| 1. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Ingle, R. A., et al.
(författare)
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Carbon K-edge x-ray emission spectroscopy of gas phase ethylenic molecules
- 2022
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 55:4
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Tidskriftsartikel (refereegranskat)abstract
- We report on the C K-edge x-ray absorption spectra and the resonant (RXES) and non-resonant (NXES) x-ray emission spectra of ethylene, allene and butadiene in the gas phase. The RXES and NXES show clear differences for the different molecules. Overall both types of spectra are more structured for ethylene and allene, than for butadiene. Using density functional theory–restricted open shell configuration interaction single calculations, we simulate the spectra with remarkable agreement with the experiment. We identify the spectral features as being due to transitions involving localised 1s orbitals. For allene, there are distinct spectral bands that reflect transitions predominantly from either the central or terminal carbon atoms. These results are discussed in the context of ultrafast x-ray studies aimed at detecting the passage through conical intersections in polyatomic molecules.
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| 4. |
- Makos, I., et al.
(författare)
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Attosecond photoelectron spectroscopy using high-harmonic generation and seeded free-electron lasers
- 2023
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Ingår i: 2023 Photonics North, PN 2023. - 9798350326734
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Konferensbidrag (refereegranskat)abstract
- In this work, we use attosecond time-resolved techniques to investigate photoionization dynamics on its natural timescale, employing both high harmonic generation and seeded free-electron lasers to generate extreme ultraviolet attosecond pulse trains for our studies. With the former approach, we examine the role of nuclear motion in molecular photoionization dynamics, while with the latter we introduce a novel attosecond timing tool for single-shot characterization of the relative phase between the XUV and the infrared field.
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| 5. |
- Maroju, Praveen Kumar, et al.
(författare)
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Attosecond coherent control of electronic wave packets in two-colour photoionization using a novel timing tool for seeded free-electron laser
- 2023
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 17, s. 200-207
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Tidskriftsartikel (refereegranskat)abstract
- In ultrafast spectroscopy, the temporal resolution of time-resolved experiments depends on the duration of the pump and probe pulses, and on the control and characterization of their relative synchronization. Free-electron lasers operating in the extreme ultraviolet and X-ray spectral regions deliver pulses with femtosecond and attosecond duration in a broad array of pump-probe configurations to study a wide range of physical processes. However, this flexibility, together with the large dimensions and high complexity of the experimental set-ups, limits control of the temporal delay to the femtosecond domain, thus precluding a time resolution below the optical cycle. Here we demonstrate a novel single-shot technique able to determine the relative synchronization between an attosecond pulse train-generated by a seeded free-electron laser-and the optical oscillations of a near-infrared field, with a resolution of one atomic unit (24 as). Using this attosecond timing tool, we report the first example of attosecond coherent control of photoionization in a two-colour field by manipulating the phase of high-order near-infrared transitions.
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| 6. |
- Coury, H. J. C. G., et al.
(författare)
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Change in knee kinematics during gait after eccentric isokinetic training for quadriceps in subjects submitted to anterior cruciate ligament reconstruction
- 2006
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Ingår i: Gait & Posture. - : Elsevier BV. - 1879-2219 .- 0966-6362. ; 24:3, s. 370-374
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Tidskriftsartikel (refereegranskat)abstract
- Knee kinematics after anterior cruciate ligament (ACL) reconstruction is of interest in studies evaluating the effect of training programs. Many studies have addressed knee flexion/extension but not valgus/varus movements. Considering that joint stability is a major concern in ACL reconstruction surgery, movements occurring in the frontal plane of the knee also deserve attention. Knee extensor torque was analyzed by an isokinetic dynamometer and the angular amplitudes and velocities of flexion/extension and valgus/varus movements were analyzed by goniometry during gait 9 months after ACL reconstruction. The analysis was repeated after 3 months of eccentric isokinefic training of the quadriceps in five patients. The gait pattern was also recorded for 10 healthy controls. The knee extensor torque and flexion/extension range of movement during gait increased significantly after training. However, an unexpectedly increased valgus, most pronounced during the swing phase, which may imply adverse effects on the knee, was also observed in the ACL reconstructed knee. The recorded valgus angles may however be overestimated due to crosstalk. Thus, the extent of the increased valgus, as well as the mechanisms involved and the functional and clinical implications, need clarification before eccentric training after ACL reconstruction can be generally recommended. (C) 2005 Elsevier B.V. All rights reserved.
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| 7. |
- Ertel, D., et al.
(författare)
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Ultrastable, high-repetition-rate attosecond beamline for time-resolved XUV-IR coincidence spectroscopy
- 2023
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Ingår i: Review of Scientific Instruments. - 0034-6748. ; 94:7
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Tidskriftsartikel (refereegranskat)abstract
- The implementation of attosecond photoelectron-photoion coincidence spectroscopy for the investigation of atomic and molecular dynamics calls for a high-repetition-rate driving source combined with experimental setups characterized by excellent stability for data acquisition over time intervals ranging from a few hours up to a few days. This requirement is crucial for the investigation of processes characterized by low cross sections and for the characterization of fully differential photoelectron(s) and photoion(s) angular and energy distributions. We demonstrate that the implementation of industrial-grade lasers, combined with a careful design of the delay line implemented in the pump-probe setup, allows one to reach ultrastable experimental conditions leading to an error in the estimation of the time delays of only 12 as over an acquisition time of 6.5 h. This result opens up new possibilities for the investigation of attosecond dynamics in simple quantum systems.
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| 8. |
- Hort, O., et al.
(författare)
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High-flux source of coherent XUV pulses for user applications
- 2019
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 27:6, s. 8871-8883
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental results obtained at a user-oriented XUV beamline implemented at the ELI Beamlines facility. The coherent XUV radiation is produced via high harmonic generation in gases in a loose focusing geometry. The heamline is designed to be driven by 1 kHz, 100 mJ, 20 Is pulses centered at a wavelength of 830 nm. Results such as XUV spectra, beam wavefront and pulse energy obtained during the heamline commissioning with a commercial 1 kHz, 5 mJ, 40 fs laser system are presented. A unique XUV spectrometer for source characterization designed to reach a very high sensitivity is described in detail, and we demonstrate a novel technique for single shot and every shot. XUV pulse energy measurement. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
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| 9. |
- Kivimäki, A., et al.
(författare)
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The multielectron character of the S 2p → 4eg shape resonance in the SF6 molecule studied via detection of soft X-ray emission and neutral high-Rydberg fragments
- 2016
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 209, s. 26-33
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the nature of the S 2p → 4eg shape resonance in the SF6 molecule by performing two different experiments. Soft X-ray emission spectra measured at the 4eg shape resonance reveal features that do not originate from the S 2p-1 states. One of the features can be assigned to the 6a1g → S 2p transition. The 6a1g orbital, which is empty in the molecular ground state, can be populated either in core-valence double excitations or in S 2p shake-up transitions. Both these channels are considered. We have also studied the fragmentation of SF6 molecule after the decay of the S 2p core-hole states by observing neutral fragments in high-Rydberg states, where an electron occupies an orbital with n ≥ 20 (n is the principal quantum number). Such neutral fragments become, in relative terms, more abundant at the S 2p → 4eg shape resonance with respect to the S 2p → 2t2g shape resonance, which is a pure one-electron phenomenon.
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| 10. |
- Kühn, Sergei, et al.
(författare)
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The ELI-ALPS facility : The next generation of attosecond sources
- 2017
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 50:13
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Forskningsöversikt (refereegranskat)abstract
- This review presents the technological infrastructure that will be available at the Extreme Light Infrastructure Attosecond Light Pulse Source (ELI-ALPS) international facility. ELI-ALPS will offer to the international scientific community ultrashort pulses in the femtosecond and attosecond domain for time-resolved investigations with unprecedented levels of high quality characteristics. The laser sources and the attosecond beamlines available at the facility will make attosecond technology accessible for scientists lacking access to these novel tools. Time-resolved investigation of systems of increasing complexity is envisaged using the end stations that will be provided at the facility.
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