| 1. |
- Bengtsson, Å U J, et al.
(författare)
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Repetitive non-thermal melting as a timing monitor for femtosecond pump/probe X-ray experiments
- 2020
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 7:5, s. 054303-054303
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved optical pump/X-ray probe experiments are often used to study structural dynamics. To ensure high temporal resolution, it is necessary to monitor the timing between the X-ray pulses and the laser pulses. The transition from a crystalline solid material to a disordered state in a non-thermal melting process can be used as a reliable timing monitor. We have performed a study of the non-thermal melting of InSb in single-shot mode, where we varied the sample temperature in order to determine the conditions required for repetitive melting. We show how experimental conditions affect the feasibility of such a timing tool.
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| 2. |
- Enquist, Henrik, et al.
(författare)
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FemtoMAX - An X-ray beamline for structural dynamics at the short-pulse facility of MAX IV
- 2018
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 25:2, s. 570-579
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Tidskriftsartikel (refereegranskat)abstract
- The FemtoMAX beamline facilitates studies of the structural dynamics of materials. Such studies are of fundamental importance for key scientific problems related to programming materials using light, enabling new storage media and new manufacturing techniques, obtaining sustainable energy by mimicking photosynthesis, and gleaning insights into chemical and biological functional dynamics. The FemtoMAX beamline utilizes the MAX IV linear accelerator as an electron source. The photon bursts have a pulse length of 100fs, which is on the timescale of molecular vibrations, and have wavelengths matching interatomic distances (Å). The uniqueness of the beamline has called for special beamline components. This paper presents the beamline design including ultrasensitive X-ray beam-position monitors based on thin Ce:YAG screens, efficient harmonic separators and novel timing tools.The FemtoMAX beamline facilitates studies of the structural dynamics of materials on the femtosecond timescale. The first commissioning results are presented.
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| 3. |
- Jarnac, A., et al.
(författare)
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Communication : Demonstration of a 20 ps X-ray switch based on a photoacoustic transducer
- 2017
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 4:5
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Tidskriftsartikel (refereegranskat)abstract
- We have studied an X-ray switch based on a gold coated indium antimonide crystal using time-resolved X-ray diffraction and demonstrated that the switch could reduce the pulse duration of a 100 ps X-ray pulse down to 20 ps with a peak reflectivity of 8%. We have used a dynamical diffraction code to predict the performance of the switch, which was then confirmed experimentally. The experiment was carried out at the FemtoMAX beamline at the short-pulse facility of the MAX IV laboratory. The performance and limitation of the switch are discussed in terms of acoustic transport properties between the two materials and the electron transport properties of gold.
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| 4. |
- Jensen, Maja, 1978, et al.
(författare)
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High-resolution macromolecular crystallography at the FemtoMAX beamline with time-over-threshold photon detection
- 2021
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Ingår i: Journal of Synchrotron Radiation. - 1600-5775 .- 0909-0495. ; 28, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- Protein dynamics contribute to protein function on different time scales. Ultrafast X-ray diffraction snapshots can visualize the location and amplitude of atom displacements after perturbation. Since amplitudes of ultrafast motions are small, high-quality X-ray diffraction data is necessary for detection. Diffraction from bovine trypsin crystals using single femtosecond X-ray pulses was recorded at FemtoMAX, which is a versatile beamline of the MAX IV synchrotron. The time-over-threshold detection made it possible that single photons are distinguishable even under short-pulse low-repetition-rate conditions. The diffraction data quality from FemtoMAX beamline enables atomic resolution investigation of protein structures. This evaluation is based on the shape of the Wilson plot, cumulative intensity distribution compared with theoretical distribution, I/σ, Rmerge /Rmeas and CC1/2 statistics versus resolution. The FemtoMAX beamline provides an interesting alternative to X-ray free-electron lasers when studying reversible processes in protein crystals.
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| 5. |
- Wang, Xiaocui, et al.
(författare)
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Generation of a large compressive strain wave in graphite by ultrashort-pulse laser irradiation
- 2019
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- We have studied strain wave generation in graphite induced by an intense ultrashort laser pulse. The study was performed in the intensity regime above the ablation threshold of graphite. The aim was to maximize the strain and, thus, also the internal pressure (stress). Laser pulses with a 1 ps temporal duration melt the surface of graphite resulting in a molten material which initially exists at the solid density. As the molten material expands, a compressive strain wave starts propagating into the crystal below the molten layer. The strain pulse was studied with time-resolved X-ray diffraction. At a temporal delay of 100 ps after laser excitation, we observed >10% compressive strain, which corresponds to a pressure of 7.2 GPa. This strain could be reproduced by hydrodynamic simulations, which also provided a temperature map as a function of time and depth.
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| 6. |
- Wang, Xiaocui, et al.
(författare)
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Role of Thermal Equilibrium Dynamics in Atomic Motion during Nonthermal Laser-Induced Melting
- 2020
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Ingår i: Physical Review Letters. - 1079-7114. ; 124:10
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Tidskriftsartikel (refereegranskat)abstract
- This study shows that initial atomic velocities as given by thermodynamics play an important role in the dynamics of phase transitions. We tracked the atomic motion during nonthermal laser-induced melting of InSb at different initial temperatures. The ultrafast atomic motion following bond breaking can in general be governed by two mechanisms: the random velocity of each atom at the time of bond breaking (inertial model), and the forces acting on the atoms after bond breaking. The melting dynamics was found to follow the inertial model over a wide temperature range.
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