Pulse intensity characterization of the LCLS nanosecond double-bunch mode of operation
The recent demonstration of the `nanosecond double-bunch' operation mode, i.e. two X-ray pulses separated in time between 0.35 and hundreds of nanoseconds and by increments of 0.35   ns, offers new opportunities to investigate ultrafast dynamics in diverse systems of interest. However, in order to reach its full potential, this mode of operation requires the precise characterization of the intensity of each X-ray pulse within each pulse pair for any time separation. Here, a transmissive single-shot diagnostic that achieves this goal for time separations larger than 0.7   ns with a precision better than 5% is presented....
Source: Journal of Synchrotron Radiation - March 27, 2018 Category: Physics Authors: Sun, Y. Decker, F.-J. Turner, J. Song, S. Robert, A. Zhu, D. Tags: FEL X-ray XSVS speckle XPCS research papers Source Type: research

Hybrid modelling of a high-power X-ray attenuator plasma
X-ray gas attenuators act as stress-free high-pass filters for synchrotron and free-electron laser beamlines to reduce the heat load in downstream optical elements without affecting other properties of the X-ray beam. The absorption of the X-ray beam triggers a cascade of processes that ionize and heat up the gas locally, changing its density and therefore the X-ray absorption. Aiming to understand and predict the behaviour of the gas attenuator in terms of efficiency versus gas pressure, a hybrid model has been developed, combining three approaches: an analytical description of the X-ray absorption; Monte Carlo for the el...
Source: Journal of Synchrotron Radiation - March 27, 2018 Category: Physics Authors: Mart í n Ortega, Á . Lacoste, A. Minea, T. Tags: gas attenuator X-ray absorption plasma model fluid model Monte Carlo research papers Source Type: research

Quantitative study of the influence of swimming therapy on osteoporosis rat models based on synchrotron radiation computed tomogaphy
Osteoporosis is a bone disease with a variety of causes, leading to bone pain and fragility to fracture. Major treatment methods include nutrition therapy, exercise therapy, drug therapy and surgical treatment, among which exercise therapy, such as swimming, is the most effective. To investigate the optimal swimming therapy regime for postmenopausal women, the effects of eight weeks of different intensity swimming exercises were studied in rat models. After the swimming program, lumbar vertebrae were dissected from all the rats and scanned by synchrotron radiation computed tomography (SRCT). Histomorphometry analysis and f...
Source: Journal of Synchrotron Radiation - March 27, 2018 Category: Physics Authors: Huang, L. Xu, J. Guo, H. Wang, Y. Zhao, J. Sun, J. Tags: swimming different intensities bone strength research papers Source Type: research

A scanning transmission X-ray microscope at the Pohang Light Source
A scanning transmission X-ray microscope is operational at the 10A beamline at the Pohang Light Source. The 10A beamline provides soft X-rays in the photon energy range 100 – 2000   eV using an elliptically polarized undulator. The practically usable photon energy range of the scanning transmission X-ray microscopy (STXM) setup is from ∼ 150 to ∼ 1600   eV. With a zone plate of 25   nm outermost zone width, the diffraction-limited space resolution, ∼ 30   nm, is achieved in the photon energy range up to ∼ 850   eV. In transmission mode for thin samples, STXM provides the element, chemical st...
Source: Journal of Synchrotron Radiation - March 15, 2018 Category: Physics Authors: Shin, H.-J. Kim, N. Kim, H.-S. Lee, W.-W. Lee, C.-S. Kim, B. Tags: STXM spectronanoscopy spectromicroscopy soft X-ray fluorescence beamlines Source Type: research

X-ray beam-position feedback system with easy-to-use beam-position monitor
X-ray beam-position stability is indispensable in cutting-edge experiments using synchrotron radiation. Here, for the first time, a beam-position feedback system is presented that utilizes an easy-to-use X-ray beam-position monitor incorporating a diamond-fluorescence screen. The acceptable range of the monitor is above 500   µ m and the feedback system maintains the beam position within 3   µ m. In addition to being inexpensive, the system has two key advantages: it works without a scale factor for position calibration, and it has no dependence on X-ray energy, X-ray intensity, beam size or beam shape. (So...
Source: Journal of Synchrotron Radiation - March 14, 2018 Category: Physics Authors: Park, J.Y. Kim, Y. Lee, S. Lim, J. Tags: X-ray beam-position monitor diamond-fluorescence screen feedback system short communications Source Type: research

Influence of the core-hole effect on optical properties of magnesium oxide (MgO) near the Mg L-edge region
The influence of the core-hole effect on optical properties of magnesium oxide (MgO) is established through experimental determination of optical constants and first-principles density functional theory studies. Optical constants ( δ and β ) of MgO thin film are measured in the spectral region 40 – 300   eV using reflectance spectroscopy techniques at the Indus-1 synchrotron radiation source. The obtained optical constants show strong core exciton features near the Mg L-edge region, causing significant mismatch with Henke's tabulated values. On comparing the experimentally obtained optical constants with...
Source: Journal of Synchrotron Radiation - March 14, 2018 Category: Physics Authors: Sinha, M. Modi, M.H. Ghosh, H. Yadav, P.K. Gupta, R.K. Tags: synchrotron radiation soft X-ray magnesium compound core-hole effect optical property research papers Source Type: research

Beam-induced redox transformation of arsenic during As K-edge XAS measurements: availability of reducing or oxidizing agents and As speciation
In this study, the As species immobilized by poorly crystallized mackinawite (FeS) was assessed for the susceptibility to beam-induced redox reactions as a function of sample properties including the redox state of FeS and the solid-phase As speciation. The beam-induced oxidation of reduced As species was found to be mediated by the atmospheric O2 and the oxidation products of FeS [e.g. Fe(III) (oxyhydr)oxides and intermediate sulfurs]. Regardless of the redox state of FeS, both arsenic sulfide and surface-complexed As(III) readily underwent the photo-oxidation upon exposure to the atmospheric O2 during XAS measurements. W...
Source: Journal of Synchrotron Radiation - March 14, 2018 Category: Physics Authors: Han, Y.-S. Jeong, H.Y. Hyun, S.P. Hayes, K.F. Chon, C.-M. Tags: X-ray absorption spectroscopy photocatalytic transformation mackinawite arsenic linear combination fitting research papers Source Type: research

Current events
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 28, 2018 Category: Physics Authors: , Tags: current events Source Type: research

Absorbed dose calculations for macromolecular crystals: improvements to RADDOSE. Erratum
Corrections to an equation and a figure in the paper by Paithankar et al. (2009). [J. Synchrotron Rad. 16, 152 – 162] are made. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 28, 2018 Category: Physics Authors: Paithankar, K.S. Owen, R.L. Garman, E.F. Tags: absorbed dose macromolecular crystallography experimental dose limit fluorescence escape photoelectric absorption addenda and errata Source Type: research

Commissioning of a multi-beamline femtoslicing facility at SOLEIL
The investigation of ultrafast dynamics, taking place on the few to sub-picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X-ray free-electron lasers (XFELs), providing very intense X-ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub-picosecond pulsed X-ray sources among which femtoslicing facilities at synchrotro...
Source: Journal of Synchrotron Radiation - February 28, 2018 Category: Physics Authors: Labat, M. Brubach, J.-B. Ciavardini, A. Couprie, M.-E. Elkaim, E. Fertey, P. Ferte, T. Hollander, P. Hubert, N. Jal, E. Laulh é , C. Luning, J. Marcouill é , O. Moreno, T. Morin, P. Polack, F. Prigent, P. Ravy, S. Ricaud, J.-P. Roy, P. Silly, M. Sirotti Tags: femtoslicing storage ring coherent THz research papers Source Type: research

An X-ray harmonic separator for next-generation synchrotron X-ray sources and X-ray free-electron lasers
An X-ray prism for the extraction of a specific harmonic of undulator radiation is proposed. By using the prism in a grazing incidence geometry, the beam axes of fundamental and harmonics of undulator radiation are separated with large angles over 10   µ rad, which enables the selection of a specific harmonic with the help of apertures, while keeping a high photon flux. The concept of the harmonic separation was experimentally confirmed using X-ray beams from the X-ray free-electron laser SACLA. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 28, 2018 Category: Physics Authors: Inoue, I. Osaka, T. Tamasaku, K. Ohashi, H. Yamazaki, H. Goto, S. Yabashi, M. Tags: harmonic radiation X-ray free-electron lasers diffraction-limited storage rings harmonic separation SACLA research papers Source Type: research

Hiromichi Kamitsubo (1933 – 2017)
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 28, 2018 Category: Physics Authors: Ishikawa, T. Hasnain, S. Tags: obituary SPring-8 RIKEN JASRI SACLA obituaries Source Type: research

Quantitative investigation of linear arbitrary polarization in an APPLE-II undulator
Insertion devices are utilized at synchrotron radiation facilities around the world for their capability to provide a high-brilliance X-ray beam. APPLE-II type undulators are especially important for their capacity to switch between a variety of photon beam polarization states. A high-precision soft X-ray polarimeter has been used to investigate the polarization calibration of an APPLE-II undulator (period length λ u = 64   mm) installed on beamline I06 at Diamond Light Source. Systematic measurement of the beam polarization state at a range of linear arbitrary angles has been compared with the expected result for...
Source: Journal of Synchrotron Radiation - February 22, 2018 Category: Physics Authors: Hand, M. Wang, H. Maccherozzi, F. Apollonio, M. Zhu, J. Dhesi, S.S. Sawhney, K. Tags: polarization multilayers synchrotron radiation undulators research papers Source Type: research

Real-space analysis of radiation-induced specific changes with independent component analysis
A method of analysis is presented that allows for the separation of specific radiation-induced changes into distinct components in real space. The method relies on independent component analysis (ICA) and can be effectively applied to electron density maps and other types of maps, provided that they can be represented as sets of numbers on a grid. Here, for glucose isomerase crystals, ICA was used in a proof-of-concept analysis to separate temperature-dependent and temperature-independent components of specific radiation-induced changes for data sets acquired from multiple crystals across multiple temperatures. ICA identif...
Source: Journal of Synchrotron Radiation - February 22, 2018 Category: Physics Authors: Borek, D. Bromberg, R. Hattne, J. Otwinowski, Z. Tags: independent component analysis (ICA) singular value decomposition (SVD) radiation damage tunnelling research papers Source Type: research

Evaluation of the UFXC32k photon-counting detector for pump – probe experiments using synchrotron radiation
This paper presents the performance of a single-photon-counting hybrid pixel X-ray detector with synchrotron radiation. The camera was evaluated with respect to time-resolved experiments, namely pump – probe – probe experiments held at SOLEIL. The UFXC camera shows very good energy resolution of around 1.5   keV and allows the minimum threshold setting to be as low as 3   keV keeping the high-count-rate capabilities. Measurements of a synchrotron characteristic filling mode prove the proper separation of an isolated bunch of photons and the usability of the detector in time-resolved experiments. (Source: Jo...
Source: Journal of Synchrotron Radiation - February 21, 2018 Category: Physics Authors: Koziol, A. Bordessoule, M. Ciavardini, A. Dawiec, A. Da Silva, P. Desjardins, K. Grybos, P. Kanoute, B. Laulhe, C. Maj, P. Menneglier, C. Mercere, P. Orsini, F. Szczygiel, R. Tags: pump – probe experiments UFXC32k single-photon counting pixel array detector high frame rate research papers Source Type: research

Automatic Debye – Scherrer elliptical ring extraction via a computer vision approach
The accurate calibration of powder diffraction data acquired from area detectors using calibration standards is a crucial step in the data reduction process to attain high-quality one-dimensional patterns. A novel algorithm has been developed for extracting Debye – Scherrer rings automatically using an approach based on computer vision and pattern recognition techniques. The presented technique requires no human intervention and, unlike previous approaches, makes no restrictive assumptions on the diffraction setup and/or rings. It can detect complete rings as well as portions of them, and works on several types of di...
Source: Journal of Synchrotron Radiation - February 21, 2018 Category: Physics Authors: Shahzad, S. Khan, N. Nawaz, Z. Ferrero, C. Tags: powder diffraction calibration 2D patterns computer vision research papers Source Type: research

A Li K-edge XANES study of salts and minerals
The first comprehensive Li K-edge XANES study of a varied suite of Li-bearing minerals is presented. Drastic changes in the bonding environment for lithium are demonstrated and this can be monitored using the position and intensity of the main Li K-absorption edge. The complex silicates confirm the assignment of the absorption edge to be a convolution of triply degenerate p-like states as previously proposed for simple lithium compounds. The Li K-edge position depends on the electronegativity of the element to which it is bound. The intensity of the first peak varies depending on the existence of a 2p electron and can be u...
Source: Journal of Synchrotron Radiation - February 21, 2018 Category: Physics Authors: O'Shaughnessy, C. Henderson, G.S. Moulton, B.J.A. Zuin, L. Neuville, D.R. Tags: XANES lithium silicates phosphates salts research papers Source Type: research

X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell
The effects of varying LiPF6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate – dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li+ ion concentration in the solvent ...
Source: Journal of Synchrotron Radiation - February 21, 2018 Category: Physics Authors: Ketenoglu, D. Spiekermann, G. Harder, M. Oz, E. Koz, C. Yagci, M.C. Yilmaz, E. Yin, Z. Sahle, C.J. Detlefs, B. Yava ş , H. Tags: non-resonant inelastic X-ray scattering lithium-ion battery electrolyte C and O K-edge spectra research papers Source Type: research

miXAFS: a program for X-ray absorption fine-structure data analysis
A new program called miXAFS for the analysis of X-ray absorption fine-structure (XAFS) data is presented. miXAFS can analyze the XAFS functions simultaneously for all measured X-ray absorption edges of the constituent elements in a sample under the constraints for the structural parameters over the edges. The program provides a surface plot of the R-factor as a function of two structural parameters, which is useful to validate the optimized structural parameters. The structural parameters can be obtained from the XAFS data in a few steps using the setting file and batch process. The program, which is coded in MATLAB and fr...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Ikemoto, H. Tags: XAFS analysis program multi-edge fitting computer programs Source Type: research

Real-time diffraction computed tomography data reduction
Diffraction imaging is an X-ray imaging method which uses the crystallinity information (cell parameter, orientation) as a signal to create an image pixel by pixel: a pencil beam is raster-scanned onto a sample and the (powder) diffraction signal is recorded by a large area detector. With the flux provided by third-generation synchrotrons and the speed of hybrid pixel detectors, the acquisition speed of these experiments is now limited by the transfer rate to the local storage as the data reduction can hardly be performed in real time. This contribution presents the benchmarking of a typical data analysis pipeline for a di...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Kieffer, J. Petitdemange, S. Vincent, T. Tags: powder diffraction diffraction imaging Pilatus detector image compression azimuthal integration pyFAI FabIO silx computer programs Source Type: research

Solid energy calibration standards for P K-edge XANES: electronic structure analysis of PPh4Br
P K-edge X-ray absorption near-edge structure (XANES) spectroscopy is a powerful method for analyzing the electronic structure of organic and inorganic phosphorus compounds. Like all XANES experiments, P K-edge XANES requires well defined and readily accessible calibration standards for energy referencing so that spectra collected at different beamlines or under different conditions can be compared. This is especially true for ligand K-edge X-ray absorption spectroscopy, which has well established energy calibration standards for Cl (Cs2CuCl4) and S (Na2S2O3 · 5H2O), but not neighboring P. This paper presents a revi...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Blake, A.V. Wei, H. Donahue, C.M. Lee, K. Keith, J.M. Daly, S.R. Tags: P K-edge XANES energy calibration standards ligand K-edge XAS time-dependent density functional theory research papers Source Type: research

Characterization of a quadrant diamond transmission X-ray detector including a precise determination of the mean electron – hole pair creation energy
Precise monitoring of the incoming photon flux is crucial for many experiments using synchrotron radiation. For photon energies above a few keV, thin semiconductor photodiodes can be operated in transmission for this purpose. Diamond is a particularly attractive material as a result of its low absorption. The responsivity of a state-of-the art diamond quadrant transmission detector has been determined, with relative uncertainties below 1% by direct calibration against an electrical substitution radiometer. From these data and the measured transmittance, the thickness of the involved layers as well as the mean electron &nda...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Keister, J.W. Cibik, L. Schreiber, S. Krumrey, M. Tags: X-ray detectors diamond calibration scattering quadrant diamond transmission X-ray detector research papers Source Type: research

A high-energy-resolution resonant inelastic X-ray scattering spectrometer at ID20 of the European Synchrotron Radiation Facility
An end-station for resonant inelastic X-ray scattering and (resonant) X-ray emission spectroscopy at beamline ID20 of ESRF – The European Synchrotron is presented. The spectrometer hosts five crystal analysers in Rowland geometry for large solid angle collection and is mounted on a rotatable arm for scattering in both the horizontal and vertical planes. The spectrometer is optimized for high-energy-resolution applications, including partial fluorescence yield or high-energy-resolution fluorescence detected X-ray absorption spectroscopy and the study of elementary electronic excitations in solids. In addition, it can ...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Moretti Sala, M. Martel, K. Henriquet, C. Al Zein, A. Simonelli, L. Sahle, C. Gonzalez, H. Lagier, M.-C. Ponchut, C. Huotari, S. Verbeni, R. Krisch, M. Monaco, G. Tags: resonant inelastic X-ray scattering X-ray emission ID20 beamline RIXS spectrometer ESRF research papers Source Type: research

Time-resolved ion imaging at free-electron lasers using TimepixCam
The application of a novel fast optical-imaging camera, TimepixCam, to molecular photoionization experiments using the velocity-map imaging technique at a free-electron laser is described. TimepixCam is a 256   ×   256 pixel CMOS camera that is able to detect and time-stamp ion hits with 20   ns timing resolution, thus making it possible to record ion momentum images for all fragment ions simultaneously and avoiding the need to gate the detector on a single fragment. This allows the recording of significantly more data within a given amount of beam time and is particularly useful for pump – probe experime...
Source: Journal of Synchrotron Radiation - February 20, 2018 Category: Physics Authors: Fisher-Levine, M. Boll, R. Ziaee, F. Bomme, C. Erk, B. Rompotis, D. Marchenko, T. Nomerotski, A. Rolles, D. Tags: time-stamping camera velocity map imaging VMI free-electron laser FEL ultrafast laser pump – probe experiments mass spectrometry research papers Source Type: research

Finite lifetime broadening of calculated X-ray absorption spectra: possible artefacts close to the   edge
X-ray absorption spectra calculated within an effective one-electron approach have to be broadened to account for the finite lifetime of the core hole. For methods based on Green's function this can be achieved either by adding a small imaginary part to the energy or by convoluting the spectra on the real axis with a Lorentzian. By analyzing the Fe K- and L2,3-edge spectra it is demonstrated that these procedures lead to identical results only for energies higher than a few core-level widths above the absorption edge. For energies close to the edge, spurious spectral features may appear if too much weight is put on broaden...
Source: Journal of Synchrotron Radiation - February 19, 2018 Category: Physics Authors: Š ipr, O. Vack á r, J. Min á r, J. Tags: X-ray absorption spectroscopy core hole lifetime multiple-scattering formalism research papers Source Type: research

Tris-amidoximate uranyl complexes via η 2 binding mode coordinated in aqueous solution shown by X-ray absorption spectroscopy and density functional theory methods
The present study sheds some light on the long-standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X-ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl – amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO22+ and the amidoxime ligand is η 2 coordination with tris-amidoximate species. In such ...
Source: Journal of Synchrotron Radiation - February 19, 2018 Category: Physics Authors: Zhang, L. Qie, M. Su, J. Zhang, S. Zhou, J. Li, J. Wang, Y. Yang, S. Wang, S. Li, J. Wu, G. Wang, J.-Q. Tags: uranyl speciation X-ray absorption near-edge structure XANES extended X-ray absorption fine structure EXAFS local coordination structure amidoxime ligand DFT calculations research papers Source Type: research

Counting-loss correction for X-ray spectroscopy using unit impulse pulse shaping
High-precision measurement of X-ray spectra is affected by the statistical fluctuation of the X-ray beam under low-counting-rate conditions. It is also limited by counting loss resulting from the dead-time of the system and pile-up pulse effects, especially in a high-counting-rate environment. In this paper a detection system based on a FAST-SDD detector and a new kind of unit impulse pulse-shaping method is presented, for counting-loss correction in X-ray spectroscopy. The unit impulse pulse-shaping method is evolved by inverse deviation of the pulse from a reset-type preamplifier and a C-R shaper. It is applied to obtain...
Source: Journal of Synchrotron Radiation - February 19, 2018 Category: Physics Authors: Hong, X. Zhou, J. Ni, S. Ma, Y. Yao, J. Zhou, W. Liu, Y. Wang, M. Tags: counting loss correction X-ray spectroscopy unit impulse pulse shaping FAST-SDD detector research papers Source Type: research

Compact coherence enhancement by subharmonic self-seeding in X-ray free-electron laser facilities
X-ray free-electron lasers (FELs) are cutting-edge scientific tools able to generate transversely coherent radiation with very high power and ultra-short pulse durations. The self-seeding mechanism has been proven to increase the longitudinal coherence of the FEL radiation but its efficiency could be significantly improved, especially for soft X-rays. This paper proposes the enhancement of the performance of self-seeding by combining it with the harmonic generation mechanism. In particular, by starting the process with a subharmonic of the wavelength of interest, the coherence of the produced radiation is improved, the und...
Source: Journal of Synchrotron Radiation - February 19, 2018 Category: Physics Authors: Prat, E. Reiche, S. Tags: free-electron laser self-seeding X-ray coherence simulations research papers Source Type: research

Multifarious injection chamber for molecular structure study (MICOSS) system: development and application for serial femtosecond crystallography at Pohang Accelerator Laboratory X-ray Free-Electron Laser
The multifarious injection chamber for molecular structure study (MICOSS) experimental system has been developed at the Pohang Accelerator Laboratory X-ray Free-Electron Laser for conducting serial femtosecond crystallography. This system comprises several instruments such as a dedicated sample chamber, sample injectors, sample environment diagnostic system and detector stage for convenient distance manipulation. Serial femtosecond crystallography experiments of lysozyme crystals have been conducted successfully. The diffraction peaks have reached to ∼ 1.8   Å resolution at the photon energy of 9.785   keV. (...
Source: Journal of Synchrotron Radiation - February 19, 2018 Category: Physics Authors: Park, J. Kim, S. Kim, S. Nam, K.H. Tags: serial femtosecond crystallography PAL-XFEL lysozyme NCI sample injector MICOSS research papers Source Type: research

X-ray reflectivity from curved liquid interfaces
X-ray reflectivity studies of the structure of liquid – vapour and liquid – liquid interfaces at modern sources, such as free-electron lasers, are currently impeded by the lack of dedicated liquid surface diffractometers. It is shown that this obstacle can be overcome by an alternative experimental approach that uses the natural curvature of a liquid drop for variation of the angle of incidence. Two modes of operation are shown: (i) sequential reflectivity measurements by a nanometre beam and (ii) parallel acquisition of large ranges of a reflectivity curve by micrometre beams. The feasibility of the two method...
Source: Journal of Synchrotron Radiation - February 16, 2018 Category: Physics Authors: Festersen, S. Hrkac, S.B. Koops, C.T. Runge, B. Dane, T. Murphy, B.M. Magnussen, O.M. Tags: X-ray reflectivity liquid interfaces methods free-elecron laser synchrotron research papers Source Type: research

Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics
Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10 – 100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are explored via Gaussian and half-Gaussian spectra. Synchrotron undulator spectra represented...
Source: Journal of Synchrotron Radiation - February 16, 2018 Category: Physics Authors: Chen, S. Luo, S.-N. Tags: SAXS polychromatic size distribution undulator light source research papers Source Type: research

Energy-dependent dead-time correction in digital pulse processors applied to silicon drift detector's X-ray spectra
Dead-time effects in X-ray spectra taken with a digital pulse processor and a silicon drift detector were investigated when the number of events at the low-energy end of the spectrum was more than half of the total, at counting rates up to 56   kHz. It was found that dead-time losses in the spectra are energy dependent and an analytical correction for this effect, which takes into account pulse pile-up, is proposed. This and the usual models have been applied to experimental measurements, evaluating the dead-time fraction either from the calculations or using the value given by the detector acquisition system. The energy...
Source: Journal of Synchrotron Radiation - February 15, 2018 Category: Physics Authors: Barros, S.F. Vanin, V.R, Malafronte, A.A. Maidana, N.L. Martins, M.N. Tags: dead-time correction Si drift detector pile up research papers Source Type: research

Transmission of an X-ray beam through a two-dimensional photonic crystal and the Talbot effect
Results of computer simulations of the transmission of an X-ray beam through a two-dimensional photonic crystal as well as the propagation of an X-ray beam in free space behind the photonic crystal are reported. The photonic crystal consists of a square lattice of silicon cylinders of diameter 0.5   µ m. The amount of matter in the path of the X-ray beam rapidly decreases at the sides of the cylinder projections. Therefore the transmission is localized near the boundaries, and appears like a channeling effect. The iterative method of computer simulations is applied. This method is similar to the multi-slice method ...
Source: Journal of Synchrotron Radiation - February 15, 2018 Category: Physics Authors: Kohn, V.G. Tags: X-ray transmission two-dimensional photonic crystal Talbot effect computer simulations iterative algorithm research papers Source Type: research

High-energy-resolution diced spherical quartz analyzers for resonant inelastic X-ray scattering
A novel diced spherical quartz analyzer for use in resonant inelastic X-ray scattering (RIXS) is introduced, achieving an unprecedented energy resolution of 10.53   meV at the Ir L3 absorption edge (11.215   keV). In this work the fabrication process and the characterization of the analyzer are presented, and an example of a RIXS spectrum of magnetic excitations in a Sr3Ir2O7 sample is   shown. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 15, 2018 Category: Physics Authors: Said, A.H. Gog, T. Wieczorek, M. Huang, X. Casa, D. Kasman, E. Divan, R. Kim, J.H. Tags: RIXS high resolution analyzer inelastic X-ray quartz research papers Source Type: research

Nuclear resonance reflectivity from a [57Fe/Cr]30 multilayer with the Synchrotron M ö ssbauer Source
M ö ssbauer reflectivity spectra and nuclear resonance reflectivity (NRR) curves have been measured using the Synchrotron M ö ssbauer Source (SMS) for a [57Fe/Cr]30 periodic multilayer, characterized by the antiferromagnetic interlayer coupling between adjacent 57Fe layers. Specific features of the M ö ssbauer reflectivity spectra measured with π -polarized radiation of the SMS near the critical angle and at the `magnetic' maximum on the NRR curve are analyzed. The variation of the ratio of lines in the M ö ssbauer reflectivity spectra and the change of the intensity of the `magnetic' maximum under a...
Source: Journal of Synchrotron Radiation - February 15, 2018 Category: Physics Authors: Andreeva, M.A. Baulin, R.A. Chumakov, A.I. R ü ffer, R. Smirnov, G.V. Babanov, Y.A. Devyaterikov, D.I. Milyaev, M.A. Ponomarev, D.A. Romashev, L.N. Ustinov, V.V. Tags: magnetic multilayers antiferromagnetic interlayer coupling ö ssbauer spectroscopy nuclear resonance reflectivity Synchrotron M ssbauer Source research papers Source Type: research

FemtoMAX – an X-ray beamline for structural dynamics at the short-pulse facility of MAX IV
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 100   fs, which is on the timescale of molecular vibrations, and have wavelengths matching interatomic distances...
Source: Journal of Synchrotron Radiation - February 14, 2018 Category: Physics Authors: Enquist, H. Jurgilaitis, A. Jarnac, A. Bengtsson, Å .U.J. Burza, M. Curbis, F. Disch, C. Ekstr ö m, J.C. Harb, M. Isaksson, L. Kotur, M. Kroon, D. Lindau, F. Mansten, E. Nygaard, J. Persson, A.I.H. Pham, V.T. Rissi, M. Thorin, S. Tu, C.-M. Wall é n, E. Tags: structural dynamics pump – probe laser beamline ultrafast beamlines Source Type: research

Microbubbles containing gadolinium as contrast agents for both phase contrast and magnetic resonance imaging
In this study, the feasibility of using microbubbles containing gadolinium (MCG) as contrast agents for both phase contrast imaging (PCI) and magnetic resonance imaging (MRI) are investigated. MCG were made by encapsulating sulfur hexafluoride (SF6) gas with gadolinium and lyophilized powder. Absorption contrast imaging (ACI) and PCI of MCG were performed and compared in vitro. MCG were injected into the main portal trunk of living rats. PCI and MRI were performed at 2   min and 10   min after MCG injection, respectively. PCI exploited the differences in the refractive index and visibly showed the MCG, which were not d...
Source: Journal of Synchrotron Radiation - February 14, 2018 Category: Physics Authors: Tang, R. Yan, F. Yang, G.-Y. Chen, K.-M. Tags: phase contrast imaging microbubble gadolinium research papers Source Type: research

Quantum regime of a plasma-wave-pumped free-electron laser in the presence of an axial magnetic field
The quantum regime of a plasma-whistler-wave-pumped free-electron laser (FEL) in the presence of an axial-guide magnetic field is presented. By quantizing both the plasma whistler field and axial magnetic field, an N-particle three-dimensional Hamiltonian of quantum-FEL (QFEL) has been derived. Employing Heisenberg evolution equations and introducing a new collective operator which controls the vertical motion of electrons, a quantum dispersion relation of the plasma whistler wiggler has been obtained analytically. Numerical results indicate that, by increasing the intrinsic quantum momentum spread and/or increasing the ax...
Source: Journal of Synchrotron Radiation - February 14, 2018 Category: Physics Authors: Shirvani, H. Jafari, S. Tags: quantum-FEL plasma whistler wave Heisenberg evolution equations axial magnetic field strength research papers Source Type: research

Efficiency and coherence preservation studies of Be refractive lenses for XFELO application
Performance tests of parabolic beryllium refractive lenses, considered as X-ray focusing elements in the future X-ray free-electron laser oscillator (XFELO), are reported. Single and double refractive lenses were subject to X-ray tests, which included: surface profile, transmissivity measurements, imaging capabilities and wavefront distortion with grating interferometry. Optical metrology revealed that surface profiles were close to the design specification in terms of the figure and roughness. The transmissivity of the lenses is>94% at 8   keV and>98% at 14.4   and 18   keV. These values are close to the theor...
Source: Journal of Synchrotron Radiation - February 14, 2018 Category: Physics Authors: Kolodziej, T. Stoupin, S. Grizolli, W. Krzywinski, J. Shi, X. Kim, K.-J. Qian, J. Assoufid, L. Shvyd'ko, Yu. Tags: X-rays X-ray focusing X-ray optics refractive lenses research papers Source Type: research

Synchrotron Radiation and Free-Electron Lasers. Principles of Coherent X-ray Generation. By Kwang-Je Kim, Artur Braun and Zhirong Huang. Cambridge University Press, 2017. Pp. 298. Price GBP 89.99, hardback, ISBN 978-1107162617.
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 13, 2018 Category: Physics Authors: Helliwell, J.R. Tags: book review synchrotron radiation FEL radiation book reviews Source Type: research

Multi-channel in situ dynamic light scattering instrumentation enhancing biological small-angle X-ray scattering experiments at the PETRA III beamline P12
This study also shows and confirms that the newly designed sample compartment with attached DLS instrumentation does not disturb SAXS measurements. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 13, 2018 Category: Physics Authors: Falke, S. Dierks, K. Blanchet, C. Graewert, M. Cipriani, F. Meijers, R. Svergun, D. Betzel, C. Tags: in situ DLS multi-channel radius determination BioSAXS sample compartment sample quality assessment research papers Source Type: research

Anisotropy enhanced X-ray scattering from solvated transition metal complexes
Time-resolved X-ray scattering patterns from photoexcited molecules in solution are in many cases anisotropic at the ultrafast time scales accessible at X-ray free-electron lasers (XFELs). This anisotropy arises from the interaction of a linearly polarized UV – Vis pump laser pulse with the sample, which induces anisotropic structural changes that can be captured by femtosecond X-ray pulses. In this work, a method for quantitative analysis of the anisotropic scattering signal arising from an ensemble of molecules is described, and it is demonstrated how its use can enhance the structural sensitivity of the time-resol...
Source: Journal of Synchrotron Radiation - February 13, 2018 Category: Physics Authors: Biasin, E. van Driel, T.B. Levi, G. Laursen, M.G. Dohn, A.O. Moltke, A. Vester, P. Hansen, F.B.K. Kjaer, K.S. Harlang, T. Hartsock, R. Christensen, M. Gaffney, K.J. Henriksen, N.E. M ø ller, K.B. Haldrup, K. Nielsen, M.M. Tags: time-resolved anisotropic scattering orientational selection XFEL ultrafast molecular structure research papers Source Type: research

Enhancement of measurement accuracy of X-ray PIV in comparison with the micro-PIV technique
In this study, a new two-dimensional velocity field extraction technique is proposed to overcome technological limitations. To resolve the problem of finding a correction coefficient, the velocity field information obtained by X-ray PIV and micro-PIV techniques for disturbed flow in a concentric stenosis with 50% severity was quantitatively compared. Micro-PIV experiments were conducted for single-plane and summation images, which provide similar positional information of particles as X-ray images. The correction coefficient was obtained by establishing the relationship between velocity data obtained from summation images ...
Source: Journal of Synchrotron Radiation - February 13, 2018 Category: Physics Authors: Park, H. Jung, S.Y. Park, J.H. Kim, J.H. Lee, S.J. Tags: X-ray PIV micro-PIV stenosis biofluid flow correction coefficient research papers Source Type: research

Software for the data analysis of the arrival-timing monitor at SACLA
X-ray free-electron laser (XFEL) pulses from SPring-8 Å ngstrom Compact free-electron LAser (SACLA) with a temporal duration of (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 7, 2018 Category: Physics Authors: Nakajima, K. Joti, Y. Katayama, T. Owada, S. Togashi, T. Abe, T. Kameshima, T. Okada, K. Sugimoto, T. Yamaga, M. Hatsui, T. Yabashi, M. Tags: X-ray free-electron laser arrival-timing monitor data analysis software SACLA computer programs Source Type: research

X-ray position-sensitive duo-lateral diamond detectors at SOLEIL
The performance of a diamond X-ray beam position monitor is reported. This detector consists of an ionization solid-state chamber based on a thin single-crystal chemical-vapour-deposition diamond with position-sensitive resistive electrodes in a duo-lateral configuration. The detector's linearity, homogeneity and responsivity were studied on beamlines at Synchrotron SOLEIL with various beam sizes, intensities and energies. These measurements demonstrate the large and homogeneous (absorption variation of less than 0.7% over 500   µ m × 500   µ m) active area of the detector, with linear responses indep...
Source: Journal of Synchrotron Radiation - February 7, 2018 Category: Physics Authors: Desjardins, K. Bordessoule, M. Pomorski, M. Tags: X-ray beam position monitor XBPM PSD diamond detector noise analysis research papers Source Type: research

GAPD: a GPU-accelerated atom-based polychromatic diffraction simulation code
GAPD, a graphics-processing-unit (GPU)-accelerated atom-based polychromatic diffraction simulation code for direct, kinematics-based, simulations of X-ray/electron diffraction of large-scale atomic systems with mono-/polychromatic beams and arbitrary plane detector geometries, is presented. This code implements GPU parallel computation via both real- and reciprocal-space decompositions. With GAPD, direct simulations are performed of the reciprocal lattice node of ultralarge systems ( ∼ 5 billion atoms) and diffraction patterns of single-crystal and polycrystalline configurations with mono- and polychromatic X-ray beams...
Source: Journal of Synchrotron Radiation - February 6, 2018 Category: Physics Authors: E, J. C. Wang, L. Chen, S. Zhang, Y. Y. Luo, S. N. Tags: diffraction simulation reciprocal space mapping polychromatic beam parallel computing computer programs Source Type: research

M Ö NCH detector enables fast and low-dose free-propagation phase-contrast computed tomography of in situ mouse lungs
Due to the complexity of the underlying pathomechanism, in vivo mouse lung-disease models continue to be of great importance in preclinical respiratory research. Longitudinal studies following the cause of a disease or evaluating treatment efficacy are of particular interest but challenging due to the small size of the mouse lung and the fast breathing rate. Synchrotron-based in-line phase-contrast computed tomography imaging has been successfully applied in lung research in various applications, but mostly at dose levels that forbid longitudinal in vivo studies. Here, the novel charge-integrating hybrid detector M Ö ...
Source: Journal of Synchrotron Radiation - February 6, 2018 Category: Physics Authors: Dullin, C. Albers, J. Tromba, G. Andr ä , M. Ramilli, M. Bergamaschi, A. Tags: mouse-lung imaging low dose phase-contrast computed tomography charge-integration detector short communications Source Type: research

An electrochemical cell with sapphire windows for operando synchrotron X-ray powder diffraction and spectroscopy studies of high-power and high-voltage electrodes for metal-ion batteries
A new multi-purpose operando electrochemical cell was designed, constructed and tested on the Swiss – Norwegian Beamlines BM01 and BM31 at the European Synchrotron Radiation Facility. Single-crystal sapphire X-ray windows provide a good signal-to-noise ratio, excellent electrochemical contact because of the constant pressure between the electrodes, and perfect electrochemical stability at high potentials due to the inert and non-conductive nature of sapphire. Examination of the phase transformations in the Li1 – xFe0.5Mn0.5PO4 positive electrode (cathode) material at C/2 and 10C charge and discharge rates, and ...
Source: Journal of Synchrotron Radiation - February 6, 2018 Category: Physics Authors: Drozhzhin, O.A. Tereshchenko, I.V. Emerich, H. Antipov, E.V. Abakumov, A.M. Chernyshov, D. Tags: operando electrochemical cells metal-ion batteries X-ray diffraction X-ray absorption research papers Source Type: research

Polarization-independent absorption enhancement in a graphene square array with a cascaded grating structure
The polarization-independent enhanced absorption effect of graphene in the near-infrared range is investigated. This is achieved by placing a graphene square array on top of a dielectric square array backed by a two-dimensional multilayer grating. Total optical absorption in graphene can be attributed to critical coupling, which is achieved through the combined effect of guided-mode resonance with the dielectric square array and the photonic band gap with the two-dimensional multilayer grating. To reveal the physical origin of such a phenomenon, the electromagnetic field distributions for both polarizations are illustrated...
Source: Journal of Synchrotron Radiation - February 6, 2018 Category: Physics Authors: Wu, J. Tags: diffraction and gratings metamaterials graphene spectrum-selective absorption research papers Source Type: research

Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold
The durability of grazing- and normal-incidence optical coatings has been experimentally assessed under free-electron laser irradiation at various numbers of pulses up to 16 million shots and various fluence levels below 10% of the single-shot damage threshold. The experiment was performed at FLASH, the Free-electron LASer in Hamburg, using 13.5   nm extreme UV (EUV) radiation with 100   fs pulse duration. Polycrystalline ruthenium and amorphous carbon 50   nm thin films on silicon substrates were tested at total external reflection angles of 20 ° and 10 ° grazing incidence, respectively. Mo/Si periodical mul...
Source: Journal of Synchrotron Radiation - December 21, 2017 Category: Physics Authors: Makhotkin, I.A. Sobierajski, R. Chalupsk ý , J. Tiedtke, K. de Vries, G. St ö rmer, M. Scholze, F. Siewert, F. van de Kruijs, R.W.E. Milov, I. Louis, E. Jacyna, I. Jurek, M. Klinger, D. Nittler, L. Syryanyy, Y. Juha, L. H á jkov á , V. Vozda, V. Buria Tags: free-electron laser induced damage EUV optics thin films FELs research papers Source Type: research