Publications by authors named "Thomas Tschentscher"

9 Publications

  • Page 1 of 1

Evidence of shock-compressed stishovite above 300 GPa.

Sci Rep 2020 Jun 23;10(1):10197. Epub 2020 Jun 23.

European XFEL, Schenefeld, 22869, Germany.

SiO is one of the most fundamental constituents in planetary bodies, being an essential building block of major mineral phases in the crust and mantle of terrestrial planets (1-10 M). Silica at depths greater than 300 km may be present in the form of the rutile-type, high pressure polymorph stishovite (P4/mnm) and its thermodynamic stability is of great interest for understanding the seismic and dynamic structure of planetary interiors. Previous studies on stishovite via static and dynamic (shock) compression techniques are contradictory and the observed differences in the lattice-level response is still not clearly understood. Here, laser-induced shock compression experiments at the LCLS- and SACLA XFEL light-sources elucidate the high-pressure behavior of stishovite on the lattice-level under in situ conditions on the Hugoniot to pressures above 300 GPa. We find stishovite is still (meta-)stable at these conditions, and does not undergo any phase transitions. This contradicts static experiments showing structural transformations to the CaCl, α-PbO and pyrite-type structures. However, rate-limited kinetic hindrance may explain our observations. These results are important to our understanding into the validity of EOS data from nanosecond experiments for geophysical applications.
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http://dx.doi.org/10.1038/s41598-020-66340-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311448PMC
June 2020

Foreword to the special virtual issue on X-ray free-electron lasers.

J Synchrotron Radiat 2020 May 1;27(Pt 3):576. Epub 2020 May 1.

RIKEN SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148, Japan.

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http://dx.doi.org/10.1107/S1600577520002799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285675PMC
May 2020

Resolving dynamic fragmentation of liquids at the nanoscale with ultrafast small-angle X-ray scattering.

J Synchrotron Radiat 2019 Sep 1;26(Pt 5):1412-1421. Epub 2019 Aug 1.

The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China.

High-brightness coherent ultrashort X-ray free-electron lasers (XFELs) are promising in resolving nanoscale structures at the highest temporal resolution (∼10 fs). The feasibility is explored of resolving ultrafast fragmentation of liquids at the nanoscale with single-shot small-angle X-ray scattering (SAXS) on the basis of large-scale molecular dynamics simulations. Fragmentation of liquid sheets under adiabatic expansion is investigated. From the simulated SAXS patterns, particle-volume size distributions are obtained with the regularization method and average particle sizes with the weighted Guinier method, at different expansion rates. The particle sizes obtained from simulated SAXS are in excellent agreement with direct cluster analysis. Pulse-width effects on SAXS measurements are examined. The results demonstrate the feasibility of resolving the nanoscale dynamics of fragmentation and similar processes with SAXS, and provide guidance for future XFEL experiments and data interpretation.
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http://dx.doi.org/10.1107/S160057751900732XDOI Listing
September 2019

The Single Particles, Clusters and Biomolecules and Serial Femtosecond Crystallography instrument of the European XFEL: initial installation.

J Synchrotron Radiat 2019 May 12;26(Pt 3):660-676. Epub 2019 Apr 12.

European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.

The European X-ray Free-Electron Laser (FEL) became the first operational high-repetition-rate hard X-ray FEL with first lasing in May 2017. Biological structure determination has already benefitted from the unique properties and capabilities of X-ray FELs, predominantly through the development and application of serial crystallography. The possibility of now performing such experiments at data rates more than an order of magnitude greater than previous X-ray FELs enables not only a higher rate of discovery but also new classes of experiments previously not feasible at lower data rates. One example is time-resolved experiments requiring a higher number of time steps for interpretation, or structure determination from samples with low hit rates in conventional X-ray FEL serial crystallography. Following first lasing at the European XFEL, initial commissioning and operation occurred at two scientific instruments, one of which is the Single Particles, Clusters and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument. This instrument provides a photon energy range, focal spot sizes and diagnostic tools necessary for structure determination of biological specimens. The instrumentation explicitly addresses serial crystallography and the developing single particle imaging method as well as other forward-scattering and diffraction techniques. This paper describes the major science cases of SPB/SFX and its initial instrumentation - in particular its optical systems, available sample delivery methods, 2D detectors, supporting optical laser systems and key diagnostic components. The present capabilities of the instrument will be reviewed and a brief outlook of its future capabilities is also described.
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http://dx.doi.org/10.1107/S1600577519003308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510195PMC
May 2019

Start-to-end simulation of single-particle imaging using ultra-short pulses at the European X-ray Free-Electron Laser.

IUCrJ 2017 Sep 1;4(Pt 5):560-568. Epub 2017 Sep 1.

European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany.

Single-particle imaging with X-ray free-electron lasers (XFELs) has the potential to provide structural information at atomic resolution for non-crystalline biomolecules. This potential exists because ultra-short intense pulses can produce interpretable diffraction data notwithstanding radiation damage. This paper explores the impact of pulse duration on the interpretability of diffraction data using comprehensive and realistic simulations of an imaging experiment at the European X-ray Free-Electron Laser. It is found that the optimal pulse duration for molecules with a few thousand atoms at 5 keV lies between 3 and 9 fs.
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http://dx.doi.org/10.1107/S2052252517009496DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5619849PMC
September 2017

A comprehensive simulation framework for imaging single particles and biomolecules at the European X-ray Free-Electron Laser.

Sci Rep 2016 04 25;6:24791. Epub 2016 Apr 25.

European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany.

The advent of newer, brighter, and more coherent X-ray sources, such as X-ray Free-Electron Lasers (XFELs), represents a tremendous growth in the potential to apply coherent X-rays to determine the structure of materials from the micron-scale down to the Angstrom-scale. There is a significant need for a multi-physics simulation framework to perform source-to-detector simulations for a single particle imaging experiment, including (i) the multidimensional simulation of the X-ray source; (ii) simulation of the wave-optics propagation of the coherent XFEL beams; (iii) atomistic modelling of photon-material interactions; (iv) simulation of the time-dependent diffraction process, including incoherent scattering; (v) assembling noisy and incomplete diffraction intensities into a three-dimensional data set using the Expansion-Maximisation-Compression (EMC) algorithm and (vi) phase retrieval to obtain structural information. We demonstrate the framework by simulating a single-particle experiment for a nitrogenase iron protein using parameters of the SPB/SFX instrument of the European XFEL. This exercise demonstrably yields interpretable consequences for structure determination that are crucial yet currently unavailable for experiment design.
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http://dx.doi.org/10.1038/srep24791DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4842992PMC
April 2016

Investigating the interaction of x-ray free electron laser radiation with grating structure.

Opt Lett 2012 Aug;37(15):3033-5

European XFEL GmbH, Hamburg, Germany.

The interaction of free electron laser pulses with grating structure is investigated using 4.6±0.1 nm radiation at the FLASH facility in Hamburg. For fluences above 63.7±8.7 mJ/cm2, the interaction triggers a damage process starting at the edge of the grating structure as evidenced by optical and atomic force microscopy. Simulations based on solution of the Helmholtz equation demonstrate an enhancement of the electric field intensity distribution at the edge of the grating structure. A procedure is finally deduced to evaluate damage threshold.
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http://dx.doi.org/10.1364/OL.37.003033DOI Listing
August 2012

Ultrafast potential energy surface softening of one-dimensional organic conductors revealed by picosecond time-resolved Laue crystallography.

J Phys Chem A 2010 Jul;114(29):7677-81

SLAC, Menlo Park, California 94025, USA.

Time-resolved Laue crystallography has been employed to study the structural dynamics of a one-dimensional organic conductor (tetrathiafulvalene-p-chloranil) during photoexcitation in the regime of the neutral to ionic phase transition. Exciting this crystalline system with 800 nm 100 fs long optical pulses leads to ultrafast population of a structural intermediate as early as 50 ps after excitation with a lifetime of at least 10 ns. Starting from the neutral phase, this intermediate has been assigned as a precursor state toward the photoinduced population of the ionic phase. The observed intensity changes are significantly different from comparable equilibrium structures. The interpretation of this structural data is that the potential of this intermediate is being softened during its population in a dynamical process. The depopulation proceeds through thermal processes.
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http://dx.doi.org/10.1021/jp104081bDOI Listing
July 2010

Subnanometer-scale measurements of the interaction of ultrafast soft x-ray free-electron-laser pulses with matter.

Phys Rev Lett 2007 Apr 4;98(14):145502. Epub 2007 Apr 4.

Lawrence Livermore National Laboratory, Livermore, California 94550, USA.

At the recently built FLASH x-ray free-electron laser, we studied the reflectivity of Si/C multilayers with fluxes up to 3 x 10(14) W/cm2. Even though the nanostructures were ultimately completely destroyed, we found that they maintained their integrity and reflectance characteristics during the 25-fs-long pulse, with no evidence for any structural changes over lengths greater than 3 A. This experiment demonstrates that with intense ultrafast pulses, structural damage does not occur during the pulse, giving credence to the concept of diffraction imaging of single macromolecules.
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http://dx.doi.org/10.1103/PhysRevLett.98.145502DOI Listing
April 2007