionization(5,6) and neutron scattering(7), where similar momentum patterns occur. Compton scattering experiments off helium atoms for photon energies close to the ionization threshold reveal that electrons are not only emitted in the direction of the momentum transfer but also backwards.
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25. |
- Kockert, Hansjochen, et al.
(author)
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UV-induced dissociation of CH2BrI probed by intense femtosecond XUV pulses
- 2022
-
In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 55:1
-
Journal article (peer-reviewed)abstract
- The ultraviolet (UV)-induced dissociation and photofragmentation of gas-phase CH2BrI molecules induced by intense femtosecond extreme ultraviolet (XUV) pulses at three different photon energies are studied by multi-mass ion imaging. Using a UV-pump-XUV-probe scheme, charge transfer between highly charged iodine ions and neutral CH2Br radicals produced by C-I bond cleavage is investigated. In earlier charge-transfer studies, the center of mass of the molecules was located along the axis of the bond cleaved by the pump pulse. In the present case of CH2BrI, this is not the case, thus inducing a rotation of the fragment. We discuss the influence of the rotation on the charge transfer process using a classical over-the-barrier model. Our modeling suggests that, despite the fact that the dissociation is slower due to the rotational excitation, the critical interatomic distance for charge transfer is reached faster. Furthermore, we suggest that charge transfer during molecular fragmentation may be modulated in a complex way.
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26. |
- Kukk, E., et al.
(author)
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Photoelectron recoil in CO in the x-ray region up to 7 keV
- 2017
-
In: PHYSICAL REVIEW A. - 2469-9926. ; 95:4
-
Journal article (peer-reviewed)abstract
- Carbon 1s photoelectron spectra of CO molecules in gas phase were recorded in the tender x-ray energy range, from 2.3 to 6.9 keV. The intensity ratios of individual peaks from nu = 0 to 3 within the vibrational progression of the C 1s photoelectron spectrum were determined at the various photon energies and are shown to be strongly affected by the photoelectron recoil effect. The experimental vibrational intensity ratios are compared with theoretical predictions at different levels of accuracy. Developments of the recoil model, using generalized Franck-Condon factors, rovibrational coupling, Morse potential energy curves, and accurate angular averaging are presented and applied to the analysis of the experimental results.
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27. |
- Kukk, E., et al.
(author)
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Unified treatment of recoil and Doppler broadening in molecular high-energy photoemission
- 2021
-
In: New Journal of Physics. - : Institute of Physics Publishing (IOPP). - 1367-2630. ; 23:6
-
Journal article (peer-reviewed)abstract
- Doppler and recoil effects are an integral part of the photoemission process at the high kinetic energies reached in hard x-ray photo-electron spectroscopy (HAXPES) and have a major effect on the observed lineshape, resulting in broadening, energy losses and discrete excitations. These effects can be modeled with a high degree of detail for small systems like diatomic molecules, for larger systems such treatment is often superfluous as the fine spectral features are not observable. We present a united description of the Doppler and recoil effects for arbitrary polyatomic systems and offer an approximate description of the recoil- and Doppler-modified photoemission spectral lineshape as a practical tool in the analysis of HAXPES spectra of core-level photoemission. The approach is tested on the examples of carbon dioxide and pentane molecules. The C and O 1s photoelectron spectra of CO2 in gas phase were also measured at 2.3 and 7.0 keV photon energy at Synchrotron SOLEIL and the spectra were analyzed using the model description. The limitations and applicability of the approach to adsorbates, interfaces and solids is briefly discussed.
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28. |
- Kushawaha, R. K., et al.
(author)
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Auger resonant-Raman decay after Xe L-edge photoexcitation
- 2015
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 92:1
-
Journal article (peer-reviewed)abstract
- We have investigated resonant Auger decay of xenon following photoexcitation of each of the three L edges under resonant-Raman conditions, which allowed us to characterize several higher Rydberg transitions. Relative intensities for spectator final states reached after L-1-, L-2-, and L-3-edge excitations are studied in detail. Thanks to state-of-the-art experimental arrangements, our results not only reproduce the previously calculated 3d(-2)5d and nd (n > 5) state cross sections after L-3 excitation, but also allow extracting the 3d(-2)6d spectator state energy position and revealing its resonant behavior, blurred by the insufficient experimental resolution in previous data sets. The 3d(-2)6p and 3d(-2)7p states reached after L-1 excitation as well as the 3d(-2)5d and 3d(-2)6d states reached after L-2 excitation are also investigated and their relative intensities are reported and compared to ab initio Dirac-Hartree-Fock configuration-interaction calculations. We found the signature of electronic-state-lifetime interference effects between several coherently excited intermediate states, due to large lifetime broadening. Electron recapture processes are also identified above all three photoionization thresholds.
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29. |
- Puettner, R., et al.
(author)
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Double core-hole states in SiX4 (X = F, Cl, Br, and CH3) molecules derived by photoelectron and KLL Auger spectroscopy
- 2015
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In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
-
Journal article (peer-reviewed)abstract
- In recent years double core-hole states are intensively studied since their chemical shifts provide detailed information about initial-state and relaxation effects in a molecule. We derived the Si 1 s(-1), 2s(-1) and 2p(-1) binding energies as well as the Si 2s(-2), 2(p-1)2p(-1), and 2p(-2) double-core hole binding energies of different SiX4 systems in order to derive the chemical shifts. Based on these results we created Wagner plots, which give insight in the initial state and the relaxation effects in the different molecules.
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30. |
- Püttner, R., et al.
(author)
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Argon KLL Auger spectrum: Initial states, core-hole lifetimes, shake, and knock-down processes
- 2020
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In: Physical Review A. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 102:5
-
Journal article (peer-reviewed)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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31. |
- Püttner, R., et al.
(author)
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Nonstatistical behavior of the photoionization of spin-orbit doublets
- 2021
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 54:8
-
Journal article (peer-reviewed)abstract
- The photoionization branching ratios of spin-orbit doublets are studied both experimentally and theoretically at energies several keV above threshold. The results show significant relativistic effects for Ar 2p in the autoionizing region below the 1s threshold, and large many-body effects for Xe 3d and 4d in the vicinity of the L-shell thresholds. The branching ratios in Xe are also found to vary significantly over very broad multi-keV energy regions both above and below the inner-shell thresholds. In addition, the Ar 2p study confirms experimentally the decades-old theoretical prediction that the nonresonant branching ratio does not approach the statistical (nonrelativistic) value, and, in fact, progressively diverges from statistical with increasing photon energy. © 2021 The Author(s). Published by IOP Publishing Ltd.
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32. |
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33. |
- Sahlén, Martin, et al.
(author)
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Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-Ray Free-Electron Laser
- 2012
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:15, s. 153003-
-
Journal article (peer-reviewed)abstract
- We have performed x-ray two-photon photoelectron spectroscopy using the Linac Coherent Light Source x-ray free-electron laser in order to study double core-hole (DCH) states of CO2, N2O, and N-2. The experiment verifies the theory behind the chemical sensitivity of two-site DCH states by comparing a set of small molecules with respect to the energy shift of the two-site DCH state and by extracting the relevant parameters from this shift.
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