The local and average structure of Ba(Ti, Ce)O3 perovskite solid solution: effect of cerium concentration and particle size
The amazing properties of ferroelectric perovskite BaTiO3 (BT) and its solid solutions make them indispensable for many technological applications (e.g. multilayer capacitors). Unfortunately, the so-called `size effect' limits their use. Indeed, under a certain critical particle size, these materials show a suppression of the spontaneous polarization and thus of the ferroelectric properties. In pure nanometric BaTiO3, this is related to a certain local structural disorder. However, only a few studies have explored BT solid solutions, where the doping effect, coupled to the reduced particle size, can play an important role....
Source: Journal of Synchrotron Radiation - June 6, 2019 Category: Physics Authors: Confalonieri, G. Buscaglia, V. Canu, G. Buscaglia, M.T. Dapiaggi, M. Tags: perovskite size effect Pair Distribution Function research papers Source Type: research

Diffraction properties of a strongly bent diamond crystal used as a dispersive spectrometer for XFEL pulses
Self-amplified spontaneous emission (SASE) enables X-ray free-electron lasers (XFELs) to generate hard X-ray pulses of sub-100   fs duration. However, due to the stochastic nature of SASE, the energy spectrum fluctuates from pulse to pulse. Many experiments that employ XFEL radiation require the resolution of the spectrum of each pulse. The work presented here investigates the capacity of a thin strongly bent diamond crystal to resolve the energy spectra of hard X-ray SASE pulses by studying its diffraction properties. Rocking curves of the symmetric C*(440) reflection have been measured for different bending radii. T...
Source: Journal of Synchrotron Radiation - June 6, 2019 Category: Physics Authors: Samoylova, L. Boesenberg, U. Chumakov, A. Kaganer, V. Petrov, I. Roth, T. R ü ffer, R. Sinn, H. Terentyev, S. Madsen, A. Tags: XFELs free-electron lasers in-line spectrometers dynamical diffraction strongly bent thin diamond crystals bent diamond crystals SASE XFEL spectrometers research papers Source Type: research

Minimizing experimental artefacts in synchrotron-based X-ray analyses of Fe speciation in tissues of rice plants
Iron (Fe) plays an important role within environmental systems. Synchrotron-based X-ray approaches, including X-ray absorption spectroscopy (XAS), provide powerful tools for in situ analyses of Fe speciation, but beam damage during analysis may alter Fe speciation during its measurement. XAS was used to examine whether experimental conditions affect the analysis of Fe speciation in plant tissues. Even when analyzed in a cryostat at 12   K, it was found that FeIII can rapidly (within 0.5 – 1   min) photoreduce to FeII, although the magnitude of photoreduction varied depending upon the hydration of the sample, the ...
Source: Journal of Synchrotron Radiation - June 6, 2019 Category: Physics Authors: Wang, P. McKenna, B.A. Menzies, N.W. Li, C. Glover, C.J. Zhao, F.-J. Kopittke, P.M. Tags: X-ray absorption spectroscopy iron speciation photoreduction beam damage cryostats freeze drying plant-root tissues research papers Source Type: research

The XFP (17-BM) beamline for X-ray footprinting at NSLS-II
Hydroxyl-radical mediated synchrotron X-ray footprinting (XF) is a powerful solution-state technique in structural biology for the study of macromolecular structure and dynamics of proteins and nucleic acids, with several synchrotron resources available to serve the XF community worldwide. The XFP (Biological X-ray Footprinting) beamline at the NSLS-II was constructed on a three-pole wiggler source at 17-BM to serve as the premier beamline for performing this technique, providing an unparalleled combination of high flux density broadband beam, flexibility in beam morphology, and sample handling capabilities specifically de...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Asuru, A. Farquhar, E.R. Sullivan, M. Abel, D. Toomey, J. Chance, M.R. Bohon, J. Tags: footprinting structural dynamics beamline solution state beamlines Source Type: research

Towards an extremely high resolution broad-band flat-field spectrometer in the `water window'
The optical design of a novel spectrometer is presented, combining a cylindrically convex pre-mirror with a cylindrically concave varied-line-spacing grating (both in the meridional) to deliver a resolving power of 100000 – 200000 in the `water window' (2 – 5   nm). Most remarkably, the extremely high spectral resolution is achieved for an effective meridional source size of 50   µ m (r.m.s.); this property could potentially be applied to diagnose SASE-FEL and well resolve individual single spikes in its radiation spectrum. The overall optical aberrations of the system are well analysed and compensate...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Li, Z. Li, B. Tags: spectrometer X-ray optics resolution enhancement geometric optics ray tracing diffraction principle optical aberration analysis and optimization research papers Source Type: research

High-pressure and -temperature spinning capillary cell for in situ synchrotron X-ray powder diffraction
In situ research of materials under moderate pressures (hundreds of bar) is essential in many scientific fields. These range from gas sorption to chemical and biological processes. One industrially important discipline is the hydration of oil well cements. Existing capillary cells in this pressure range are static as they are easy to design and operate. This is convenient for the study of single-phase materials; however, powder diffraction quantitative analyses for multiphase systems cannot be performed accurately as a good powder average cannot be attained. Here, the design, construction and commissioning of a cost-effect...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Fraga, E. Zea-Garcia, J.D. Y á ñ ez, A. De la Torre, A.G. Cuesta, A. Valc á rcel-Fern á ndez, R. Farr é -Par í s, F. Malfois, M. Aranda, M.A.G. Tags: high-pressure equipment oil well cement cement hydration Rietveld quantitative phase analysis research papers Source Type: research

A variable fixed-focus constant optimization method for a variable-included-angle varied-line-spacing plane-grating monochromator
Variable-included-angle varied-line-spacing plane-grating monochromators (VIA-VPGM) have been applied to many beamlines because of the self-focusing and aberration-correction function of the varied-line-spacing grating. Unfortunately, to optimize the variable-line-spacing coefficient of the grating, the fixed-focus constant (Cff) has to be fixed first in the VIA-VPGM. In this way, some of the advantages of these monochromators are lost, such as the flexibility of choosing a different energy-resolving power by varying the Cff. In this work, a variable Cff optimization method is introduced for a VIA-VPGM. By adopting this me...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Xue, C. Xue, L. Wu, Y. Wang, Y. Yang, S. Tai, R. Tags: synchrotron radiation variable-included-angle varied-line-spacing plane-grating monochromators VIA-VPGM variable Cff research papers Source Type: research

Compact hard X-ray split-and-delay line for studying ultrafast dynamics at free-electron laser sources
A compact hard X-ray split-and-delay line for studying ultrafast dynamics at free-electron laser sources is presented. The device is capable of splitting a single X-ray pulse into two fractions to introduce time delays from − 5 to 815   ps with femtosecond resolution. The split-and-delay line can operate in a wide and continuous energy range between 7 and 16   keV. Compact dimensions of 60 × 60 × 30   cm with a total weight of about 60   kg make it portable and suitable for direct installation in an experimental hutch. The concept of the device is based on crystal diffraction. The piezo-driven sta...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Rysov, R. Roseker, W. Walther, M. Gr ü bel, G. Tags: X-ray optics delay lines free-electron lasers FELs ultrafast dynamics X-ray photon correlation spectroscopy XPCS pump – probe experiments research papers Source Type: research

Operation of X-ray gas monitors at the European XFEL
X-ray gas monitors (XGMs) are operated at the European XFEL for non-invasive single-shot pulse energy measurements and average beam position monitoring. They are used for tuning and maintaining the self-amplified spontaneous emission (SASE) operation and for sorting single-shot experimental data according to the pulse-resolved energy monitor data. The XGMs were developed at DESY based on the specific requirements for the European XFEL. In total, six XGM units are continuously in operation. Here, the main principle and experimental setup of an XGM are summarized, and the locations of the six XGMs at the facility are shown. ...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Maltezopoulos, T. Dietrich, F. Freund, W. Jastrow, U.F. Koch, A. Laksman, J. Liu, J. Planas, M. Sorokin, A.A. Tiedtke, K. Gr ü nert, J. Tags: free-electron lasers photon diagnostics hard X-rays research papers Source Type: research

On smart optimization of blazed soft X-ray gratings
The first attempts to calculate the diffraction efficiencies of gratings in the soft X-ray range were made on a scalar model. The results were simple analytical equations, that always severely overestimated the performance of real objects. In this respect, computer programs were found to be more successful, which rigorously consider all diffracted and refracted waves. Consequently soft X-ray gratings are presently optimized using these tools, which requires rather extensive calculations for any instrument optimization as general trends are not immediately obvious. Here it will be shown that the results of the rigorous calc...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Jark, W. Tags: diffraction grating soft X-rays diffraction efficiency soft X-ray monochromator research papers Source Type: research

First measurements with the K-monochromator at the European XFEL
Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. The SASE1 and SASE2 undulator systems of the European XFEL consist of 35 segments with variable-gap planar undulators which are initially tuned to precise on-axis magnetic field strengths in a magnetic measurement laboratory to keep an important quality parameter – the K-value variation from segment to segment – below a certain limit (3 × 10 − 4 for 12   keV photon energy). After tunnel installation o...
Source: Journal of Synchrotron Radiation - June 4, 2019 Category: Physics Authors: Freund, W. Fr ö hlich, L. Karabekyan, S. Koch, A. Liu, J. N ö lle, D. Wilgen, J. Gr ü nert, J. Tags: XFEL K-mono undulator adjustment research papers Source Type: research

DeepCentering: fully automated crystal centering using deep learning for macromolecular crystallography
High-throughput protein crystallography using a synchrotron light source is an important method used in drug discovery. Beamline components for automated experiments including automatic sample changers have been utilized to accelerate the measurement of a number of macromolecular crystals. However, unlike cryo-loop centering, crystal centering involving automated crystal detection is a difficult process to automate fully. Here, DeepCentering, a new automated crystal centering system, is presented. DeepCentering works using a convolutional neural network, which is a deep learning operation. This system achieves fully automa...
Source: Journal of Synchrotron Radiation - June 3, 2019 Category: Physics Authors: Ito, S. Ueno, G. Yamamoto, M. Tags: automated crystal centering deep learning fully automated structure determination short communications Source Type: research

Focus characterization of the NanoMAX Kirkpatrick – Baez mirror system
The focusing and coherence properties of the NanoMAX Kirkpatrick – Baez mirror system at the fourth-generation MAX IV synchrotron in Lund have been characterized. The direct measurement of nano-focused X-ray beams is possible by scanning of an X-ray waveguide, serving basically as an ultra-thin slit. In quasi-coherent operation, beam sizes of down to 56   nm (FWHM, horizontal direction) can be achieved. Comparing measured Airy-like fringe patterns with simulations, the degree of coherence | μ | has been quantified as a function of the secondary source aperture (SSA); the coherence is larger than 50% for SSA size...
Source: Journal of Synchrotron Radiation - June 3, 2019 Category: Physics Authors: Osterhoff, M. Robisch, A.-L. Soltau, J. Eckermann, M. Kalbfleisch, S. Carbone, D. Johansson, U. Salditt, T. Tags: nano-focus coherence holography research papers Source Type: research

A zone-plate-based two-color spectrometer for indirect X-ray absorption spectroscopy
X-ray absorption spectroscopy (XAS) is a powerful element-specific technique that allows the study of structural and chemical properties of matter. Often an indirect method is used to access the X-ray absorption (XA). This work demonstrates a new XAS implementation that is based on off-axis transmission Fresnel zone plates to obtain the XA spectrum of La0.6Sr0.4MnO3 by analysis of three emission lines simultaneously at the detector, namely the O 2p – 1s, Mn 3s – 2p and Mn 3d – 2p transitions. This scheme allows the simultaneous measurement of an integrated total fluorescence yield and the partial fluoresc...
Source: Journal of Synchrotron Radiation - May 24, 2019 Category: Physics Authors: D ö ring, F. Risch, M. R ö sner, B. Beye, M. Busse, P. Kubi č ek, K. Glaser, L. Miedema, P.S. Soltau, J. Raiser, D. Guzenko, V.A. Szabadics, L. Kochanneck, L. Baumung, M. Buck, J. Jooss, C. Techert, S. David, C. Tags: two-color X-ray absorption spectroscopy zone plates soft X-rays research papers Source Type: research

Scientific instruments for soft X-ray photon-in/photon-out spectroscopy on the PAL-XFEL
An overview is given of the soft X-ray photon-in/photon-out instruments on the free-electron laser (FEL) beamline at the Pohang Accelerator Laboratory, and selected commissioning results are presented. The FEL beamline provides a photon energy of 270 to 1200   eV, with an energy bandwidth of 0.44%, an energy of 200   µ J per pulse and a pulse width of (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - May 24, 2019 Category: Physics Authors: Park, S.H. Yoon, J. Kim, C. Hwang, C. Kim, D.-H. Lee, S.-H. Kwon, S. Tags: pulsed lasers X-ray absorption spectroscopy resonant inelastic X-ray scattering soft X-rays photon in/photon out instruments research papers Source Type: research

Comprehensive model for X-ray-induced damage in protein crystallography
Acquisition of X-ray crystallographic data is always accompanied by structural degradation owing to the absorption of energy. The application of high-fluency X-ray sources to large biomolecules has increased the importance of finding ways to curtail the onset of X-ray-induced damage. A significant effort has been under way with the aim of identifying strategies for protecting protein structure. A comprehensive model is presented that has the potential to explain, both qualitatively and quantitatively, the structural changes induced in crystalline protein at ∼ 100   K. The first step is to consider the qualitative que...
Source: Journal of Synchrotron Radiation - May 24, 2019 Category: Physics Authors: Close, D.M. Bernhard, W.A. Tags: X-ray radiation damage free-radical radiation chemistry macromolecular crystallography DFT calculations amino-acid side chains research papers Source Type: research

FORTE – a multipurpose high-vacuum diffractometer for tender X-ray diffraction and spectroscopy at the SIRIUS beamline of Synchrotron SOLEIL
A new high-vacuum multipurpose diffractometer (called FORTE from the French acronyms of the project) has recently been installed at the tender/hard X-ray SIRIUS beamline of Synchrotron SOLEIL, France. The geometry chosen allows one to work either in the classical Eulerian four-circle geometry for bulk X-ray diffraction (XRD) or in the z-axis geometry for surface XRD. The diffractometer nicely fits the characteristics of the SIRIUS beamline, optimized to work in the 1.1 – 4.5   keV range, and allows one to perform unprecedented diffraction anomalous fine structure (DAFS) experiments in the tender X-ray region, also ...
Source: Journal of Synchrotron Radiation - May 23, 2019 Category: Physics Authors: Ciatto, G. Aubert, N. Lecroard, M. Engblom, C. Fontaine, P. Dubuisson, J.-M. Abiven, Y.-M. Janolin, P.-E. Kiat, J.-M. Dumont, Y. Berini, B. Fouchet, A. Keller, N. Tags: diffractometers tender X-rays diffraction anomalous fine structure (DAFS) X-ray absorption (XAS) functional oxides beamlines Source Type: research

xcalib: a focal spot calibrator for intense X-ray free-electron laser pulses based on the charge state distributions of light atoms
The xcalib toolkit has been developed to calibrate the beam profile of an X-ray free-electron laser (XFEL) at the focal spot based on the experimental charge state distributions (CSDs) of light atoms. Characterization of the fluence distribution at the focal spot is essential to perform the volume integrations of physical quantities for a quantitative comparison between theoretical and experimental results, especially for fluence-dependent quantities. The use of the CSDs of light atoms is advantageous because CSDs directly reflect experimental conditions at the focal spot, and the properties of light atoms have been well e...
Source: Journal of Synchrotron Radiation - May 23, 2019 Category: Physics Authors: Toyota, K. Jurek, Z. Son, S.-K. Fukuzawa, H. Ueda, K. Berrah, N. Rudek, B. Rolles, D. Rudenko, A. Santra, R. Tags: X-ray free-electron laser XFEL calibration characterization beam profile spatial fluence distribution charge state distribution ab initio calculation first-principles calculation research papers Source Type: research

Temperature-induced molecule assembly effects on the near-edge X-ray absorption fine-structure spectra of Zn-phthalocyanine layers on Si substrates
The molecular arrangement of vacuum thermally deposited polycrystalline Zn-phthalocyanine (ZnPc) layers on Si substrates is investigated using near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy in the proximity of the carbon edge at E0 = 287.33   eV. The data were collected as a function of the deposition substrate temperature TS (30, 90, 150 ° C) and the incidence angle θ (20 ° , 45 ° , 70 ° , 90 ° ) of the synchrotron beam with respect to the sample plane. Each spectrum was analysed by mathematical simulation applying an error function for the carbon edge and a set of Voigt and (a...
Source: Journal of Synchrotron Radiation - May 21, 2019 Category: Physics Authors: Fostiropoulos, K. Mete, T. Li, Z. Lauermann, I. Tags: Zn-phthalocyanine molecular orientation NEXAFS research papers Source Type: research

High-numerical-aperture macroscope optics for time-resolved experiments
A novel high-quality custom-made macroscope optics, dedicated to high-resolution time-resolved X-ray tomographic microscopy at the TOMCAT beamline at the Swiss Light Source (Paul Scherrer Institut, Switzerland), is introduced. The macroscope offers 4 × magnification, has a very high numerical aperture of 0.35 and it is modular and highly flexible. It can be mounted both in a horizontal and vertical configuration, enabling imaging of tall samples close to the scintillator, to avoid edge-enhancement artefacts. The macroscope performance was characterized and compared with two existing in-house imaging setups, one dedic...
Source: Journal of Synchrotron Radiation - May 21, 2019 Category: Physics Authors: B ü hrer, M. Stampanoni, M. Rochet, X. B ü chi, F. Eller, J. Marone, F. Tags: X-ray tomographic microscopy high numerical aperture optics optics characterization image quality research papers Source Type: research

Refurbishment of an Au-coated toroidal mirror by capacitively coupled RF plasma discharge
Deposition of synchrotron-radiation-induced carbon contamination on beamline optics causes their performance to deteriorate, especially near the carbon K edge. The photon flux losses due to carbon contamination have spurred researchers to search for a suitable decontamination technique to restore the optical surface and retain its performance. Several in situ and ex situ refurbishing strategies for beamline optics are still under development to solve this serious issue. In this work, the carbon contamination is removed from a large (340   mm × 60   mm) Au-coated toroidal mirror surface using a capacitively couple...
Source: Journal of Synchrotron Radiation - May 17, 2019 Category: Physics Authors: Yadav, P.K. Kumar, M. Gupta, R.K. Sinha, M. Chakera, J.A. Modi, M.H. Tags: synchrotron optics carbon contamination RF plasma soft X-ray reflectivity research papers Source Type: research

A beamline-compatible STED microscope for combined visible-light and X-ray studies of biological matter
A dedicated stimulated emission depletion (STED) microscope had been designed and implemented into the G ö ttingen Instrument for Nano-Imaging with X-rays (GINIX) at the synchrotron beamline P10 of the PETRA   III storage ring (DESY, Hamburg). The microscope was installed on the same optical table used for X-ray holography and scanning small-angle X-ray scattering (SAXS). Scanning SAXS was implemented with the Kirkpatrick – Baez (KB) nano-focusing optics of GINIX, while X-ray holography used a combined KB and X-ray waveguide optical system for full-field projection recordings at a defocus position of the objec...
Source: Journal of Synchrotron Radiation - May 17, 2019 Category: Physics Authors: Bernhardt, M. Nicolas, J.-D. Osterhoff, M. Mittelst ä dt, H. Reuss, M. Harke, B. Wittmeier, A. Sprung, M. K ö ster, S. Salditt, T. Tags: STED microscope X-ray holography scanning SAXS correlative microscopy X-ray microscopy in situ STED microscopy research papers Source Type: research

Commissioning of a photoelectron spectrometer for soft X-ray photon diagnostics at the European XFEL
The objective with the instrument is to provide the users and operators with reliable pulse-resolved information regarding photon energy and polarization that opens up a variety of applications for novel experiments but also hardware optimization. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - May 15, 2019 Category: Physics Authors: Laksman, J. Buck, J. Glaser, L. Planas, M. Dietrich, F. Liu, J. Maltezopoulos, T. Scholz, F. Seltmann, J. Hartmann, G. Ilchen, M. Freund, W. Kujala, N. Viefhaus, J. Gr ü nert, J. Tags: photon diagnostics photoelectron spectrometer polarimeter EuXFEL research papers Source Type: research

Multimodal X-ray imaging of grain-level properties and performance in a polycrystalline solar cell
The factors limiting the performance of alternative polycrystalline solar cells as compared with their single-crystal counterparts are not fully understood, but are thought to originate from structural and chemical heterogeneities at various length scales. Here, it is demonstrated that multimodal focused nanobeam X-ray microscopy can be used to reveal multiple aspects of the problem in a single measurement by mapping chemical makeup, lattice structure and charge collection efficiency simultaneously in a working solar cell. This approach was applied to micrometre-sized individual grains in a Cu(In,Ga)Se2 polycrystalline fil...
Source: Journal of Synchrotron Radiation - May 14, 2019 Category: Physics Authors: Ulvestad, A. Hruszkewycz, S.O. Holt, M.V. Hill, M.O. Calvo-Almaz á n, I. Maddali, S. Huang, X. Yan, H. Nazaretski, E. Chu, Y.S. Lauhon, L.J. Rodkey, N. Bertoni, M.I. Stuckelberger, M.E. Tags: solar cell materials scanning nanodiffraction X-ray-beam-induced current multimodal characterization research papers Source Type: research

Probing disorder in high-pressure cubic tin (IV) oxide: a combined X-ray diffraction and absorption study
The transparent conducting oxide, SnO2, is a promising optoelectronic material with predicted tailorable properties via pressure-mediated band gap opening. While such electronic properties are typically modeled assuming perfect crystallinity, disordering of the O sublattice under pressure is qualitatively known. Here a quantitative approach is thus employed, combining extended X-ray absorption fine-structure (EXAFS) spectroscopy with X-ray diffraction, to probe the extent of Sn — O bond anharmonicities in the high-pressure cubic (Pa\bar{3}) SnO2 – formed as a single phase and annealed by CO2 laser heating to 26...
Source: Journal of Synchrotron Radiation - May 14, 2019 Category: Physics Authors: Sneed, D. Kearney, J.S.C. Smith, D. Smith, J.S. Park, C. Salamat, A. Tags: extreme conditions EXAFS XRD laser heating SnO2 diamond anvil cell high pressure research papers Source Type: research

Hard and soft X-ray imaging to resolve human ovarian cortical structures
This study reports the first imaging of human ovarian tissue where the samples consisted of surgically obtained millimetre fragments, properly fixed, stained with osmium tetroxide and included in epoxydic resin. Samples were imaged by the use of propagation phase contrast synchrotron radiation micro-computed tomography (microCT), obtained at the SYRMEP beamline of Elettra light source (Trieste, Italy), and X-ray absorption microCT at the Theoretical Biology MicroCT Imaging Laboratory in Vienna, Austria. The reconstructed microCT images were compared with the soft X-ray absorption and phase contrast images acquired at the T...
Source: Journal of Synchrotron Radiation - May 14, 2019 Category: Physics Authors: Pascolo, L. Sena, G. Gianoncelli, A. Cernogoraz, A. Kourousias, G. Metscher, B.D. Romano, F. Zito, G. Pacil è , S. Barroso, R. Tromba, G. Zweyer, M. Ricci, G. Tags: microtomography phase contrast tomography STXM ovary research papers Source Type: research

Direct measurement of X-ray-induced heating of   microcrystals
Temperature control is a key aspect of macromolecular crystallography, with the technique of cryocooling routinely being used to mitigate X-ray-induced damage. Beam-induced heating could cause the temperature of crystals to rise above the glass transition temperature, greatly increasing the rate of damage. X-ray-induced heating of ruby crystals of 20 – 40   µ m in size has been quantified non-invasively by monitoring the emission wavelengths of X-ray-induced fluorescence during exposure to the X-ray beam. For the beam sizes and dose rates typically used in macromolecular crystallography, the temperature rises...
Source: Journal of Synchrotron Radiation - May 14, 2019 Category: Physics Authors: Warren, A.J. Axford, D. Owen, R.L. Tags: X-ray-induced beam heating fluorescence cryocooling research papers Source Type: research

SwissFEL Aramis beamline photon diagnostics. Erratum
The list of authors in the paper by Jurani ć et al. (2018) [J. Synchrotron Rad. 25, 1238 – 1248] is corrected. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 29, 2019 Category: Physics Authors: Jurani ć , P. Rehanek, J. Arrell, C.A. Pradervand, C. Cassar, A. Calvi, M. Ischebeck, R. Erny, C. Heimgartner, P. Gorgisyan, I. Thominet, V. Tiedtke, K. Sorokin, A. Follath, R. Makita, M. Seniutinas, G. David, C. Milne, C.J. Lemke, H. Radovic, M. Hauri, Tags: FEL physics photon diagnostics instrumentation hard X-rays addenda and errata Source Type: research

Wavefront-propagation simulations supporting the design of a time-delay compensating monochromator beamline at FLASH2
Wavefront-propagation simulations have been performed to complete the design of a monochromator beamline for FLASH2, the variable-gap undulator line at the soft X-ray free-electron laser in Hamburg (FLASH). Prior to propagation through the beamline optical elements, the parameters of the photon source were generated using the GENESIS code which includes the free-electron laser experimental data. Threshold tolerances for the misalignment of mirror angles are calculated and, since diffraction effects were included in the simulations, the minimum quality with respect to the slope errors required for the optics is determined. ...
Source: Journal of Synchrotron Radiation - April 26, 2019 Category: Physics Authors: Ruiz-Lopez, M. Samoylova, L. Brenner, G. Mehrjoo, M. Faatz, B. Kuhlmann, M. Poletto, L. Pl ö njes, E. Tags: wavefront propagation monochromators diffraction gratings ultrafast optics wavefront simulations free-electron lasers beamlines Source Type: research

Photon diagnostics at the FLASH THz beamline
The THz beamline at FLASH, DESY, provides both tunable (1 – 300   THz) narrow-bandwidth ( ∼ 10%) and broad-bandwidth intense (up to 150 uJ) THz pulses delivered in 1   MHz bursts and naturally synchronized with free-electron laser X-ray pulses. Combination of these pulses, along with the auxiliary NIR and VIS ultrashort lasers, supports a plethora of dynamic investigations in physics, material science and biology. The unique features of the FLASH THz pulses and the accelerator source, however, bring along a set of challenges in the diagnostics of their key parameters: pulse energy, spectral, temporal and spat...
Source: Journal of Synchrotron Radiation - April 26, 2019 Category: Physics Authors: Pan, R. Zapolnova, E. Golz, T. Krmpot, A.J. Rabasovic, M.D. Petrovic, J. Asgekar, V. Faatz, B. Tavella, F. Perucchi, A. Kovalev, S. Green, B. Geloni, G. Tanikawa, T. Yurkov, M. Schneidmiller, E. Gensch, M. Stojanovic, N. Tags: FLASH intense THz THz diagnostic electro-optic FTIR research papers Source Type: research

Pump – probe experimental methodology at the Linac Coherent Light Source
Experimental methods that use free-electron laser (FEL) sources that can deliver short X-ray pulses below a 10   fs pulse duration and traditional optical lasers are ideal tools for pump – probe experiments. However, these new methods also come with a unique set of challenges, such as how to accurately determine temporal overlap between two sources at the femtosecond scale and how to correct for the pulse-to-pulse beam property fluctuations of the FEL light derived from the self-amplified spontaneous emission process. Over the past several years of performing pump – probe experiments at the Linac Coherent Lig...
Source: Journal of Synchrotron Radiation - April 26, 2019 Category: Physics Authors: Glownia, J.M. Gumerlock, K. Lemke, H.T. Sato, T. Zhu, D. Chollet, M. Tags: XFELs X-ray free-electron lasers ultrafast lasers pump – probe experiments research papers Source Type: research

Nature of cobalt species during the in situ sulfurization of Co(Ni)Mo/Al2O3 hydrodesulfurization catalysts
The evolution in local structure and electronic properties of cobalt was investigated during in situ sulfurization. Using a combination of 1s X-ray absorption (XAS) and 1s3p resonant inelastic X-ray scattering (RIXS), the valence, coordination and symmetry of cobalt ions were tracked in two cobalt-promoted molybdenum oxide precursors of the hydrodesulfurization catalyst system, namely Co – Mo/Al2O3 and Co – Ni – Mo/Al2O3. Extended X-ray absorption fine structure shows that the Co — O bonds were replaced with Co — S bonds as a function of reaction temperature. The cobalt K pre-edge intensity sh...
Source: Journal of Synchrotron Radiation - April 26, 2019 Category: Physics Authors: al Samarai, M. van Oversteeg, C.H.M. Delgado-Jaime, M.U. Weng, T.- Sokaras, D. Liu, B. van der Linden, M. van der Eerden, A.M.J. Vogt, E.T.C. Weckhuysen, B.M. de Groot, F.M.F. Tags: heterogeneous catalysis hydrodesulfurization (HDS) catalyst systems CoMoS structure hydrotreating catalysts X-ray absorption spectroscopy resonant inelastic X-ray scattering (RIXS) research papers Source Type: research

Characterizing transmissive diamond gratings as beam splitters for the hard X-ray single-shot spectrometer of the European XFEL
The European X-ray Free Electron Laser (EuXFEL) offers intense, coherent femtosecond pulses, resulting in characteristic peak brilliance values a billion times higher than that of conventional synchrotron facilities. Such pulses result in extreme peak radiation levels of the order of terawatts   cm − 2 for any optical component in the beam and can exceed the ablation threshold of many materials. Diamond is considered the optimal material for such applications due to its high thermal conductivity (2052   W   mK − 1 at 300   K) and low absorption for hard X-rays. Grating structures were fabricated on free...
Source: Journal of Synchrotron Radiation - April 26, 2019 Category: Physics Authors: Kujala, N. Makita, M. Liu, J. Zozulya, A. Sprung, M. David, C. Gr ü nert, J. Tags: CVD diamond free-standing diamond membrane X-ray free-electron laser photon diagnostics diffraction efficiency grating structures HIREX diagnostic spectrometer research papers Source Type: research

Probing the spatial coherence of wide X-ray beams with Fresnel mirrors at BL25SU of SPring-8
In this study, a Fresnel-mirror-based optical system was constructed at the soft X-ray beamline (BL25SU) of SPring-8.   The relationship between the coherence and size of the virtual source was quantitatively measured at 300   eV in both the vertical and horizontal directions using the beam. The results obtained indicate that this is a valuable method for the optimization of optical systems along beamlines. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 23, 2019 Category: Physics Authors: Takeo, Y. Motoyama, H. Senba, Y. Kishimoto, H. Ohashi, H. Mimura, H. Tags: spatial coherence Fresnel mirrors soft X-rays research papers Source Type: research

A convolutional neural network for fast upsampling of undersampled tomograms in X-ray CT time-series using a representative highly sampled tomogram
X-ray computed tomography and, specifically, time-resolved volumetric tomography data collections (4D datasets) routinely produce terabytes of data, which need to be effectively processed after capture. This is often complicated due to the high rate of data collection required to capture at sufficient time-resolution events of interest in a time-series, compelling the researchers to perform data collection with a low number of projections for each tomogram in order to achieve the desired `frame rate'. It is common practice to collect a representative tomogram with many projections, after or before the time-critical portion...
Source: Journal of Synchrotron Radiation - April 23, 2019 Category: Physics Authors: Bellos, D. Basham, M. Pridmore, T. French, A.P. Tags: convolutional neural networks projection upsampling sinogram upscaling time-resolved X-ray computed tomography research papers Source Type: research

The SASE1 X-ray beam transport system
SASE1 is the first beamline of the European XFEL that became operational in 2017. It consists of the SASE1 undulator system, the beam transport system, and the two scientific experiment stations: Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX), and Femtosecond X-ray Experiments (FXE). The beam transport system comprises mirrors to offset and guide the beam to the instruments and a set of X-ray optical components to align, manipulate and diagnose the beam. The SASE1 beam transport system is described here in its initial configuration, and results and experiences from the first y...
Source: Journal of Synchrotron Radiation - April 17, 2019 Category: Physics Authors: Sinn, H. Dommach, M. Dickert, B. Di Felice, M. Dong, X. Eidam, J. Finze, D. Freijo-Martin, I. Gerasimova, N. Kohlstrunk, N. La Civita, D. Meyn, F. Music, V. Neumann, M. Petrich, M. Rio, B. Samoylova, L. Schmidtchen, S. St ö rmer, M. Trapp, A. Vannoni, M. Tags: XFEL physics photon beamlines hard X-rays beam transport systems X-ray optical components research papers Source Type: research

A middle energy-bandwidth X-ray monochromator for high-flux synchrotron diffraction: revisiting asymmetrically cut silicon crystals
To supply the growing demand for high photon flux in synchrotron science including surface diffraction, a middle energy-bandwidth monochromator covering the 10 − 4 to 10 − 3 range has been adapted by applying an asymmetric diffraction geometry to a cryogenically cooled silicon 111 double-crystal monochromator used as a standard for the undulator source at SPring-8. The asymmetric geometry provides a great advantage with its ability to configure flux gains over a wide energy range by simply changing the asymmetry angle, while the angular divergence of the exit beam remains unchanged. A monolithic design with thr...
Source: Journal of Synchrotron Radiation - April 17, 2019 Category: Physics Authors: Tajiri, H. Yamazaki, H. Ohashi, H. Goto, S. Sakata, O. Ishikawa, T. Tags: X-ray monochromators double-crystal monochromators asymmetric geometry middle energy-bandwidth silicon crystals high-flux diffraction research papers Source Type: research

Laser systems for time-resolved experiments at the Pohang Accelerator Laboratory X-ray Free-Electron Laser beamlines
Optical laser systems for ultrafast X-ray sciences have been established at the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) beamlines. Three Ti:sapphire regenerative amplifier systems are synchronized to the XFEL with femtosecond precision, and the low temporal jitter of the PAL-XFEL results in an experimental time resolution below 150   fs (full width at half-maximum). A fundamental wave and its harmonics are currently provided for all beamlines, and tunable sources from ultraviolet to near-infrared are available for one beamline. The position stability of the optical laser extracted from the inte...
Source: Journal of Synchrotron Radiation - April 15, 2019 Category: Physics Authors: Kim, M. Min, C.-K. Eom, I. Tags: XFELs time-resolved XFEL experiments optical lasers beamlines amplifier systems fundamental waves Source Type: research

Experimental station Bernina at SwissFEL: condensed matter physics on femtosecond time scales investigated by X-ray diffraction and spectroscopic methods
The Bernina instrument at the SwissFEL Aramis hard X-ray free-electron laser is designed for studying ultrafast phenomena in condensed matter and material science. Ultrashort pulses from an optical laser system covering a large wavelength range can be used to generate specific non-equilibrium states, whose subsequent temporal evolution can be probed by selective X-ray scattering techniques in the range 2 – 12   keV. For that purpose, the X-ray beamline is equipped with optical elements which tailor the X-ray beam size and energy, as well as with pulse-to-pulse diagnostics that monitor the X-ray pulse intensity, pos...
Source: Journal of Synchrotron Radiation - April 15, 2019 Category: Physics Authors: Ingold, G. Abela, R. Arrell, C. Beaud, P. B ö hler, P. Cammarata, M. Deng, Y. Erny, C. Esposito, V. Flechsig, U. Follath, R. Hauri, C. Johnson, S. Juranic, P. Mancini, G.F. Mankowsky, R. Mozzanica, A. Oggenfuss, R.A. Patterson, B.D. Patthey, L. Pedrini, Tags: FEL X-ray pump – probe time-resolved beamlines Source Type: research

Synchrotron radiation micro-tomography for high-resolution neurovascular network morphology investigation
There has been increasing interest in using high-resolution micro-tomography to investigate the morphology of neurovascular networks in the central nervous system, which remain difficult to characterize due to their microscopic size as well as their delicate and complex 3D structure. Synchrotron radiation X-ray imaging, which has emerged as a cutting-edge imaging technology with a high spatial resolution, provides a novel platform for the non-destructive imaging of microvasculature networks at a sub-micrometre scale. When coupled with computed tomography, this technique allows the characterization of the 3D morphology of v...
Source: Journal of Synchrotron Radiation - April 15, 2019 Category: Physics Authors: Cao, Y. Zhang, M. Ding, H. Chen, Z. Tang, B. Wu, T. Xiao, B. Duan, C. Ni, S. Jiang, L. Luo, Z. Li, C. Zhao, J. Liao, S. Yin, X. Fu, Y. Xiao, T. Lu, H. Hu, J. Tags: high-resolution imaging neurovascular network 3D topical reviews Source Type: research

Time-resolved X-ray reflection phases of the nearly forbidden Si(222) reflection under laser excitation
The covalent electron density, which makes Si(222) measurable, is subject to laser excitation. The three-wave Si(222)/(13 {\overline 1}) diffraction at 7.82   keV is used for phase measurements. It is found that laser excitation causes a relative phase change of around 4 ° in Si(222) in the first 100   ps of excitation and this is gradually recovered over several nanoseconds. This phase change is due to laser excitation of covalent electrons around the silicon atoms in the unit cell and makes the electron density deviate further from the centrosymmetric distribution. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 12, 2019 Category: Physics Authors: Tsai, Y.-W. Chang, Y.-Y. Lee, J.-J. Liu, W.-C. Wu, Y.-H. Liu, W.-R. Liu, H.-Y. Lee, K.-Y. Weng, S.-C. Sheu, H.-S. Chiu, M.-S. Lee, Y.-Y. Hsu, C.-H. Chang, S.-L. Tags: pump – probe experiments X-ray reflection phases three-wave diffraction laser excitation covalent electron density research papers Source Type: research

Angular dispersion enhanced prebunch for seeding ultrashort and coherent EUV and soft X-ray free-electron laser in storage rings
Prebunching is an effective technique to reduce the radiation saturation length and to improve the longitudinal coherence and output stability in storage-ring-based free-electron lasers (FELs). A novel technique is proposed which uses angular dispersion to enhance the high-harmonic bunching with very small laser-induced energy spread. This technique can effectively reduce the radiation saturation length without significantly reducing the peak power of the FEL. Numerical simulations demonstrate that this technique can be used for the generation of 100   MW scale level, fully temporal coherent femtosecond extreme-ultraviol...
Source: Journal of Synchrotron Radiation - April 12, 2019 Category: Physics Authors: Wang, X. Feng, C. Liu, T. Zhang, Z. Tsai, C.-Y. Wu, J. Yang, C. Zhao, Z. Tags: angular dispersion storage rings free-electron lasers extreme-ultraviolet (EUV) ultrashort prebunching high-harmonic bunching radiation saturation length research papers Source Type: research

The Single Particles, Clusters and Biomolecules and Serial Femtosecond Crystallography instrument of the European XFEL: initial installation
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 experim...
Source: Journal of Synchrotron Radiation - April 12, 2019 Category: Physics Authors: Mancuso, A.P. Aquila, A. Batchelor, L. Bean, R.J. Bielecki, J. Borchers, G. Doerner, K. Giewekemeyer, K. Graceffa, R. Kelsey, O.D. Kim, Y. Kirkwood, H.J. Legrand, A. Letrun, R. Manning, B. Lopez Morillo, L. Messerschmidt, M. Mills, G. Raabe, S. Reimers, N Tags: XFEL serial crystallography instrumentation research papers Source Type: research

Compact undulator line for a high-brilliance soft-X-ray free-electron laser at MAX IV
This study focuses on FEL operation with a shorter undulator period and higher undulator strength made available through recent developments in in-vacuum, cryogenic and superconducting undulators. Progress on short-period undulator technologies is surveyed and FEL output characteristics versus undulator parameters are computed. The study is performed on a case of the planned soft-X-ray FEL at the MAX IV Laboratory in Sweden. An extension of the SASE mode into the harmonic lasing self-seeded mode is also analysed. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 11, 2019 Category: Physics Authors: Mak, A. Sal é n, P. Goryashko, V. Tags: undulator technologies X-ray free-electron lasers high brilliance self-amplified spontaneous emission harmonic lasing self-seeding beamlines Source Type: research

Native mass spectrometry provides sufficient ion flux for XFEL single-particle imaging
The SPB/SFX instrument at the European XFEL provides unique conditions for single-particle imaging (SPI) experiments due to its high brilliance, nano-focus and unique pulse structure. Promising initial results provided by the international LCLS (Linac Coherent Light Source) SPI initiative highlight the potential of SPI. Current available injection methods generally have high sample consumption and do not provide any options for pulsing, selection or orientation of particles, which poses a problem for data evaluation. Aerosol-injector-based sample delivery is the current method of choice for SPI experiments, although, to a ...
Source: Journal of Synchrotron Radiation - April 11, 2019 Category: Physics Authors: Uetrecht, C. Lorenzen, K. Kitel, M. Heidemann, J. Spencer, J.H. Schl ü ter, H. Schulz, J. Tags: SPI electrospray Ionization X-ray free-electron lasers native MS structural biology research papers Source Type: research

Dynamical effects on superradiant THz emission from an undulator
Superradiant emission occurs when ultra-relativistic electron bunches are compressed to a duration shorter than the wavelength of the light emitted by them. In this case the different electron contributions to the emitted field sum up in phase and the output intensity scales as the square of the number of electrons in the bunch. In this work the particular case of superradiant emission from an undulator in the THz frequency range is considered. An electron bunch at the entrance of a THz undulator setup has typically an energy chirp because of the necessity to compress it in magnetic chicanes. Then, the chirped electron bun...
Source: Journal of Synchrotron Radiation - April 11, 2019 Category: Physics Authors: Geloni, G. Tanikawa, T. Tomin, S. Tags: undulator radiation superradiant emission chirped electron bunch dispersion research papers Source Type: research

Reaction microscope endstation at FLASH2
A reaction microscope dedicated to multi-particle coincidence spectroscopy on gas-phase samples is installed at beamline FL26 of the free-electron laser FLASH2 in Hamburg. The main goals of the instrument are to follow the dynamics of atoms, molecules and small clusters on their natural time-scale and to study non-linear light – matter interaction with such systems. To this end, the reaction microscope is combined with an in-line extreme-ultraviolet (XUV) split-delay and focusing optics, which allows time-resolved XUV-XUV pump – probe spectroscopy to be performed. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 9, 2019 Category: Physics Authors: Schmid, G. Schnorr, K. Augustin, S. Meister, S. Lindenblatt, H. Trost, F. Liu, Y. Braune, M. Treusch, R. Schr ö ter, C.D. Pfeifer, T. Moshammer, R. Tags: time-resolved molecular dynamics non-linear light – matter interaction reaction microscope multi-particle coincidence spectroscopy free-electron laser XUV XUV pump probe spectroscopy beamlines Source Type: research

A flexible cell for in situ combined XAS – DRIFTS – MS experiments
A new cell for in situ combined X-ray absorption, diffuse reflectance IR Fourier transform and mass spectroscopies (XAS – DRIFTS – MS) is presented. The cell stands out among others for its achievements and flexibility. It is possible to perform XAS measurements in transmission or fluorescence modes, and the cell is compatible with external devices like UV-light and Raman probes. It includes different sample holders compatible with the different XAS detection modes, different sample forms (free powder or self-supporting pellet) and different sample loading/total absorption. Additionally, it has a small dead vol...
Source: Journal of Synchrotron Radiation - April 9, 2019 Category: Physics Authors: Meira, D.M. Monte, M. Fern á ndez-Garc í a, M. Meunier, F. Mathon, O. Pascarelli, S. Agostini, G. Tags: fluorescence mode multi-technique characterization in situ characterization coupled experiments XAS – DRIFTS MS research papers Source Type: research

A piezoelectric deformable X-ray mirror for phase compensation based on global optimization
As a strong tool for the study of nanoscience, the synchrotron hard X-ray nanoprobe technique enables researchers to investigate complex samples with many advantages, such as in   situ setup, high sensitivity and the integration of various experimental methods. In recent years, an important goal has been to push the focusing spot size to the diffraction limit of ∼ 10   nm. The multilayer-based Kirkpatrick – Baez (KB) mirror system is one of the most important methods used to achieve this goal. This method was chosen by the nanoprobe beamline of the Phase-II project at the Shanghai Synchrotron Radiation Facili...
Source: Journal of Synchrotron Radiation - April 9, 2019 Category: Physics Authors: Jiang, H. Tian, N. Liang, D. Du, G. Yan, S. Tags: piezoelectric deformable mirror phase compensation figure error speckle scanning metrology iterative global optimization research papers Source Type: research

A statistical approach to correct X-ray response non-uniformity in microstrip detectors for high-accuracy and high-resolution total-scattering measurements
An unbiased approach to correct X-ray response non-uniformity in microstrip detectors has been developed based on the statistical estimation that the scattering intensity at a fixed angle from an object is expected to be constant within the Poisson noise. Raw scattering data of SiO2 glass measured by a microstrip detector module was found to show an accuracy of 12 σ PN at an intensity of 106 photons, where σ PN is the standard deviation according to the Poisson noise. The conventional flat-field calibration has failed in correcting the data, whereas the alternative approach used in this article successfully imp...
Source: Journal of Synchrotron Radiation - April 5, 2019 Category: Physics Authors: Kato, K. Tanaka, Y. Yamauchi, M. Ohara, K. Hatsui, T. Tags: total scattering pair distribution functions microstrip detectors flat-field calibration Poisson noise research papers Source Type: research