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| 2. |
- Jo, W., et al.
(författare)
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Nanosecond X-ray photon correlation spectroscopy using pulse time structure of a storage-ring source
- 2021
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Ingår i: IUCrJ. - : International Union of Crystallography. - 2052-2525. ; 8, s. 124-130
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Tidskriftsartikel (refereegranskat)abstract
- X-ray photon correlation spectroscopy (XPCS) is a routine technique to study slow dynamics in complex systems at storage-ring sources. Achieving nanosecond time resolution with the conventional XPCS technique is, however, still an experimentally challenging task requiring fast detectors and sufficient photon flux. Here, the result of a nanosecond XPCS study of fast colloidal dynamics is shown by employing an adaptive gain integrating pixel detector (AGIPD) operated at frame rates of the intrinsic pulse structure of the storage ring. Correlation functions from single-pulse speckle patterns with the shortest correlation time of 192 ns have been calculated. These studies provide an important step towards routine fast XPCS studies at storage rings. © 2021.
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| 3. |
- Becker, J., et al.
(författare)
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Performance tests of an AGIPD 0.4 assembly at the beamline P10 of PETRA III
- 2013
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 8:6, s. Art. no. P06007-
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Tidskriftsartikel (refereegranskat)abstract
- The Adaptive Gain Integrating Pixel Detector (AGIPD) is a novel detector system, currently under development by a collaboration of DESY, the Paul Scherrer Institute in Switzerland, the University of Hamburg and the University of Bonn, and is primarily designed for use at the European XFEL. To verify key features of this detector, an AGIPD 0.4 test chip assembly was tested at the P10 beamline of the PETRA III synchrotron at DESY. The test chip successfully imaged both the direct synchrotron beam and single 7.05 keV photons at the same time, demonstrating the large dynamic range required for XFEL experiments. X-ray scattering measurements from a test sample agree with standard measurements and show the chip's capability of observing dynamics at the microsecond time scale.
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| 4. |
- Moron, M., et al.
(författare)
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Gelation Dynamics upon Pressure-Induced Liquid-Liquid Phase Separation in a Water-Lysozyme Solution
- 2022
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 126:22, s. 4160-4167
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Tidskriftsartikel (refereegranskat)abstract
- Employing X-ray photon correlation spectroscopy, we measure the kinetics and dynamics of a pressure-induced liquid–liquid phase separation (LLPS) in a water–lysozyme solution. Scattering invariants and kinetic information provide evidence that the system reaches the phase boundary upon pressure-induced LLPS with no sign of arrest. The coarsening slows down with increasing quench depths. The g2 functions display a two-step decay with a gradually increasing nonergodicity parameter typical for gelation. We observe fast superdiffusive (γ ≥ 3/2) and slow subdiffusive (γ < 0.6) motion associated with fast viscoelastic fluctuations of the network and a slow viscous coarsening process, respectively. The dynamics age linearly with time τ ∝ tw, and we observe the onset of viscoelastic relaxation for deeper quenches. Our results suggest that the protein solution gels upon reaching the phase boundary.
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| 5. |
- Shen, L., et al.
(författare)
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Interplay between relaxational atomic fluctuations and charge density waves in La2-xSrxCuO4
- 2023
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Ingår i: Physical Review B. - 2469-9950. ; 108:20
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Tidskriftsartikel (refereegranskat)abstract
- In the cuprate superconductors, the spatial coherence of the charge density wave (CDW) state grows below a temperature TCDW, the origin of which is debated. Using x-ray photon correlation spectroscopy, we have studied the temporal atomic relaxation dynamics in La1.88Sr0.12CuO4 to shed light on this question. Cooling within an emergent structurally distorted phase, which favors the CDW modulation in symmetry and develops in two stages between 180 and 120 K, we observe a crossover from cooperativelike to incoherentlike relaxation dynamics at TCDW=75(10) K. We argue that, if the CDW is hosted by this distortion, the concomitant relaxational crossover and enhancement of CDW spatial coherence supports the interplay between relaxational atomic fluctuations and CDWs in materials of this class on quasistatic times cales.
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| 6. |
- Westermeier, F., et al.
(författare)
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Connecting structure, dynamics and viscosity in sheared soft colloidal liquids : A medley of anisotropic fluctuations
- 2015
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 12:1, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- Structural distortion and relaxation are central to any liquid flow. Their full understanding requires simultaneous probing of the mechanical as well as structural and dynamical response. We provide the first full dynamical measurement of the transient structure using combined coherent X-ray scattering and rheology on electrostatically interacting colloidal fluids. We find a stress overshoot during the start-up of shear which is due to the strong anisotropic overstretching and compression of nearest-neighbor distances. The rheological response is reflected in uncorrelated entropy-driven intensity fluctuations. While the structural distortion under steady shear is well described by Smoluchowski theory, we find an increase of the particle dynamics beyond the trivial contribution of flow. After the cessation of shear, the full fluid microstructure and dynamics are restored, both on the structural relaxation timescale. We thus find unique structure-dynamics relations in liquid flow, responsible for the macroscopic rheological behavior of the system. © The Royal Society of Chemistry.
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