scholarly journals Single-pulse phase-contrast imaging at free-electron lasers in the hard X-ray regime

2021 ◽  
Vol 28 (1) ◽  
pp. 52-63
Author(s):  
Johannes Hagemann ◽  
Malte Vassholz ◽  
Hannes Hoeppe ◽  
Markus Osterhoff ◽  
Juan M. Rosselló ◽  
...  
Keyword(s):  
Free Electron ◽  
Near Field ◽  
Principal Component ◽  
X Rays ◽  
Free Electron Lasers ◽  
Contrast Imaging ◽  
Optical Pump ◽  
Time Resolved ◽  
Full Field ◽  
X Ray

X-ray free-electron lasers (XFELs) have opened up unprecedented opportunities for time-resolved nano-scale imaging with X-rays. Near-field propagation-based imaging, and in particular near-field holography (NFH) in its high-resolution implementation in cone-beam geometry, can offer full-field views of a specimen's dynamics captured by single XFEL pulses. To exploit this capability, for example in optical-pump/X-ray-probe imaging schemes, the stochastic nature of the self-amplified spontaneous emission pulses, i.e. the dynamics of the beam itself, presents a major challenge. In this work, a concept is presented to address the fluctuating illumination wavefronts by sampling the configuration space of SASE pulses before an actual recording, followed by a principal component analysis. This scheme is implemented at the MID (Materials Imaging and Dynamics) instrument of the European XFEL and time-resolved NFH is performed using aberration-corrected nano-focusing compound refractive lenses. Specifically, the dynamics of a micro-fluidic water-jet, which is commonly used as sample delivery system at XFELs, is imaged. The jet exhibits rich dynamics of droplet formation in the break-up regime. Moreover, pump–probe imaging is demonstrated using an infrared pulsed laser to induce cavitation and explosion of the jet.

scholarly journals Time-Resolved Macromolecular Crystallography at Pulsed X-ray Sources

2019 ◽  
Vol 20 (6) ◽  
pp. 1401 ◽  
Author(s):  
Marius Schmidt
Keyword(s):  
Structural Biology ◽  
Free Electron ◽  
Reaction Dynamics ◽  
X Rays ◽  
Free Electron Lasers ◽  
Macromolecular Crystallography ◽  
Time Resolved ◽  
X Ray ◽  
Methodological Aspects

The focus of structural biology is shifting from the determination of static structures to the investigation of dynamical aspects of macromolecular function. With time-resolved macromolecular crystallography (TRX), intermediates that form and decay during the macromolecular reaction can be investigated, as well as their reaction dynamics. Time-resolved crystallographic methods were initially developed at synchrotrons. However, about a decade ago, extremely brilliant, femtosecond-pulsed X-ray sources, the free electron lasers for hard X-rays, became available to a wider community. TRX is now possible with femtosecond temporal resolution. This review provides an overview of methodological aspects of TRX, and at the same time, aims to outline the frontiers of this method at modern pulsed X-ray sources.

scholarly journals Direct protein crystallization on ultrathin membranes for diffraction measurements at X-ray free-electron lasers

2017 ◽  
Vol 50 (3) ◽  
pp. 909-918 ◽  
Author(s):  
Nadia Opara ◽  
Isabelle Martiel ◽  
Stefan A. Arnold ◽  
Thomas Braun ◽  
Henning Stahlberg ◽  
...  
Keyword(s):  
Free Electron ◽  
Protein Crystallization ◽  
Protein Crystallography ◽  
Liquid Jets ◽  
X Rays ◽  
Free Electron Lasers ◽  
Time Resolved ◽  
X Ray ◽  
Drop On Demand ◽  
Novel Approach

A new era of protein crystallography started when X-ray free-electron lasers (XFELs) came into operation, as these provide an intense source of X-rays that facilitates data collection in the `diffract-before-destroy' regime. In typical experiments, crystals sequentially delivered to the beam are exposed to X-rays and destroyed. Therefore, the novel approach of serial crystallography requires thousands of nearly identical samples. Currently applied sample-delivery methods, in particular liquid jets or drop-on-demand systems, suffer from significant sample consumption of the precious crystalline material. Direct protein microcrystal growth by the vapour diffusion technique inside arrays of nanolitre-sized wells is a method specifically tailored to crystallography at XFELs. The wells, with X-ray transparent Si3N4windows as bottoms, are fabricated in silicon chips. Their reduced dimensions can significantly decrease protein specimen consumption. Arrays provide crystalline samples positioned in an ordered way without the need to handle fragile crystals. The nucleation process inside these microfabricated cavities was optimized to provide high membrane coverage and a quasi-random crystal distribution. Tight sealing of the chips and protection of the crystals from dehydration were achieved, as confirmed by diffraction experiments at a protein crystallography beamline. Finally, the test samples were shown to be suitable for time-resolved measurements at an XFEL at femtosecond resolution.

scholarly journals X-Ray Free-Electron Lasers for the Structure and Dynamics of Macromolecules

2019 ◽  
Vol 88 (1) ◽  
pp. 35-58 ◽  
Author(s):  
Henry N. Chapman
Keyword(s):  
Free Electron ◽  
Conformational Dynamics ◽  
Cryogenic Cooling ◽  
X Rays ◽  
Free Electron Lasers ◽  
X Ray ◽  
Virus Particles ◽  
Structure And Dynamics ◽  
Small Crystals ◽  
Serial Crystallography

X-ray free-electron lasers provide femtosecond-duration pulses of hard X-rays with a peak brightness approximately one billion times greater than is available at synchrotron radiation facilities. One motivation for the development of such X-ray sources was the proposal to obtain structures of macromolecules, macromolecular complexes, and virus particles, without the need for crystallization, through diffraction measurements of single noncrystalline objects. Initial explorations of this idea and of outrunning radiation damage with femtosecond pulses led to the development of serial crystallography and the ability to obtain high-resolution structures of small crystals without the need for cryogenic cooling. This technique allows the understanding of conformational dynamics and enzymatics and the resolution of intermediate states in reactions over timescales of 100 fs to minutes. The promise of more photons per atom recorded in a diffraction pattern than electrons per atom contributing to an electron micrograph may enable diffraction measurements of single molecules, although challenges remain.

Accelerator-based X-ray sources: synchrotron radiation, X-ray free electron lasers and beyond

2019 ◽  
Vol 377 (2147) ◽  
pp. 20180231 ◽  
Author(s):  
Tetsuya Ishikawa
Keyword(s):  
Synchrotron Radiation ◽  
Storage Ring ◽  
Free Electron ◽  
Continuous Wave ◽  
Transitional Period ◽  
Light Sources ◽  
X Rays ◽  
Free Electron Lasers ◽  
Beam Emittance ◽  
X Ray

The evolution of synchrotron radiation (SR) sources and related sciences is discussed to explain the ‘generation’ of the SR sources. Most of the contemporary SR sources belong to the third generation, where the storage rings are optimized for the use of undulator radiation. The undulator development allowed to reduction of the electron energy of the storage ring necessary for delivering 10 keV X-rays from the initial 6–8 GeV to the current 3 Gev. Now is the transitional period from the double-bend-achromat lattice-based storage ring to the multi-bend-achromat lattice to achieve much smaller electron beam emittance. Free electron lasers are the other important accelerator-based light sources which recently reached hard X-ray regime by using self-amplified spontaneous emission scheme. Future accelerator-based X-ray sources should be continuous wave X-ray free electron lasers and pulsed X-ray free electron lasers. Some pathways to reach the future case are discussed. This article is part of the theme issue ‘Fifty years of synchrotron science: achievements and opportunities’.

scholarly journals All Femtosecond Optical Pump and X-Ray Probe: Holey-Axicon for Free Electron Laser

2020 ◽  
Author(s):  
Vijayakumar Anand ◽  
Jovan Maksimovic ◽  
Tomas Katkus ◽  
Soon Hock Ng ◽  
Orestas Ulcinas ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Optical Axis ◽  
Bessel Beam ◽  
X Rays ◽  
Temporal Dimension ◽  
Optical Elements ◽  
Optical Pump ◽  
X Ray ◽  
Fs Laser

We put forward a co-axial pump(optical)-probe(X-rays) experimental concept and show performance of the optical component. A Bessel beam generator with a central 100 micrometers-diameter hole (on the optical axis) was fabricated using femtosecond (fs) laser structuring inside a silica plate. This flat-axicon optical element produces a needle-like axial intensity distribution which can be used for the optical pump pulse. The fs-X-ray free electron laser (X-FEL) beam of sub-1 micrometer diameter can be introduced through the central hole along the optical axis onto a target as a probe. Different realisations of optical pump are discussed. Such optical elements facilitate alignment of ultra-short fs-pulses in space and time and can be used in light-matter interaction experiments at extreme energy densities on the surface and in the volume of targets. Full advantage of ultra-short 10 fs X-FEL probe pulses with fs-pump(optical) opens an unexplored temporal dimension of phase transitions and the fastest laser-induced rates of material heating and quenching. A wider field of applications of fs-laser-enabled structuring of materials and design of specific optical elements for astrophotonics is presented.

On-line monitoring of the spatial properties of hard X-ray free-electron lasers based on a grating splitter

2019 ◽  
Vol 26 (3) ◽  
pp. 619-628 ◽  
Author(s):  
Wenqiang Hua ◽  
Guangzhao Zhou ◽  
Zhe Hu ◽  
Shumin Yang ◽  
Keliang Liao ◽  
...  
Keyword(s):  
Free Electron ◽  
Incident Beam ◽  
Single Pulse ◽  
X Rays ◽  
Free Electron Lasers ◽  
Spatial Characteristics ◽  
X Ray ◽  
First Order ◽  
Spatial Properties ◽  
On Line

X-ray free-electron lasers (XFELs) play an increasingly important role in addressing the new scientific challenges relating to their high brightness, high coherence and femtosecond time structure. As a result of pulse-by-pulse fluctuations, the pulses of an XFEL beam may demonstrate subtle differences in intensity, energy spectrum, coherence, wavefront, etc., and thus on-line monitoring and diagnosis of a single pulse are required for many XFEL experiments. Here a new method is presented, based on a grating splitter and bending-crystal analyser, for single-pulse on-line monitoring of the spatial characteristics including the intensity profile, coherence and wavefront, which was suggested and applied experimentally to the temporal diagnosis of an XFEL single pulse. This simulation testifies that the intensity distribution, coherence and wavefront of the first-order diffracted beam of a grating preserve the properties of the incident beam, by using the coherent mode decomposition of the Gaussian–Schell model and Fourier optics. Indicatively, the first-order diffraction of appropriate gratings can be used as an alternative for on-line monitoring of the spatial properties of a single pulse without any characteristic deformation of the principal diffracted beam. However, an interesting simulation result suggests that the surface roughness of gratings will degrade the spatial characteristics in the case of a partially coherent incident beam. So, there exists a suitable roughness value for non-destructive monitoring of the spatial properties of the downstream beam, which depends on the specific optical path. Here, experiments based on synchrotron radiation X-rays are carried out in order to verify this method in principle. The experimental results are consistent with the theoretical calculations.

scholarly journals Phase-Contrast and Dark-Field Imaging

2018 ◽  
Vol 4 (10) ◽  
pp. 113
Author(s):  
Simon Zabler
Keyword(s):  
Phase Contrast ◽  
Dark Field ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
Contrast Imaging ◽  
Full Field ◽  
X Ray ◽  
Dark Field Imaging ◽  
Contrast Mechanisms ◽  
Field Imaging

Very early, in 1896, Wilhelm Conrad Röntgen, the founding father of X-rays, attempted to measure diffraction and refraction by this new kind of radiation, in vain. Only 70 years later, these effects were measured by Ulrich Bonse and Michael Hart who used them to make full-field images of biological specimen, coining the term phase-contrast imaging. Yet, another 30 years passed until the Talbot effect was rediscovered for X-radiation, giving rise to a micrograting based interferometer, replacing the Bonse–Hart interferometer, which relied on a set of four Laue-crystals for beam splitting and interference. By merging the Lau-interferometer with this Talbot-interferometer, another ten years later, measuring X-ray refraction and X-ray scattering full-field and in cm-sized objects (as Röntgen had attempted 110 years earlier) became feasible in every X-ray laboratory around the world. Today, now that another twelve years have passed and we are approaching the 125th jubilee of Röntgen’s discovery, neither Laue-crystals nor microgratings are a necessity for sensing refraction and scattering by X-rays. Cardboard, steel wool, and sandpaper are sufficient for extracting these contrasts from transmission images, using the latest image reconstruction algorithms. This advancement and the ever rising number of applications for phase-contrast and dark-field imaging prove to what degree our understanding of imaging physics as well as signal processing have advanced since the advent of X-ray physics, in particular during the past two decades. The discovery of the electron, as well as the development of electron imaging technology, has accompanied X-ray physics closely along its path, both modalities exploring the applications of new dark-field contrast mechanisms these days. Materials science, life science, archeology, non-destructive testing, and medicine are the key faculties which have already integrated these new imaging devices, using their contrast mechanisms in full. This special issue “Phase-Contrast and Dark-field Imaging” gives us a broad yet very to-the-point glimpse of research and development which are currently taking place in this very active field. We find reviews, applications reports, and methodological papers of very high quality from various groups, most of which operate X-ray scanners which comprise these new imaging modalities.

scholarly journals Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies

2019 ◽  
Vol 9 (24) ◽  
pp. 5505 ◽  
Author(s):  
Eriko Nango ◽  
Minoru Kubo ◽  
Kensuke Tono ◽  
So Iwata
Keyword(s):  
Data Collection ◽  
Free Electron ◽  
Free Electron Laser ◽  
Current Status ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray ◽  
Collection Strategies ◽  
Serial Femtosecond Crystallography

Structural information on protein dynamics is a critical factor in fully understanding the protein functions. Pump-probe time-resolved serial femtosecond crystallography (TR-SFX) is a recently established technique for visualizing the structural changes or reactions in proteins that are at work with high spatial and temporal resolution. In the pump-probe method, protein microcrystals are continuously delivered from an injector and exposed to an X-ray free-electron laser (XFEL) pulse after a trigger to initiate a reaction, such as light, chemicals, temperature, and electric field, which affords the structural snapshots of intermediates that occur in the protein. We are in the process of developing the device and techniques for pump-probe TR-SFX while using XFEL produced at SPring-8 Angstrom Compact Free-Electron Laser (SACLA). In this paper, we described our current development details and data collection strategies for the optical pump X-ray probe TR-SFX experiment at SACLA and then reported the techniques of in crystallo TR spectroscopy, which is useful in clarifying the nature of reaction that takes place in crystals in advance.

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