DABAM: an open-source database of X-ray mirrors metrology
An open-source database containing metrology data for X-ray mirrors is presented. It makes available metrology data (mirror heights and slopes profiles) that can be used with simulation tools for calculating the effects of optical surface errors in the performances of an optical instrument, such as a synchrotron beamline. A typical case is the degradation of the intensity profile at the focal position in a beamline due to mirror surface errors. This database for metrology (DABAM) aims to provide to the users of simulation tools the data of real mirrors. The data included in the database are described in this paper, with de...
Source: Journal of Synchrotron Radiation - April 20, 2016 Category: Physics Authors: Sanchez del Rio, M.Bianchi, D.Cocco, D.Glass, M.Idir, M.Metz, J.Raimondi, L.Rebuffi, L.Reininger, R.Shi, X.Siewert, F.Spielmann-Jaeggi, S.Takacs, P.Tomasset, M.Tonnessen, T.Vivo, A.Yashchuk, V. Tags: X-ray mirror metrology database Python statistics research papers Source Type: research

Multiple scattering in grazing-incidence X-ray diffraction: impact on lattice-constant determination in thin films
This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to...
Source: Journal of Synchrotron Radiation - April 20, 2016 Category: Physics Authors: Resel, R.Bainschab, M.Pichler, A.Dingemans, T.Simbrunner, C.Stangl, J.Salzmann, I. Tags: organic thin films X-ray scattering grazing-incidence diffraction surface reflection X-ray refraction grazing-incidence X-ray diffraction refraction correction research papers Source Type: research

A sample cell for in situ electric-field-dependent structural characterization and macroscopic strain measurements
When studying electro-mechanical materials, observing the structural changes during the actuation process is necessary for gaining a complete picture of the structure–property relationship as certain mechanisms may be meta-stable during actuation. In situ diffraction methods offer a powerful and direct means of quantifying the structural contributions to the macroscopic strain of these materials. Here, a sample cell is demonstrated capable of measuring the structural variations of electro-mechanical materials under applied electric potentials up to 10 kV. The cell is designed for use with X-ray scattering technique...
Source: Journal of Synchrotron Radiation - April 20, 2016 Category: Physics Authors: Hossain, M.J.Wang, L.Wang, Z.Khansur, N.H.Hinterstein, M.Kimpton, J.A.Daniels, J.E. Tags: X-ray diffraction strain electro-ceramics piezoelectrics ferroelectrics research papers Source Type: research

Spectrum splitting for fast polarization switching of   undulator radiation
A simple scheme to quickly switch the polarity of circular radiation is proposed, which is based on spectrum splitting of undulator radiation. In this scheme, two helical undulators with opposite helicities are placed tandem in one straight section, both of which are divided into several segments. The optical phases between segments are tuned so that light waves from one of the two undulators are out of phase, while those from the other are in phase. Then the radiation spectrum of the former is split and the intensity at the fundamental photon energy vanishes. As a consequence, the monochromated photon beam at the fundamen...
Source: Journal of Synchrotron Radiation - April 19, 2016 Category: Physics Authors: Kinjo, R. Tanaka, T. Tags: undulator radiation fast polarization switching spectrum-splitting scheme research papers Source Type: research

Submillisecond X-ray photon correlation spectroscopy   from a pixel array detector with fast   dual gating and no readout dead-time
Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8   kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 19, 2016 Category: Physics Authors: Zhang, Q. Dufresne, E.M. Grybos, P. Kmon, P. Maj, P. Narayanan, S. Deptuch, G.W. Szczygiel, R. Sandy, A. Tags: pixel array detector (PAD) high frame rate photon counting two counters X-ray photon correlation spectroscopy (XPCS) small-angle X-ray scattering (SAXS) research papers Source Type: research

Sapphire hard X-ray Fabry – Perot resonators for synchrotron experiments
Hard X-ray Fabry – Perot resonators (FPRs) made from sapphire crystals were constructed and characterized. The FPRs consisted of two crystal plates, part of a monolithic crystal structure of Al2O3, acting as a pair of mirrors, for the backward reflection (0   0   0   30) of hard X-rays at 14.3147   keV. The dimensional accuracy during manufacturing and the defect density in the crystal in relation to the resonance efficiency of sapphire FPRs were analyzed from a theoretical standpoint based on X-ray cavity resonance and measurements using scanning electron microscopic and X-ray topographic techniques for crys...
Source: Journal of Synchrotron Radiation - April 19, 2016 Category: Physics Authors: Tsai, Y.-W. Wu, Y.-H. Chang, Y.-Y. Liu, W.-C. Liu, H.-L. Chu, C.-H. Chen, P.-C. Lin, P.-T. Fu, C.-C. Chang, S.-L. Tags: sapphire Fabry – Perot resonator coherent X-rays backward diffraction dynamical diffraction high-resolution monochromator research papers Source Type: research

Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time
Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 18, 2016 Category: Physics Authors: Zhang, Q.Dufresne, E.M.Grybos, P.Kmon, P.Maj, P.Narayanan, S.Deptuch, G.W.Szczygiel, R.Sandy, A. Tags: pixel array detector (PAD) high frame rate photon counting two counters X-ray photon correlation spectroscopy (XPCS) small-angle X-ray scattering (SAXS) research papers Source Type: research

Spectrum splitting for fast polarization switching of undulator radiation
A simple scheme to quickly switch the polarity of circular radiation is proposed, which is based on spectrum splitting of undulator radiation. In this scheme, two helical undulators with opposite helicities are placed tandem in one straight section, both of which are divided into several segments. The optical phases between segments are tuned so that light waves from one of the two undulators are out of phase, while those from the other are in phase. Then the radiation spectrum of the former is split and the intensity at the fundamental photon energy vanishes. As a consequence, the monochromated photon beam at the fundamen...
Source: Journal of Synchrotron Radiation - April 18, 2016 Category: Physics Authors: Kinjo, R.Tanaka, T. Tags: undulator radiation fast polarization switching spectrum-splitting scheme research papers Source Type: research

Sapphire hard X-ray Fabry–Perot resonators for synchrotron experiments
Hard X-ray Fabry–Perot resonators (FPRs) made from sapphire crystals were constructed and characterized. The FPRs consisted of two crystal plates, part of a monolithic crystal structure of Al2O3, acting as a pair of mirrors, for the backward reflection (0 0 0 30) of hard X-rays at 14.3147 keV. The dimensional accuracy during manufacturing and the defect density in the crystal in relation to the resonance efficiency of sapphire FPRs were analyzed from a theoretical standpoint based on X-ray cavity resonance and measurements using scanning electron microscopic and X-ray topographic techniques for crystal defect...
Source: Journal of Synchrotron Radiation - April 18, 2016 Category: Physics Authors: Tsai, Y.-W.Wu, Y.-H.Chang, Y.-Y.Liu, W.-C.Liu, H.-L.Chu, C.-H.Chen, P.-C.Lin, P.-T.Fu, C.-C.Chang, S.-L. Tags: sapphire Fabry – Perot resonator coherent X-rays backward diffraction dynamical diffraction high-resolution monochromator research papers Source Type: research

A Johann-type X-ray emission spectrometer at   the   Rossendorf beamline
This paper gives a detailed description, including equations, of the Johann-type X-ray emission spectrometer which has been recently installed and tested at the Rossendorf beamline (ROBL) of the European Synchrotron Radiation Facility. The spectrometer consists of a single spherically bent crystal analyzer and an avalanche photodiode detector positioned on the vertical Rowland cycle of 1   m diameter. The hard X-ray emission spectrometer ( ∼ 3.5 – 25   keV) operates at atmospheric pressure and covers the Bragg angles of 65 ° – 89 ° . The instrument has been tested at high and intermediate incide...
Source: Journal of Synchrotron Radiation - April 16, 2016 Category: Physics Authors: Kvashnina, K.O. Scheinost, A.C. Tags: X-ray emission spectrometer Johann geometry XANES HERFD XES RIXS actinides beamlines Source Type: research

Amyloid- β plaque deposition measured using propagation-based X-ray phase contrast CT imaging
Amyloid beta accumulation into insoluble plaques (A β p) is known to play a significant role in the pathological process in Alzheimer's disease (AD). The presence of A β p is also one of the neuropathological hallmarks for the disease. AD final diagnosis is generally acknowledged after the evaluation of A β p deposition in the brain. Insoluble A β p accumulation may also concur to cause AD as postulated in the so-called amyloid hypothesis. Therefore, the visualization, evaluation and quantification of A β p are nowadays the keys for a better understanding of the disease, which may point to a possib...
Source: Journal of Synchrotron Radiation - April 16, 2016 Category: Physics Authors: Astolfo, A. Lathuili è re, A. Laversenne, V. Schneider, B. Stampanoni, M. Tags: phase contrast X-ray CT brain imaging amyloid plaques Alzheimer's disease research papers Source Type: research

A Johann-type X-ray emission spectrometer at the Rossendorf beamline
This paper gives a detailed description, including equations, of the Johann-type X-ray emission spectrometer which has been recently installed and tested at the Rossendorf beamline (ROBL) of the European Synchrotron Radiation Facility. The spectrometer consists of a single spherically bent crystal analyzer and an avalanche photodiode detector positioned on the vertical Rowland cycle of 1 m diameter. The hard X-ray emission spectrometer (∼3.5–25 keV) operates at atmospheric pressure and covers the Bragg angles of 65°–89°. The instrument has been tested at high and intermediate incident energies, ...
Source: Journal of Synchrotron Radiation - April 16, 2016 Category: Physics Authors: Kvashnina, K.O.Scheinost, A.C. Tags: X-ray emission spectrometer Johann geometry XANES HERFD XES RIXS actinides beamlines Source Type: research

Amyloid-β plaque deposition measured using propagation-based X-ray phase contrast CT imaging
Amyloid beta accumulation into insoluble plaques (Aβp) is known to play a significant role in the pathological process in Alzheimer's disease (AD). The presence of Aβp is also one of the neuropathological hallmarks for the disease. AD final diagnosis is generally acknowledged after the evaluation of Aβp deposition in the brain. Insoluble Aβp accumulation may also concur to cause AD as postulated in the so-called amyloid hypothesis. Therefore, the visualization, evaluation and quantification of Aβp are nowadays the keys for a better understanding of the disease, which may point to a possible cure fo...
Source: Journal of Synchrotron Radiation - April 16, 2016 Category: Physics Authors: Astolfo, A.Lathuilière, A.Laversenne, V.Schneider, B.Stampanoni, M. Tags: phase contrast X-ray CT brain imaging amyloid plaques Alzheimer's disease research papers Source Type: research

Implementation of ultrafast X-ray diffraction at the 1W2B wiggler beamline of Beijing Synchrotron Radiation Facility
The implementation of a laser pump/X-ray probe scheme for performing picosecond-resolution X-ray diffraction at the 1W2B wiggler beamline at Beijing Synchrotron Radiation Facility is reported. With the hybrid fill pattern in top-up mode, a pixel array X-ray detector was optimized to gate out the signal from the singlet bunch with interval 85 ns from the bunch train. The singlet pulse intensity is ∼2.5 × 106 photons pulse−1 at 10 keV. The laser pulse is synchronized to this singlet bunch at a 1 kHz repetition rate. A polycapillary X-ray lens was used for secondary focusing to obtain a 72 µm...
Source: Journal of Synchrotron Radiation - April 14, 2016 Category: Physics Authors: Sun, D.-R.Xu, G.-L.Zhang, B.-B.Du, X.-Y.Wang, H.Li, Q.-J.Zhou, Y.-F.Li, Z.-J.Zhang, Y.He, J.Yue, J.-H.Lei, G.Tao, Y. Tags: laser pump/X-ray probe ultrafast X-ray diffraction photo-induced strain beamlines Source Type: research

XAS spectroelectrochemistry: reliable measurement of X-ray absorption spectra from redox manipulated solutions at room temperature
The design and operation of a low-volume spectroelectrochemical cell for X-ray absorption spectroscopy (XAS) of solutions at room temperature is described. Fluorescence XAS measurements are obtained from samples contained in the void space of a 50 µL reticulated vitreous carbon (sponge) working electrode. Both rapid electrosynthesis and control of the effects of photoreduction are achieved by control over the flow properties of the solution through the working electrode, where a good balance between the rate of consumption of sample and the minimization of decomposition was obtained by pulsing the flow of the solut...
Source: Journal of Synchrotron Radiation - April 14, 2016 Category: Physics Authors: Best, S.P.Levina, A.Glover, C.Johannessen, B.Kappen, P.Lay, P.A. Tags: XAS XANES spectroelectrochemistry metalloproteins trioxalatoferrate(III) research papers Source Type: research

Time- and spatial-resolved XAFS spectroscopy in a single shot: new analytical possibilities for in situ material characterization
A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ–2θ geometry....
Source: Journal of Synchrotron Radiation - April 14, 2016 Category: Physics Authors: Buzanich, A..GRadtke, M.Reinholz, U.Riesemeier, H.Emmerling, F. Tags: single-shot XAFS time resolution spatial resolution divergent XAFS research papers Source Type: research

Analysis of the halo background in femtosecond slicing experiments
The slicing facility FemtoSpeX at BESSY II offers unique opportunities to study photo-induced dynamics on femtosecond time scales by means of X-ray magnetic circular dichroism, resonant and non-resonant X-ray diffraction, and X-ray absorption spectroscopy experiments in the soft X-ray regime. Besides femtosecond X-ray pulses, slicing sources inherently also produce a so-called `halo' background with a different time structure, polarization and pointing. Here a detailed experimental characterization of the halo radiation is presented, and a method is demonstrated for its correct and unambiguous removal from femtosecond ti...
Source: Journal of Synchrotron Radiation - April 14, 2016 Category: Physics Authors: Schick, D.Le Guyader, L.Pontius, N.Radu, I.Kachel, T.Mitzner, R.Zeschke, T.Schüßler-Langeheine, C.Föhlisch, A.Holldack, K. Tags: femtosecond slicing halo pump – probe XMCD X-ray scattering research papers Source Type: research

Using synchrotron radiation inline phase-contrast imaging computed tomography to visualize three-dimensional printed hybrid constructs for cartilage tissue engineering
Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This...
Source: Journal of Synchrotron Radiation - April 14, 2016 Category: Physics Authors: Olubamiji, A.D.Izadifar, Z.Zhu, N.Chang, T.Chen, X.Eames, B.F. Tags: SR-inline-PCI-CT sample-to-detector distance hybrid constructs cartilage tissue engineering research papers Source Type: research

Synchrotron X-ray phase contrast imaging of leaf venation in soybean (Glycine max) after exclusion of solar UV (280–400 nm) radiation
The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280–315 nm) or UVAB (280–400 nm), or transmitted all the ambient solar UV (280–400 nm) radiation (filter control). Qualitative obs...
Source: Journal of Synchrotron Radiation - April 12, 2016 Category: Physics Authors: Fatima, A.Kataria, S.Guruprasad, K.N.Agrawal, A.K.Singh, B.Sarkar, P.S.Shripathi, T.Kashyap, Y.Sinha, A. Tags: phase contrast imaging (PCI) micro-imaging soybean UV exclusion research papers Source Type: research

MMX-I: data-processing software for multimodal X-ray imaging and tomography
A new multi-platform freeware has been developed for the processing and reconstruction of scanning multi-technique X-ray imaging and tomography datasets. The software platform aims to treat different scanning imaging techniques: X-ray fluorescence, phase, absorption and dark field and any of their combinations, thus providing an easy-to-use data processing tool for the X-ray imaging user community. A dedicated data input stream copes with the input and management of large datasets (several hundred GB) collected during a typical multi-technique fast scan at the Nanoscopium beamline and even on a standard PC. To the authors'...
Source: Journal of Synchrotron Radiation - April 12, 2016 Category: Physics Authors: Bergamaschi, A.Medjoubi, K.Messaoudi, C.Marco, S.Somogyi, A. Tags: scanning multimodal X-ray imaging scanning X-ray tomography tomographic reconstruction phase retrieval research papers Source Type: research

Simulation of FEL pulse length calculation with THz streaking method
Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pump–probe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostic...
Source: Journal of Synchrotron Radiation - April 2, 2016 Category: Physics Authors: Gorgisyan, I.Ischebeck, R.Prat, E.Reiche, S.Rivkin, L.Juranić, P. Tags: simulation free-electron laser femtosecond metrology terahertz streaking hard X-rays time-of-flight spectrometer research papers Source Type: research

Versatile variable temperature insert at the DEIMOS beamline for in situ electrical transport measurements
The design and the first experiments are described of a versatile cryogenic insert used for its electrical transport capabilities. The insert is designed for the cryomagnet installed on the DEIMOS beamline at the SOLEIL synchrotron dedicated to magnetic characterizations through X-ray absorption spectroscopy (XAS) measurements. This development was spurred by the multifunctional properties of novel materials such as multiferroics, in which, for example, the magnetic and electrical orders are intertwined and may be probed using XAS. The insert thus enables XAS to in situ probe this interplay. The implementation of redundant...
Source: Journal of Synchrotron Radiation - April 2, 2016 Category: Physics Authors: Joly, L.Muller, B.Sternitzky, E.Faullumel, J.-G.Boulard, A.Otero, E.Choueikani, F.Kappler, J.-P.Studniarek, M.Bowen, M.Ohresser, P. Tags: cryogenic insert X-ray absorption spectroscopy magnetic and electrical orders multiferroics research papers Source Type: research

Polarized hard X-ray photoemission system with micro-positioning technique for probing ground-state symmetry of strongly correlated materials
An angle-resolved linearly polarized hard X-ray photoemission spectroscopy (HAXPES) system has been developed to study the ground-state symmetry of strongly correlated materials. The linear polarization of the incoming X-ray beam is switched by a transmission-type phase retarder composed of two diamond (100) crystals. The best value of the degree of linear polarization was found to be −0.96, containing a vertical polarization component of 98%. A newly developed low-temperature two-axis manipulator enables easy polar and azimuthal rotations to select the detection direction of photoelectrons. The lowest temperature ac...
Source: Journal of Synchrotron Radiation - April 1, 2016 Category: Physics Authors: Fujiwara, H.Naimen, S.Higashiya, A.Kanai, Y.Yomosa, H.Yamagami, K.Kiss, T.Kadono, T.Imada, S.Yamasaki, A.Takase, K.Otsuka, S.Shimizu, T.Shingubara, S.Suga, S.Yabashi, M.Tamasaku, K.Ishikawa, T.Sekiyama, A. Tags: hard X-ray photoemission linear dichroism strongly correlated electron systems phase retarder micro-focused X-rays sample monitoring system low-temperature double-axis manipulator research papers Source Type: research

Temperature-driven directional coalescence of silver nanoparticles
This study is of importance not only in terms of its fundamental academic interest but also in terms of the thermal stability of silver nanoparticles. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 1, 2016 Category: Physics Authors: Yan, S.Sun, D.Gong, Y.Tan, Y.Xing, X.Mo, G.Chen, Z.Cai, Q.Li, Z.Yu, H.Wu, Z. Tags: silver nanoparticles SAXS XRD coalescence nanocrystal research papers Source Type: research

Dynamic crystal rotation resolved by high-speed synchrotron X-ray Laue diffraction
Dynamic compression experiments are performed on single-crystal Si under split Hopkinson pressure bar loading, together with simultaneous high-speed (250–350 ns resolution) synchrotron X-ray Laue diffraction and phase-contrast imaging. A methodology is presented which determines crystal rotation parameters, i.e. instantaneous rotation axes and angles, from two unindexed Laue diffraction spots. Two-dimensional translation is obtained from dynamic imaging by a single camera. High-speed motion of crystals, including translation and rotation, can be tracked in real time via simultaneous imaging and diffraction. (Source...
Source: Journal of Synchrotron Radiation - March 30, 2016 Category: Physics Authors: Huang, J.W.E, J.C.Huang, J.Y.Sun, T.Fezzaa, K.Luo, S.N. Tags: synchrotron X-ray Laue diffraction crystal rotation research papers Source Type: research

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources
The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated again...
Source: Journal of Synchrotron Radiation - March 24, 2016 Category: Physics Authors: Rutherford, M.E.Chapman, D.J.White, T.G.Drakopoulos, M.Rack, A.Eakins, D.E. Tags: dynamic imaging shock compression time-resolved X-ray scintillator research papers Source Type: research

Extraction of local coordination structure in a low-concentration uranyl system by XANES
Obtaining structural information of uranyl species at an atomic/molecular scale is a critical step to control and predict their physical and chemical properties. To obtain such information, experimental and theoretical L3-edge X-ray absorption near-edge structure (XANES) spectra of uranium were studied systematically for uranyl complexes. It was demonstrated that the bond lengths (R) in the uranyl species and relative energy positions (ΔE) of the XANES were determined as follows: ΔE1 = 168.3/R(U—Oax)2 − 38.5 (for the axial plane) and ΔE2 = 428.4/R(U—Oeq)2 − 37.1 (for the equatorial...
Source: Journal of Synchrotron Radiation - March 24, 2016 Category: Physics Authors: Zhang, L.Zhou, J.Zhang, J.Su, J.Zhang, S.Chen, N.Jia, Y.Li, J.Wang, Y.Wang, J.-Q. Tags: uranyl speciation XANES local coordination structure multiple-scattering calculation EXAFS research papers Source Type: research

A new multipurpose diffractometer PILATUS@SNBL
The diffraction beamline BM01A at the European Synchrotron Radiation Facility (CRG Swiss–Norwegian beamlines) has been successfully operational for 20 years. Recently, a new multifunctional diffractometer based on the Dectris Pilatus 2M detector has been constructed, commissioned and offered to users. The diffractometer combines a fast and low-noise area detector, which can be tilted and moved horizontally and vertically, together with flexible goniometry for sample positioning and orientation. The diffractometer is controlled by a user-friendly and GUI-based software Pylatus which is also used to control various aux...
Source: Journal of Synchrotron Radiation - March 23, 2016 Category: Physics Authors: Dyadkin, V.Pattison, P.Dmitriev, V.Chernyshov, D. Tags: data processing area detector diffractometry beamlines Source Type: research

A setup for synchrotron-radiation-induced total reflection X-ray fluorescence and X-ray absorption near-edge structure recently commissioned at BESSY II BAMline
An automatic sample changer chamber for total reflection X-ray fluorescence (TXRF) and X-ray absorption near-edge structure (XANES) analysis in TXRF geometry was successfully set up at the BAMline at BESSY II. TXRF and TXRF-XANES are valuable tools for elemental determination and speciation, especially where sample amounts are limited ( (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - March 23, 2016 Category: Physics Authors: Fittschen, U.Guilherme, A.Böttger, S.Rosenberg, D.Menzel, M.Jansen, W.Busker, M.Gotlib, Z.P.Radtke, M.Riesemeier, H.Wobrauschek, P.Streli, C. Tags: TXRF TXRF-XANES sample changer BAMline Re-XANES short communications Source Type: research

Synchrotron-radiation-based X-ray micro-computed tomography reveals dental bur debris under dental composite restorations
Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material. Non-destructive micro-computed tomography using the BioMedical Imaging & Therapy facility 05ID-2 beamlin...
Source: Journal of Synchrotron Radiation - March 22, 2016 Category: Physics Authors: Hedayat, A.Nagy, N.Packota, G.Monteith, J.Allen, D.Wysokinski, T.Zhu, N. Tags: in-line phase contrast imaging micro-computed tomography dental bur debris composite resin dental filling tungsten carbide – cobalt dentinal tubule dentinal fluid research papers Source Type: research

Current events
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 26, 2016 Category: Physics Authors: , Tags: current events Source Type: research

Hybrid pixel array detectors enter the low noise regime
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 25, 2016 Category: Physics Authors: Graafsma, H. Tags: detectors hybrid pixel array detectors HPADs low-noise detectors scientific commentaries Source Type: research

Optimization of the design for beamline with fast polarization switching elliptically polarized undulators
Fast switching of X-ray polarization with a lock-in amplifier is a good method for acquiring weak signals from background noise for X-ray magnetic circular dichroism (XMCD) experiments. The usual way to obtain a beam with fast polarization switching is to use two series of elliptically polarized undulators (tandem twin EPUs). The two EPUs generate two individual beams. Each beam has a different polarization and is fast switched into the beamline. It is very important to ensure that the energy resolution, the flux and the spot size at the sample of the two beams are equal in XMCD experiments. However, it is difficult in bea...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Cao, J.Wang, Y.Zou, Y.Zhang, X.Wu, Y.Tai, R. Tags: soft X-ray magnetic circular dichroism beamline fast polarization switching tandem twin elliptically polarized undulators energy resolution research papers Source Type: research

A modified discrete algebraic reconstruction technique for multiple grey image reconstruction for limited angle range tomography
The `missing wedge', which is due to a restricted rotation range, is a major challenge for quantitative analysis of an object using tomography. With prior knowledge of the grey levels, the discrete algebraic reconstruction technique (DART) is able to reconstruct objects accurately with projections in a limited angle range. However, the quality of the reconstructions declines as the number of grey levels increases. In this paper, a modified DART (MDART) was proposed, in which each independent region of homogeneous material was chosen as a research object, instead of the grey values. The grey values of each discrete region w...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Liang, Z.Guan, Y.Liu, G.Chen, X.Li, F.Guo, P.Tian, Y. Tags: modified discrete algebraic reconstruction technique (MDART) multiple grey image image reconstruction limited-angle range research papers Source Type: research

The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32
A new high-field magnet endstation for X-ray magnetic dichroism experiments has been installed and commissioned at the ESRF soft X-ray beamline ID32. The magnet consists of two split-pairs of superconducting coils which can generate up to 9 T along the beam and up to 4 T orthogonal to the beam. It is connected to a cluster of ultra-high-vacuum chambers that offer a comprehensive set of surface preparation and characterization techniques. The endstation and the beam properties have been designed to provide optimum experimental conditions for X-ray magnetic linear and circular dichroism experiments in the soft X-ray rang...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Kummer, K.Fondacaro, A.Jimenez, E.Velez-Fort, E.Amorese, A.Aspbury, M.Yakhou-Harris, F.van der Linden, P.Brookes, N.B. Tags: high-field magnet endstation ID32 ESRF sample preparation XMCD XMLD research papers Source Type: research

FDMX: extended X-ray absorption fine structure calculations using the finite difference method
A new theoretical approach and computational package, FDMX, for general calculations of X-ray absorption fine structure (XAFS) over an extended energy range within a full-potential model is presented. The final-state photoelectron wavefunction is calculated over an energy-dependent spatial mesh, allowing for a complete representation of all scattering paths. The electronic potentials and corresponding wavefunctions are subject to constraints based on physicality and self-consistency, allowing for accurate absorption cross sections in the near-edge region, while higher-energy results are enabled by the implementation of eff...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Bourke, J.D.Chantler, C.T.Joly, Y. Tags: X-ray absorption finite difference methods fine structure XAFS FDMNES FDMX research papers Source Type: research

Novel micro-reactor flow cell for investigation of model catalysts using in situ grazing-incidence X-ray scattering
The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing-incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments at synchrotron facil...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Kehres, J.Pedersen, T.Masini, F.Andreasen, J.W.Nielsen, M.M.Diaz, A.Nielsen, J.H.Hansen, O.Chorkendorff, I. Tags: in situ GISAXS GIWAXS micro-reactor research papers Source Type: research

Analysis and control of the photon beam position at PLS-II
At third-generation light sources, the photon beam position stability is a critical issue for user experiments. In general, photon beam position monitors are developed to detect the real photon beam position, and the position is controlled by a feedback system in order to maintain the reference photon beam position. At Pohang Light Source II, a photon beam position stability of less than 1 µm r.m.s. was achieved for a user service period in the beamline, where the photon beam position monitor is installed. Nevertheless, a detailed analysis of the photon beam position data was necessary in order to ensure the perfor...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Ko, J.Kim, I.-Y.Kim, C.Kim, D.-T.Huang, J.-Y.Shin, S. Tags: photon beam position monitor stability SVD analysis research papers Source Type: research

Densitometry and temperature measurement of combustion gas by X-ray Compton scattering
Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Sakurai, H.Kawahara, N.Itou, M.Tomita, E.Suzuki, K.Sakurai, Y. Tags: Compton scattering laminar flame imaging temperature combustion reaction research papers Source Type: research

Compound refractive lenses as prefocusing optics for X-ray FEL radiation
The performance of X-ray free-electron laser beamlines may be limited by the angular aperture. Compound refractive lenses (CRLs) can be employed to prefocus the X-ray beam, thereby increasing the beamline transmission. A prefocusing CRL was implemented in the X-ray transport of the Matter under Extreme Conditions Instrument at the Linac Coherent Light Source. A significant improvement in the beamline transmission was calculated over the 3–10 keV photon energy range. At 5 keV, the relative X-ray intensity was measured and a factor of four increase was seen in the beamline transmission. The X-ray focus was also det...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Heimann, P.MacDonald, M.Nagler, B.Lee, H.J.Galtier, E.Arnold, B.Xing, Z. Tags: compound refractive lens X-ray free-electron laser X-ray optics research papers Source Type: research

Observation of scissors modes in solid state systems with a SQUID
The occurrence of scissors modes in crystals that have deformed ions in their unit cells was predicted some time ago. The theoretical value of their energy is rather uncertain, however, ranging between ten and a few tens of eV, with the corresponding widths of 10−7 to 10−6 eV. Their observation by resonance fluorescence experiments therefore requires a photon spectrometer covering a wide energy range with a very high resolving power. Here, a new experiment is proposed and discussed in which such difficulties are overcome by measuring with a superconducting quantum interference device (SQUID) the variation of ...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Hatada, K.Hayakawa, K.Palumbo, F.Marcelli, A. Tags: rotor model of deformed ions scissors modes SQUID collective magnetic excitations research papers Source Type: research

Rapid in situ X-ray position stabilization via extremum seeking feedback
X-ray beam stability is crucial for acquiring high-quality data at synchrotron beamline facilities. When the X-ray beam and defining apertures are of similar dimensions, small misalignments driven by position instabilities give rise to large intensity fluctuations. This problem is solved using extremum seeking feedback control (ESFC) for in situ vertical beam position stabilization. In this setup, the intensity spatial gradient required for ESFC is determined by phase comparison of intensity oscillations downstream from the sample with pre-existing vertical beam oscillations. This approach compensates for vertical position...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Zohar, S.Venugopalan, N.Kissick, D.Becker, M.Xu, S.Makarov, O.Stepanov, S.Ogata, C.Sanishvili, R.Fischetti, R.F. Tags: extremum seeking stabilization feedback X-rays research papers Source Type: research

Temperature-dependent EXAFS study of the local structure and lattice dynamics in cubic Y2O3
The local structure and lattice dynamics in cubic Y2O3 were studied at the Y K-edge by X-ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X-ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ∼6 Å and to validate two force-field models. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Jonane, I.Lazdins, K.Timoshenko, J.Kuzmin, A.Purans, J.Vladimirov, P.Gräning, T.Hoffmann, J. Tags: EXAFS molecular dynamics reverse Monte Carlo evolutionary algorithm yttria research papers Source Type: research

The LUCIA beamline at SOLEIL
Commissioned in May 2004 on the SLS machine, the LUCIA beamline was moved to the synchrotron SOLEIL during the summer of 2008. To take advantage of this new setting several changes to its design were introduced. Here, a review of the various improvements of the mechanics and, mostly, of the optics is given. Described in detail are the results of a new multilayer grating monochromator implemented on the Kohzu vessel already holding the two-crystal set-up. It consists of a grating grooved onto a multilayer (replacing the first crystal) associated to a multilayer (as a second crystal). It allows a shift of the low-energy limi...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Vantelon, D.Trcera, N.Roy, D.Moreno, T.Mailly, D.Guilet, S.Metchalkov, E.Delmotte, F.Lassalle, B.Lagarde, P.Flank, A.-M. Tags: X-ray spectrocopy beamline multilayer grating monochromator microspectroscopy beamlines Source Type: research

Protein crystallography beamline (PX-BL21) at Indus-2 synchrotron
The protein crystallography beamline (PX-BL21), installed at the 1.5 T bending-magnet port at the Indian synchrotron (Indus-2), is now available to users. The beamline can be used for X-ray diffraction measurements on a single crystal of macromolecules such as proteins, nucleic acids and their complexes. PX-BL21 has a working energy range of 5–20 keV for accessing the absorption edges of heavy elements commonly used for phasing. A double-crystal monochromator [Si(111) and Si(220)] and a pair of rhodium-coated X-ray mirrors are used for beam monochromatization and manipulation, respectively. This beamline is equip...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Kumar, A.Ghosh, B.Poswal, H.K.Pandey, K.K.JagannathHosur, M.V.Dwivedi, A.Makde, R.D.Sharma, S.M. Tags: protein crystallography beamline bending magnet Indus-2 beamlines Source Type: research

Perspectives and limitations of symmetric X-ray Bragg reflections for inspecting polytypism in nanowires
X-ray diffraction, possibly time-resolved during growth or annealing, is an important technique for the investigation of polytypism in free-standing nanowires. A major advantage of the X-ray diffraction approach for adequately chosen beam conditions is its high statistical significance in comparison with transmission electron microscopy. In this manuscript the interpretation of such X-ray intensity distribution is discussed, and is shown to be non-trivial and non-unique given measurements of the [111]c or [333]c reflection of polytypic nanowires grown in the (111)c direction. In particular, the diffracted intensity distrib...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Köhl, M.Schroth, P.Baumbach, T. Tags: diffraction nanowires GaAs polytypism research papers Source Type: research

Visualization of microvasculature and thrombi by X-ray phase-contrast computed tomography in hepatocellular carcinoma
In conclusion, PCCT can clearly show the three-dimensional subtle structures of HCC that cannot be detected by conventional absorption-based computed tomography and provides a new method for the imageology of HCC. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Jian, J.Yang, H.Zhao, X.Xuan, R.Zhang, Y.Li, D.Hu, C. Tags: hepatocellular carcinoma (HCC) microvasculature thrombus phase-contrast computed tomography (PCCT) research papers Source Type: research

In situ synchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF
The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performing in situ XRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstru...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: El Ashmawy, M.Amer, H.Abdellatief, M. Tags: synchrotron diffraction thermoluminescence dislocation density kinetics nanocrystalline microstructure research papers Source Type: research

Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers
Inelastic X-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25 nm−1 spectral and momentum-transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02 nm−1 are required to close the gap in energy–momentum space between high- and low-frequency probes. It is shown that this goal can be achieved by further optimizing the X-ray optics and by increasing the spectral flux of the incident X-ray pulses. UHRIX performs best at...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Chubar, O.Geloni, G.Kocharyan, V.Madsen, A.Saldin, E.Serkez, S.Shvyd'ko, Y.Sutter, J. Tags: inelastic X-ray scattering X-ray free-electron laser X-ray optics research papers Source Type: research

Studying solutions at high shear rates: a dedicated microfluidics setup
The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s−1. These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates. ...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Wieland, D.C.F.Garamus, V.M.Zander, T.Krywka, C.Wang, M.Dedinaite, A.Claesson, P.M.Willumeit-Römer, R. Tags: shear complex solutions small-angle X-ray scattering (SAXS) microfluidics lysozyme aggregation rheology protein interaction beamline setup research papers Source Type: research