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

Non-negative matrix factorization for the near real-time interpretation of absorption effects in elemental distribution images acquired by X-ray fluorescence imaging
Elemental distribution images acquired by imaging X-ray fluorescence analysis can contain high degrees of redundancy and weakly discernible correlations. In this article near real-time non-negative matrix factorization (NMF) is described for the analysis of a number of data sets acquired from samples of a bi-modal α+β Ti-6Al-6V-2Sn alloy. NMF was used for the first time to reveal absorption artefacts in the elemental distribution images of the samples, where two phases of the alloy, namely α and β, were in superposition. The findings and interpretation of the NMF results were confirmed by Monte Carlo ...
Source: Journal of Synchrotron Radiation - February 11, 2016 Category: Physics Authors: Alfeld, M.Wahabzada, M.Bauckhage, C.Kersting, K.Wellenreuther, G.Barriobero-Vila, P.Requena, G.Boesenberg, U.Falkenberg, G. Tags: micro-XRF data analysis non-negative matrix factorization NMF Ti alloys research papers Source Type: research

First experimental feasibility study of VIPIC: a custom-made detector for X-ray speckle measurements
The Vertically Integrated Photon Imaging Chip (VIPIC) was custom-designed for X-ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time- and position-stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non-zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame-oriented detectors such as charge-cou...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Rumaiz, A.K.Siddons, D.P.Deptuch, G.Maj, P.Kuczewski, A.J.Carini, G.A.Narayanan, S.Dufresne, E.M.Sandy, A.Bradford, R.Fluerasu, A.Sutton, M. Tags: VIPIC XPCS detectors research papers Source Type: research

Spontaneous emission and spectral properties of radiation by relativistic electrons in a gyro-klystron and optical-klystron undulator
In this paper spontaneous emission of radiation by relativistic electrons in a gyro-klystron is studied. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non-resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons. This leads to enhanced radiation due to klystron-type modulation as compared with a conventional gyrotron-type device driven by cyclotron maser interaction. It is shown that the klystron-modulated spectrum depends on the dispersive field strength, finit...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Prakash, B.Mishra, G.Khullar, R. Tags: undulator klystron gyrotron undulator radiation research papers Source Type: research

Calibrating the X-ray attenuation of liquid water and correcting sample movement artefacts during in operando synchrotron X-ray radiographic imaging of polymer electrolyte membrane fuel cells
Synchrotron X-ray radiography, due to its high temporal and spatial resolutions, provides a valuable means for understanding the in operando water transport behaviour in polymer electrolyte membrane fuel cells. The purpose of this study is to address the specific artefact of imaging sample movement, which poses a significant challenge to synchrotron-based imaging for fuel cell diagnostics. Specifically, the impact of the micrometer-scale movement of the sample was determined, and a correction methodology was developed. At a photon energy level of 20 keV, a maximum movement of 7.5 µm resulted in a false water thic...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Ge, N.Chevalier, S.Hinebaugh, J.Yip, R.Lee, J.Antonacci, P.Kotaka, T.Tabuchi, Y.Bazylak, A. Tags: synchrotron radiography sample movement water attenuation coefficient calibration polymer electrolyte membrane fuel cells Beer – Lambert law research papers Source Type: research

Towards hybrid pixel detectors for energy-dispersive or soft X-ray photon science
JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications at free-electron lasers and synchrotron light sources. The JUNGFRAU 0.4 prototype presented here is specifically geared towards low-noise performance and hence soft X-ray detection. The design, geometry and readout architecture of JUNGFRAU 0.4 correspond to those of other JUNGFRAU pixel detectors, which are charge-integrating detectors with 75 µm × 75 µm pixels. Main characteristics of JUNGFRAU 0.4 are its fixed gain and r.m.s. noise of as low as 27 e−...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Jungmann-Smith, J.H.Bergamaschi, A.Brückner, M.Cartier, S.Dinapoli, R.Greiffenberg, D.Huthwelker, T.Maliakal, D.Mayilyan, D.Medjoubi, K.Mezza, D.Mozzanica, A.Ramilli, M.Ruder, C.Schädler, L.Schmitt, B.Shi, X.Tinti, G. Tags: hybrid detectors soft X-rays energy-dispersive detectors instrumentation for FELs instrumentation for synchrotrons research papers Source Type: research

Optimized spatial overlap in optical pump–X-ray probe experiments with high repetition rate using laser-induced surface distortions
Ultrafast X-ray diffraction experiments require careful adjustment of the spatial overlap between the optical excitation and the X-ray probe pulse. This is especially challenging at high laser repetition rates. Sample distortions caused by the large heat load on the sample and the relatively low optical energy per pulse lead to only tiny signal changes. In consequence, this results in small footprints of the optical excitation on the sample, which turns the adjustment of the overlap difficult. Here a method for reliable overlap adjustment based on reciprocal space mapping of a laser excited thin film is presented. (Source:...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Reinhardt, M.Koc, A.Leitenberger, W.Gaal, P.Bargheer, M. Tags: ultrafast X-ray diffraction nanostructures surface deformation heat diffusion optical pump research papers Source Type: research

3D-printed photo-spectroelectrochemical devices for in situ and in operando X-ray absorption spectroscopy investigation
Three-dimensional printed multi-purpose electrochemical devices for X-ray absorption spectroscopy are presented in this paper. The aim of this work is to show how three-dimensional printing can be a strategy for the creation of electrochemical cells for in situ and in operando experiments by means of synchrotron radiation. As a case study, the description of two cells which have been employed in experiments on photoanodes for photoelectrochemical water splitting are presented. The main advantages of these electrochemical devices are associated with their compactness and with the precision of the three-dimensional printing ...
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Achilli, E.Minguzzi, A.Visibile, A.Locatelli, C.Vertova, A.Naldoni, A.Rondinini, S.Auricchio, F.Marconi, S.Fracchia, M.Ghigna, P. Tags: 3D printing in situ and in operando XAS photo-electrochemistry compact environmental cells photoanodic reactions short communications Source Type: research

The stopped-drop method: a novel setup for containment-free and time-resolved measurements
A novel setup for containment-free time-resolved experiments at a free-hanging drop is reported. Within a dead-time of 100 ms a drop of mixed reactant solutions is formed and the time evolution of a reaction can be followed from thereon by various techniques. As an example, a small-angle X-ray scattering study on the formation mechanism of EDTA-stabilized CdS both at a synchrotron and a laboratory X-ray source is presented here. While the evolution can be followed with one drop only at a synchrotron source, a stroboscopic mode with many drops is preferable for the laboratory source. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Schiener, A.Seifert, S.Magerl, A. Tags: in situ containment-free millisecond time-resolved sample environment SAXS research papers Source Type: research

Transmission X-ray scattering as a probe for complex liquid-surface structures
The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray s...
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Fukuto, M.Yang, L.Nykypanchuk, D.Kuzmenko, I. Tags: transmission X-ray scattering liquid surface scattering SAXS WAXS air/water interface research papers Source Type: research

Reference spectra of important adsorbed organic and inorganic phosphate binding forms for soil P speciation using synchrotron-based K-edge XANES spectroscopy
Direct speciation of soil phosphorus (P) by linear combination fitting (LCF) of P K-edge XANES spectra requires a standard set of spectra representing all major P species supposed to be present in the investigated soil. Here, available spectra of free- and cation-bound inositol hexakisphosphate (IHP), representing organic P, and of Fe, Al and Ca phosphate minerals are supplemented with spectra of adsorbed P binding forms. First, various soil constituents assumed to be potentially relevant for P sorption were compared with respect to their retention efficiency for orthophosphate and IHP at P levels typical for soils. Then, ...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Prietzel, J.Harrington, G.Häusler, W.Heister, K.Werner, F.Klysubun, W. Tags: LCF linear combination fitting soil phosphorus speciation spectrum deconvolution X-ray absorption near-edge spectroscopy XANES research papers Source Type: research

Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip
Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current ...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: DiLullo, A.Shirato, N.Cummings, M.Kersell, H.Chang, H.Rosenmann, D.Miller, D.Freeland, J.W.Hla, S.-W.Rose, V. Tags: synchrotron X-ray scanning tunneling microscopy smart tip XMCD chemical contrast research papers Source Type: research

Image guidance protocol for synchrotron microbeam radiation therapy
The protocol for image-guided microbeam radiotherapy (MRT) developed for the Australian Synchrotron's Imaging and Medical Beamline (IMBL) is described. The protocol has been designed for the small-animal MRT station of IMBL to enable future preclinical trials on rodents. The image guidance procedure allows for low-dose monochromatic imaging at 50 keV and subsequent semi-automated sample alignment in 3D with sub-100 µm accuracy. Following the alignment, a beamline operation mode change is performed and the relevant beamline components are automatically aligned for the treatment (pink) beam to be delivered on the s...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Pelliccia, D.Poole, C.M.Livingstone, J.Stevenson, A.W.Smyth, L.M.L.Rogers, P.A.W.Haüsermann, D.Crosbie, J.C. Tags: microbeam radiotherapy image guidance X-ray imaging X-ray tomography dosimetry research papers Source Type: research

High-speed X-ray imaging pixel array detector for synchrotron bunch isolation
A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and in...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Philipp, H.T.Tate, M.W.Purohit, P.Shanks, K.S.Weiss, J.T.Gruner, S.M. Tags: imaging detector high frame rate X-ray detector pixel array detectors time-resolved imaging area detector research papers Source Type: research

Upgrade of beamline BL08B at Taiwan Light Source from a photon-BPM to a double-grating SGM beamline
During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam-position monitor (BPM) to a testing beamline and a single-grating beamline that enables experiments to record X-ray photo-emission spectra (XPS) and X-ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X-ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano-fabrication and topological thin films are increasing. The basic spherical-grating monochromator beamline was again ...
Source: Journal of Synchrotron Radiation - August 8, 2015 Category: Physics Authors: Yuh, J.-Y.Lin, S.-W.Huang, L.-J.Fung, H.-S.Lee, L.-L.Chen, Y.-J.Cheng, C.-P.Chin, Y.-Y.Lin, H.-J. Tags: extreme ultraviolet (EUV) soft X-rays spherical-grating monochromator (SGM) beamline Taiwan Light Source photon beam-position monitor (BPM) beamlines Source Type: research

Single-crystal X-ray diffraction and resonant X-ray magnetic scattering at helium-3 temperatures in high magnetic fields at beamline P09 at PETRA III
The resonant scattering and diffraction beamline P09 at PETRA III at DESY is equipped with a 14 T vertical field split-pair magnet. A helium-3 refrigerator is available that can be fitted inside the magnet's variable-temperature insert. Here the results of a series of experiments aimed at determining the beam conditions permitting operations with the He-3 insert are presented. By measuring the tetragonal-to-orthorhombic phase transition occurring at 2.1 K in the Jahn–Teller compound TmVO4, it is found that the photon flux at P09 must be attenuated down to 1.5 × 109 photons s−1 for the sample to re...
Source: Journal of Synchrotron Radiation - August 8, 2015 Category: Physics Authors: Francoual, S.Strempfer, J.Warren, J.Liu, Y.Skaugen, A.Poli, S.Blume, J.Wolff-Fabris, F.Canfield, P.C.Lograsso, T. Tags: X-ray diffraction resonant X-ray magnetic scattering helium-3 insert cryostat sub-Kelvin temperatures X-ray beam heating single-crystal research papers Source Type: research

Optimizing X-ray mirror thermal performance using matched profile cooling
To cover a large photon energy range, the length of an X-ray mirror is often longer than the beam footprint length for much of the applicable energy range. To limit thermal deformation of such a water-cooled X-ray mirror, a technique using side cooling with a cooled length shorter than the beam footprint length is proposed. This cooling length can be optimized by using finite-element analysis. For the Kirkpatrick–Baez (KB) mirrors at LCLS-II, the thermal deformation can be reduced by a factor of up to 30, compared with full-length cooling. Furthermore, a second, alternative technique, based on a similar principle is ...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Zhang, L.Cocco, D.Kelez, N.Morton, D.S.Srinivasan, V.Stefan, P.M. Tags: KB mirror FEL beam thermal deformation variable cooling length adjustable electric heater finite-element modelling water cooling research papers Source Type: research

High-rate dead-time corrections in a general purpose digital pulse processing system
Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obta...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Abbene, L.Gerardi, G. Tags: dead-time cascade of dead-times time interval distribution digital pulse processing research papers Source Type: research

A new method for studying sub-pulse dynamics at synchrotron sources
The possibility of studying dynamics at time scales on the order of the pulse duration at synchrotron X-ray sources with present avalanche photodiode point detection technology is investigated, without adopting pump–probe techniques. It is found that sample dynamics can be characterized by counting single and double photon events and an analytical approach is developed to estimate the time required for a statistically significant measurement to be made. The amount of scattering required to make such a measurement possible presently within a few days is indicated and it is shown that at next-generation synchrotron sou...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Wingert, J.Singer, A.Shpyrko, O.G. Tags: coherent X-ray scattering speckle statistics ultrafast dynamics XPCS research papers Source Type: research

Time delay measurement in the frequency domain
Pump–probe studies at synchrotrons using X-ray and laser pulses require accurate determination of the time delay between pulses. This becomes especially important when observing ultrafast responses with lifetimes approaching or even less than the X-ray pulse duration (∼100 ps). The standard approach of inspecting the time response of a detector sensitive to both types of pulses can have limitations due to dissimilar pulse profiles and other experimental factors. Here, a simple alternative is presented, where the frequency response of the detector is monitored versus time delay. Measurements readily demonstrate ...
Source: Journal of Synchrotron Radiation - August 6, 2015 Category: Physics Authors: Durbin, S.M.Liu, S.-C.Dufresne, E.M.Li, Y.Wen, H. Tags: pump – probe X-ray synchrotron ultrafast time resolution RF frequency analysis short communications Source Type: research

Py4Syn: Python for synchrotrons
In this report, Py4Syn, an open-source Python-based library for data acquisition, device manipulation, scan routines and other helper functions, is presented. Driven by easy-to-use and scalability ideals, Py4Syn offers control system agnostic solution and high customization level for scans and data output, covering distinct techniques and facilities. Here, most of the library functionalities are described, examples of use are shown and ideas for future implementations are presented. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 6, 2015 Category: Physics Authors: Slepicka, H.H.Canova, H.F.Beniz, D.B.Piton, J.R. Tags: Python Py4Syn data acquisition devices research papers Source Type: research

SIMPLEX: simulator and postprocessor for free-electron laser experiments
SIMPLEX is a computer program developed for simulating the amplification process of free-electron lasers (FELs). It numerically solves the so-called FEL equations describing the evolution of the radiation field and growth of microbunching while the electron beam travels along the undulator. In order to reduce the numerical cost, the FEL equations have been reduced to more convenient forms for numerical implementation by applying reasonable approximations. SIMPLEX is equipped with a postprocessor to facilitate the retrieval of desired information from the simulation results, which is crucial for practical applications such ...
Source: Journal of Synchrotron Radiation - August 5, 2015 Category: Physics Authors: Tanaka, T. Tags: free-electron laser simulation computer programs Source Type: research

On the ANKA decision: a response to Braun's Just for us?
KIT's Executive Board has decided to discontinue the operation of the synchrotron radiation facility ANKA within category LK-II (user facility) of the Helmholtz Association and continue operation in LK-I (research). The KIT Senate confirmed this decision. Some aspects of the background and the rationale leading to this change are explained. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Saile, V. Tags: ANKA KIT user facility letters to the editor Source Type: research

Just for us?
It is a regrettable decision by Karlsruhe Institute of Technology that ANKA, the Angströmquelle Karlsruhe, is terminating its external synchrotron user support program. ANKA has an excellent performance review grading sheet and has been a valuable source and resource to international users for over a decade. There is concern among users that ANKA's decision could become an example for other synchrotrons as well. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Braun, A. Tags: Angstr ö mquelle Karlsruhe ANKA technology-based research synchrotron facility user program letters to the editor Source Type: research

A sub-micrometer resolution hard X-ray microprobe system of BL8C at Pohang Light Source
A microprobe system has been installed on the nanoprobe/XAFS beamline (BL8C) at PLS-II, South Korea. Owing to the reproducible switch of the gap of the in-vacuum undulator (IVU), the intense and brilliant hard X-ray beam of an IVU can be used in X-ray fluorescence (XRF) and X-ray absorption fine-structure (XAFS) experiments. For high-spatial-resolution microprobe experiments a Kirkpatrick–Baez mirror system has been used to focus the millimeter-sized X-ray beam to a micrometer-sized beam. The performance of this system was examined by a combination of micro-XRF imaging and micro-XAFS of a beetle wing. These results i...
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Sung, N.-E.Lee, I.-J.Lee, K.-S.Jeong, S.-H.Kang, S.-W.Shin, Y.-B. Tags: X-ray instrumentation microprobe XAFS micro-XRF micro-XANES beamlines Source Type: research

Muffin-tin potentials in EXAFS analysis
Muffin-tin potentials are the standard tool for calculating the potential surface of a cluster of atoms for use in the analysis of extended X-ray absorption fine-structure (EXAFS) data. The set of Cartesian coordinates used to define the positions of atoms in the cluster and to calculate the muffin-tin potentials is commonly also used to enumerate the scattering paths used in the EXAFS data analysis. In this paper, it is shown that these muffin-tin potentials are sufficiently robust to be used to examine quantitatively contributions to the EXAFS data from scattering geometries not represented in the original cluster. (Sour...
Source: Journal of Synchrotron Radiation - July 25, 2015 Category: Physics Authors: Ravel, B. Tags: EXAFS real-space multiple scattering data analysis muffin-tin potential research papers Source Type: research

On EXAFS Debye-Waller factor and recent advances
The effects of structural and vibrational disorder on the EXAFS signals are parameterized in terms of the Debye Waller (DW) factor. Here the vibrational contribution is addressed, which for most systems can be singled out by studying the temperature dependence of the EXAFS DW factor, which corresponds to a good accuracy to the parallel mean square relative displacement (MSRD) around the inter-atomic equilibrium distance. By comparing the first-shell EXAFS thermal expansion with the crystallographic thermal expansion one can evaluate the perpendicular MSRD. The results of recent measurements on copper and on several tetrahe...
Source: Journal of Synchrotron Radiation - July 22, 2015 Category: Physics Authors: Fornasini, P.Grisenti, R. Tags: EXAFS thermal disorder Debye-Waller factor Einstein model Debye model research papers Source Type: research

Optimized IR synchrotron beamline design
Synchrotron infrared beamlines are powerful tools on which to perform spectroscopy on microscopic length scales but require working with large bending-magnet source apertures in order to provide intense photon beams to the experiments. Many infrared beamlines use a single toroidal-shaped mirror to focus the source emission which generates, for large apertures, beams with significant geometrical aberrations resulting from the shape of the source and the beamline optics. In this paper, an optical layout optimized for synchrotron infrared beamlines, that removes almost totally the geometrical aberrations of the source, is pre...
Source: Journal of Synchrotron Radiation - July 22, 2015 Category: Physics Authors: Moreno, T. Tags: infrared synchrotron beamline bending magnet optical aberrations optical path research papers Source Type: research

A plug-and-measure diagnostic tool for flux, resolution and beam size of a soft X-ray beamline
A compact multi-functional diagnostic tool has been installed for commissioning beamlines at the Taiwan Light Source. For a photon beam, the instrument can measure the photon flux, energy resolution and beam size, consecutively with a photodiode or gold mesh, a windowless gas cell and a movable fluorescence screen viewport. Two gratings with ruling densities of 350 and 1000 lines mm−1 and dispersing photons of energies from 80 to 1200 eV were calibrated with a photon flux of 1011 photon s−1 at slit openings of 50 µm × 50 µm; a maximum resolving power of greater than 10000 was certi...
Source: Journal of Synchrotron Radiation - July 21, 2015 Category: Physics Authors: Wei, C.-H.Lin, H.-C.Lin, S.-W.Yuh, J.-Y. Tags: windowless ion chamber soft X-ray beamline gas phase absorption dynamic beam size monitor short communications Source Type: research

Investigating structural aspects to understand the putative/claimed non-toxicity of the Hg-based Ayurvedic drug Rasasindura using XAFS
XANES- and EXAFS-based analysis of the Ayurvedic Hg-based nano-drug Rasasindura has been performed to seek evidence of its non-toxicity. Rasasindura is determined to be composed of single-phase α-HgS nanoparticles (size ∼24 nm), free of Hg0 or organic molecules; its structure is determined to be robust ( (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - July 21, 2015 Category: Physics Authors: Ramanan, N.Lahiri, D.Rajput, P.Varma, R.C.Arun, A.Muraleedharan, T.S.Pandey, K.K.Maiti, N.Jha, S.N.Sharma, S.M. Tags: Ayurvedic drug XAFS Hg toxicity research papers Source Type: research

Exploring experimental parameter choice for rapid speckle-tracking phase-contrast X-ray imaging with a paper analyzer
Phase-contrast X-ray imaging using a paper analyzer enables the visualization of X-ray transparent biological structures using the refractive properties of the sample. The technique measures the sample-induced distortions of a spatially random reference pattern to retrieve quantitative sample information. This phase-contrast method is promising for biomedical application due to both a simple experimental set-up and a capability for real-time imaging. The authors explore the experimental configuration required to achieve robustness and accuracy in terms of (i) the paper analyzer feature size, (ii) the sample-to-detector dis...
Source: Journal of Synchrotron Radiation - July 21, 2015 Category: Physics Authors: Aloisio, I.A.Paganin, D.M.Wright, C.A.Morgan, K.S. Tags: X-ray imaging phase contrast phase retrieval speckle imaging research papers Source Type: research

Development of dispersive XAFS system for analysis of time-resolved spatial distribution of electrode reaction
Apparatus for a technique based on the dispersive optics of X-ray absorption fine structure (XAFS) has been developed at beamline BL-5 of the Synchrotron Radiation Center of Ritsumeikan University. The vertical axis of the cross section of the synchrotron light is used to disperse the X-ray energy using a cylindrical polychromator and the horizontal axis is used for the spatially resolved analysis with a pixel array detector. The vertically dispersive XAFS (VDXAFS) instrument was designed to analyze the dynamic changeover of the inhomogeneous electrode reaction of secondary batteries. The line-shaped X-ray beam is transmit...
Source: Journal of Synchrotron Radiation - July 17, 2015 Category: Physics Authors: Katayama, M.Miyahara, R.Watanabe, T.Yamagishi, H.Yamashita, S.Kizaki, T.Sugawara, Y.Inada, Y. Tags: DXAFS imaging polychromator Li ion secondary battery reaction distribution research papers Source Type: research

Ultra-stable sub-meV monochromator for hard X-rays
A high-resolution silicon monochromator suitable for 21.541 keV synchrotron radiation is presented that produces a bandwidth of 0.27 meV. The operating energy corresponds to a nuclear transition in 151Eu. The first-of-its-kind, fully cryogenic design achieves an energy-alignment stability of 0.017 meV r.m.s. per day, or a 100-fold improvement over other meV-monochromators, and can tolerate higher X-ray power loads than room-temperature designs of comparable resolution. This offers the potential for significantly more accurate measurements of lattice excitation energies using nuclear resonant vibrational spectroscopy ...
Source: Journal of Synchrotron Radiation - July 17, 2015 Category: Physics Authors: Toellner, T.S.Collins, J.Goetze, K.Hu, M.Y.Preissner, C.Trakhtenberg, E.Yan, L. Tags: high energy-resolution monochromator europium nuclear resonance cryostat research papers Source Type: research

XAS analysis of iron and palladium bonded to a polysaccharide produced anaerobically by a strain of Klebsiella oxytoca
Klebsiella oxytoca BAS-10 ferments citrate to acetic acid and CO2, and secretes a specific exopolysaccharide (EPS), which is able to bind different metallic species. These biomaterials may be used for different biotechnological purposes, including applications as innovative green biogenerated catalysts. In production of biogenerated Pd species, the Fe(III) as ferric citrate is added to anaerobic culture of K. oxytoca BAS-10, in the presence of palladium species, to increase the EPS secretion and improve Pd-EPS yield. In this process, bi-metallic (FePd-EPS) biomaterials were produced for the first time. The morphology of ...
Source: Journal of Synchrotron Radiation - July 16, 2015 Category: Physics Authors: Arčon, I.Paganelli, S.Piccolo, O.Gallo, M.Vogel-Mikuš, K.Baldi, F. Tags: citrate fermentation bi-metallic exopolysaccharide Fe K-edge Pd K-edge XANES EXAFS µ -XRF research papers Source Type: research

Design of a mouse restraint for synchrotron-based computed tomography imaging
High-resolution computed tomography (CT) imaging of a live animal within a lead-lined synchrotron light hutch presents several unique challenges. In order to confirm that the animal is under a stable plane of anaesthesia, several physiological parameters (e.g. heart rate, arterial oxygen saturation, core body temperature and respiratory rate) must be remotely monitored from outside the imaging hutch. In addition, to properly scan the thoracic region using CT, the animal needs to be held in a vertical position perpendicular to the fixed angle of the X-ray beam and free to rotate 180°–360°. A new X-ray transpar...
Source: Journal of Synchrotron Radiation - July 15, 2015 Category: Physics Authors: Gagnon, K.B.Caine, S.Samadi, N.Martinson, M.van der Loop, M.Alcorn, J.Chapman, L.D.Belev, G.Nichol, H. Tags: three-dimensional printing computer-aided design remote physiological monitoring anaesthesia X-ray imaging short communications Source Type: research

Influence of higher harmonics of the undulator in X-ray polarimetry and crystal monochromator design
The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - July 15, 2015 Category: Physics Authors: Marx-Glowna, B.Schulze, K.S.Uschmann, I.Kämpfer, T.Weber, G.Hahn, C.Wille, H.-C.Schlage, K.Röhlsberger, R.Förster, E.Stöhlker, T.Paulus, G.G. Tags: polarimetry monochromator Compton scattering X-ray diffraction undulator high harmonics research papers Source Type: research

Optimal azimuthal orientation for Si(111) double-crystal monochromators to achieve the least amount of glitches in the hard X-ray region
Simulations of the periods, split regularities and mirror symmetries of the glitch pattern of a Si(111) crystal along with the azimuthal angles are presented. The glitch patterns of Si(111) double-crystal monochromators (DCMs) are found to be the superposition of the two sets of glitch patterns from the two crystals. The optimal azimuthal orientation ϕ1,2 = [(2n+1)π]/6 (n = 0, ±1, ±2…) for Si(111) DCMs to achieve the least amount of glitches in the hard X-ray region has been suggested. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - July 15, 2015 Category: Physics Authors: Tang, Z.Zheng, L.Chu, S.Wu, M.An, P.Zhang, L.Hu, T. Tags: double-crystal monochromator multiple-beam diffraction glitches optimal azimuthal orientation XAFS research papers Source Type: research

Towards a microchannel-based X-ray detector with two-dimensional spatial and time resolution and high dynamic range
X-ray detectors that combine two-dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time-gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter-scale spatial resolution and better than 100 ps time resolution. The technology ...
Source: Journal of Synchrotron Radiation - July 15, 2015 Category: Physics Authors: Adams, B.W.Mane, A.U.Elam, J.W.Obaid, R.Wetstein, M.Chollet, M. Tags: high dynamic range microchannel-based X-ray detector research papers Source Type: research

A soft X-ray plane-grating monochromator optimized for elliptical dipole radiation from modern sources
A new but yet well proven way of making elliptically polarized dipole radiation from the BESSY II storage ring applicable to the SX700-type collimated plane-grating monochromator PM3 is described. It is shown that due to the limited vertical acceptance of the grating a simple use of vertical apertures is not possible in this case. Rather, deflecting the beam upwards or downwards by rotating the vertically collimating toroidal mirror M1 around the light axis leads to excellent performance. The resulting detuning of the photon energy can be taken into account by a readjustment of the monochromator internal plane mirror M2....
Source: Journal of Synchrotron Radiation - July 14, 2015 Category: Physics Authors: Kachel, T.Eggenstein, F.Follath, R. Tags: soft X-rays plane-grating monochromator PGM elliptical polarization dipole radiation beamlines Source Type: research

Ring artifacts correction in compressed sensing tomographic reconstruction
Ring artifacts are a very common problem in tomographic reconstruction, and numerous methods exist to either pre-process the sinogram or correct the reconstructed slice. A novel approach to perform the correction as part of the reconstruction process is presented. It is shown that for iterative techniques, which amount to optimizing an objective function, the ring artifacts correction can be easily integrated in the formalism, enabling simultaneous slice reconstruction and ring artifacts correction. This method is tested and compared with mainstream correction techniques for both simulated and experimental data. Results sh...
Source: Journal of Synchrotron Radiation - July 14, 2015 Category: Physics Authors: Paleo, P.Mirone, A. Tags: tomography artifacts compressed sensing research papers Source Type: research

A novel imaging tool for hepatic portal system using phase contrast technique with hydrogen peroxide-generated O2 gas
The objective of this study was to investigate the potential of hydrogen peroxide-generated oxygen gas-based phase contrast imaging (PCI) for visualizing mouse hepatic portal veins. The O2 gas was made from the reaction between H2O2 and catalase. The gas production was imaged by PCI in real time. The H2O2 was injected into the enteric cavity of the lower sigmoid colon to produce O2 in the submucosal venous plexus. The generated O2 gas could be finally drained into hepatic portal veins. Absorption contrast imaging (ACI) and PCI of O2-filled portal veins were performed and compared. PCI offers high resolution and real-time v...
Source: Journal of Synchrotron Radiation - July 13, 2015 Category: Physics Authors: Tang, R.Yan, F.Chai, W.-M.Huang, W.Fu, Y.Yang, G.-Y.Chen, K.-M. Tags: X-ray phase contrast imaging O2 gas hepatic portal vein hydrogen peroxide research papers Source Type: research

Current events
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - June 30, 2015 Category: Physics Authors: , Tags: current events Source Type: research

Optical design and multi-length-scale scanning spectro-microscopy possibilities at the Nanoscopium beamline of Synchrotron Soleil
The Nanoscopium 155 m-long beamline of Synchrotron Soleil is dedicated to scanning hard X-ray nanoprobe techniques. Nanoscopium aims to reach ≤100 nm resolution in the 5–20 keV energy range for routine user experiments. The beamline design tackles the tight stability requirements of such a scanning nanoprobe by creating an overfilled secondary source, implementing all horizontally reflecting main beamline optics, applying high mechanical stability equipment and constructing a dedicated high-stability building envelope. Multi-technique scanning imaging and tomography including X-ray fluorescence spectrometry ...
Source: Journal of Synchrotron Radiation - June 27, 2015 Category: Physics Authors: Somogyi, A.Medjoubi, K.Baranton, G.Le Roux, V.Ribbens, M.Polack, F.Philippot, P.Samama, J.-P. Tags: scanning hard X-ray nanoprobe hierarchical length-scale imaging multimodal techniques spectro-microscopy morphology beamlines Source Type: research

Real-space multiple-scattering Hubbard model calculations for d- and f-state materials
Calculations are presented of the electronic structure and X-ray spectra of materials with correlated d- and f-electron states based on the Hubbard model, a real-space multiple-scattering formalism and a rotationally invariant local density approximation. Values of the Hubbard parameter are calculated ab initio using the constrained random-phase approximation. The combination of the real-space Green's function with Hubbard model corrections provides an efficient approach to describe localized correlated electron states in these systems, and their effect on core-level X-ray spectra. Results are presented for the projec...
Source: Journal of Synchrotron Radiation - June 27, 2015 Category: Physics Authors: Vorwerk, C.Jorissen, K.Rehr, J.Ahmed, T. Tags: X-ray absorption spectroscopy multiple scattering XANES Hubbard model research papers Source Type: research

HERMES: a soft X-ray beamline dedicated to X-ray microscopy
The HERMES beamline (High Efficiency and Resolution beamline dedicated to X-ray Microscopy and Electron Spectroscopy), built at Synchrotron SOLEIL (Saint-Auban, France), is dedicated to soft X-ray microscopy. The beamline combines two complementary microscopy methods: XPEEM (X-ray Photo Emitted Electron Microscopy) and STXM (Scanning Transmission X-ray Microscopy) with an aim to reach spatial resolution below 20 nm and to fully exploit the local spectroscopic capabilities of the two microscopes. The availability of the two methods within the same beamline enables the users to select the appropriate approach to study thei...
Source: Journal of Synchrotron Radiation - June 27, 2015 Category: Physics Authors: Belkhou, R.Stanescu, S.Swaraj, S.Besson, A.Ledoux, M.Hajlaoui, M.Dalle, D. Tags: photoemission microscopy XPEEM STXM X-ray microscopy synchrotron beamline beamline design monochromator soft X-ray optics research papers Source Type: research

Resonant inelastic X-ray scattering spectrometer with 25 meV resolution at the Cu K-edge
An unparalleled resolution is reported with an inelastic X-ray scattering instrument at the Cu K-edge. Based on a segmented concave analyzer, featuring single-crystal quartz (SiO2) pixels, the spectrometer delivers a resolution near 25 meV (FWHM) at 8981 eV. Besides the quartz analyzer, the performance of the spectrometer relies on a four-bounce Si(553) high-resolution monochromator and focusing Kirkpatrick–Baez optics. The measured resolution agrees with the ray-tracing simulation of an ideal spectrometer. The performance of the spectrometer is demonstrated by reproducing the phonon dispersion curve of a berylli...
Source: Journal of Synchrotron Radiation - June 27, 2015 Category: Physics Authors: Ketenoglu, D.Harder, M.Klementiev, K.Upton, M.Taherkhani, M.Spiwek, M.Dill, F.-U.Wille, H.-C.Yavaş, H. Tags: resonant inelastic X-ray scattering (RIXS) high energy-resolution diced crystal analyzers quartz research papers Source Type: research