Investigation of nanoparticulate silicon as printed layers using scanning electron microscopy, transmission electron microscopy, X-ray absorption spectroscopy and X-ray photoelectron spectroscopy
The presence of native oxide on the surface of silicon nanoparticles is known to inhibit charge transport on the surfaces. Scanning electron microscopy (SEM) studies reveal that the particles in the printed silicon network have a wide range of sizes and shapes. High-resolution transmission electron microscopy reveals that the particle surfaces have mainly the (111)- and (100)-oriented planes which stabilizes against further oxidation of the particles. X-ray absorption spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) measurements at the O 1s-edge have been utilized to study the oxidation and local atomic stru...
Source: Journal of Synchrotron Radiation - August 21, 2017 Category: Physics Authors: Unuigbe, D.M. Harting, M. Jonah, E.O. Britton, D.T. Nordlund, D. Tags: native oxide charge transport sub-oxide states XANES XPS SEM network structures printed layers research papers Source Type: research

Local structure around In atoms in coherently grown m-plane InGaN film
The local structure around In atoms in an m-plane In0.06Ga0.94N film coherently grown on a freestanding m-plane GaN substrate was investigated by polarization-dependent X-ray absorption fine-structure. A step-by-step fitting procedure was proposed for the m-plane wurtzite structure. The interatomic distance for the first nearest neighbour In — N atomic pairs was almost isotropic. For the second nearest In — Ga pairs, the interatomic distances along the m- and a-axes were longer and shorter, respectively, than that in strain-free virtual crystals as expected for the m-plane compressive strain. In contrast, the I...
Source: Journal of Synchrotron Radiation - August 21, 2017 Category: Physics Authors: Miyanaga, T. Azuhata, T. Nitta, K. Chichibu, S.F. Tags: m-plane InGaN XAFS local structure step-by-step fitting procedure research papers Source Type: research

Mutual optical intensity propagation through non-ideal mirrors
The mutual optical intensity (MOI) model is extended to include the propagation of partially coherent radiation through non-ideal mirrors. The propagation of the MOI from the incident to the exit plane of the mirror is realised by local ray tracing. The effects of figure errors can be expressed as phase shifts obtained by either the phase projection approach or the direct path length method. Using the MOI model, the effects of figure errors are studied for diffraction-limited cases using elliptical cylinder mirrors. Figure errors with low spatial frequencies can vary the intensity distribution, redistribute the local coher...
Source: Journal of Synchrotron Radiation - August 18, 2017 Category: Physics Authors: Meng, X. Shi, X. Wang, Y. Reininger, R. Assoufid, L. Tai, R. Tags: partially coherent radiation mutual optical intensity non-ideal mirrors beamline design mirror figure errors research papers Source Type: research

Characterization of enamel caries lesions in rat molars using synchrotron X-ray microtomography
Dental caries is a ubiquitous infectious disease with a nearly 100% lifetime prevalence. Rodent caries models are widely used to investigate the etiology, progression and potential prevention or treatment of the disease. To explore the suitability of these models for deeper investigations of intact surface zones during enamel caries, the structures of early-stage carious lesions in rats were characterized and compared with previous reports on white spot enamel lesions in humans. Synchrotron X-ray microcomputed tomography non-destructively mapped demineralization in carious rat molar specimens across a range of caries sever...
Source: Journal of Synchrotron Radiation - August 18, 2017 Category: Physics Authors: Free, R.D. DeRocher, K. Stock, S.R. Keane, D. Scott-Anne, K. Bowen, W.H. Joester, D. Tags: X-ray microtomography white spot enamel lesions surface zones caries research papers Source Type: research

Non-uniform nanosecond gate-delay of hybrid pixel   detectors
A simple experiment to characterize the gating properties of X-ray area detectors using pulsed X-ray sources is presented. For a number of time-resolved experiments the gating uniformity of area detectors is important. Relative gating delays between individual modules and readout chips of PILATUS2   series area X-ray detectors have been observed. For three modules of a PILATUS   300K-W unit the maximum gating offset between the modules is found to be as large as 30   ns. On average, the first photosensor module is found to be triggered 15   ns and 30   ns later than the second and the third modules, respective...
Source: Journal of Synchrotron Radiation - August 17, 2017 Category: Physics Authors: Shayduk, R. Pennicard, D. Krausert, K. Gaal, P. Volkov, S. Vonk, V. Hejral, U. Jankowski, M. Reinhardt, M. Leitenberger, W. Stierle, A. Tags: pump – probe X-ray diffraction hybrid pixel X-ray detector triggering timing jitter short communications Source Type: research

In operando quantitation of Li concentration for a commercial Li-ion rechargeable battery using high-energy X-ray Compton scattering
In this study, S-parameter analysis has been applied to a commercial coin cell Li-ion rechargeable battery and the variation of the S-parameters during the charge/discharge cycle at the positive and negative electrodes has been obtained. By using calibration curves for Li composition in the electrodes, the change in Li composition of the positive and negative electrodes has been determined using the S-parameters simultaneously. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 17, 2017 Category: Physics Authors: Suzuki, K. Suzuki, A. Ishikawa, T. Itou, M. Yamashige, H. Orikasa, Y. Uchimoto, Y. Sakurai, Y. Sakurai, H. Tags: Li-ion battery in operando measurement quantitation Compton profile research papers Source Type: research

Estimating the absolute flux distribution for a synchrotron X-ray beam using ionization-chamber measurements with various filters
It is shown that an extensive set of accurate ionization-chamber measurements with a primary polychromatic synchrotron X-ray beam transmitted through various filter combinations/thicknesses can be used to quite effectively estimate the absolute flux distribution. The basic technique is simple but the `inversion' of the raw data to extract the flux distribution is a fundamentally ill-posed problem. It is demonstrated, using data collected at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron, that the absolute flux can be quickly and reliably estimated if a suitable choice of filters is made. Results are ...
Source: Journal of Synchrotron Radiation - August 11, 2017 Category: Physics Authors: Stevenson, A.W. Di Lillo, F. Tags: ionization chambers filters X-ray beam quality harmonic contamination research papers Source Type: research

Confocal depth-resolved fluorescence micro-X-ray absorption spectroscopy for the study of cultural heritage materials: a new mobile endstation at the Beijing Synchrotron Radiation Facility
A confocal fluorescence endstation for depth-resolved micro-X-ray absorption spectroscopy is described. A polycapillary half-lens defines the incident beam path and a second polycapillary half-lens at 90 ° defines the probe sample volume. An automatic alignment program based on an evolutionary algorithm is employed to make the alignment procedure efficient. This depth-resolved system was examined on a general X-ray absorption spectroscopy (XAS) beamline at the Beijing Synchrotron Radiation Facility. Sacrificial red glaze (AD   1368 – 1644) china was studied to show the capability of the instrument. As a mobile ...
Source: Journal of Synchrotron Radiation - August 10, 2017 Category: Physics Authors: Chen, G. Chu, S. Sun, T. Sun, X. Zheng, L. An, P. Zhu, J. Wu, S. Du, Y. Zhang, J. Tags: confocal XAS mobile endstation sacrificial red glaze depth-dependent valence distribution research papers Source Type: research

Characterization of individual stacking faults in a   wurtzite GaAs nanowire by nanobeam X-ray diffraction
Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [000\bar{1}] direction in the vicinity of the wurtzite 00\bar{1}\bar{5} Bragg peak. T...
Source: Journal of Synchrotron Radiation - August 9, 2017 Category: Physics Authors: Davtyan, A. Lehmann, S. Kriegner, D. Zamani, R.R. Dick, K.A. Bahrami, D. Al-Hassan, A. Leake, S.J. Pietsch, U. Hol ý , V. Tags: stacking faults Patterson function nanowire coherent nanobeam X-ray diffraction research papers Source Type: research

The EIGER detector for low-energy electron microscopy and photoemission electron microscopy
EIGER is a single-photon-counting hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland. It is designed for applications at synchrotron light sources with photon energies above 5   keV. Features of EIGER include a small pixel size (75   µ m × 75   µ m), a high frame rate (up to 23   kHz), a small dead-time between frames (down to 3   µ s) and a dynamic range up to 32-bit. In this article, the use of EIGER as a detector for electrons in low-energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) is reported. It is demonstrated that, with only a mi...
Source: Journal of Synchrotron Radiation - August 9, 2017 Category: Physics Authors: Tinti, G. Marchetto, H. Vaz, C.A.F. Kleibert, A. Andr ä , M. Barten, R. Bergamaschi, A. Br ü ckner, M. Cartier, S. Dinapoli, R. Franz, T. Fr ö jdh, E. Greiffenberg, D. Lopez-Cuenca, C. Mezza, D. Mozzanica, A. Nolting, F. Ramilli, M. Redford, S. Ruat, M Tags: single-photon counters hybrid pixel detectors instrumentation for synchrotron radiation accelerators X-ray detectors PEEM LEEM research papers Source Type: research

Strategies for high-throughput focused-beam ptychography
X-ray ptychography is being utilized for a wide range of imaging experiments with a resolution beyond the limit of the X-ray optics used. Introducing a parameter for the ptychographic resolution gain Gp (the ratio of the beam size over the achieved pixel size in the reconstructed image), strategies for data sampling and for increasing imaging throughput when the specimen is at the focus of an X-ray beam are considered. The tradeoffs between large and small illumination spots are examined. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 8, 2017 Category: Physics Authors: Jacobsen, C. Deng, J. Nashed, Y. Tags: ptychography ptychographic resolution gain high throughput short communications Source Type: research

Observation of an optical vortex beam from a helical undulator in the XUV region
The observation of an optical vortex beam at 60   nm wavelength, produced as the second-harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation. (Source: Jour...
Source: Journal of Synchrotron Radiation - August 8, 2017 Category: Physics Authors: Kaneyasu, T. Hikosaka, Y. Fujimoto, M. Iwayama, H. Hosaka, M. Shigemasa, E. Katoh, M. Tags: XUV vortex helical undulator radiation interference research papers Source Type: research

Micro-beam Laue alignment of multi-reflection Bragg coherent diffraction imaging measurements
Multi-reflection Bragg coherent diffraction imaging has the potential to allow three-dimensional (3D) resolved measurements of the full lattice strain tensor in specific micro-crystals. Until now such measurements were hampered by the need for laborious, time-intensive alignment procedures. Here a different approach is demonstrated, using micro-beam Laue X-ray diffraction to first determine the lattice orientation of the micro-crystal. This information is then used to rapidly align coherent diffraction measurements of three or more reflections from the crystal. Based on these, 3D strain and stress fields in the crystal are...
Source: Journal of Synchrotron Radiation - August 8, 2017 Category: Physics Authors: Hofmann, F. Phillips, N.W. Harder, R.J. Liu, W. Clark, J.N. Robinson, I.K. Abbey, B. Tags: Bragg coherent diffraction imaging micro-beam Laue diffraction ion implantation strain tensor measurement research papers Source Type: research

Flyscan opportunities in medicine: the case of quantum rattle based on gold quantum dots
This study presents a complete set of data acquired after injection of gold-cluster-enriched mesoporous silica nanospheres, used as potential theranostic vectors, into rats. While classical X-ray fluorescence investigations (using step-by-step acquisitions) are based on a limited number of samples (approximately one per day at the DiffAbs beamline), the Flyscan mode has enabled gathering information on the interaction of nanometer-scale vectors in different organs such as liver, spleen and kidney at the micrometer scale, for five rats, in only a single five-day synchrotron shift. Moreover, numerous X-ray absorption near-ed...
Source: Journal of Synchrotron Radiation - August 7, 2017 Category: Physics Authors: Esteve, E. Reguer, S. Boissiere, C. Chaneac, C. Lugo, G. Jouanneau, C. Mocuta, C. Thiaudiere, D. Leclercq, N. Leyh, B. Greisch, J.-F. Berthault, J. Daudon, M. Ronco, P. Bazin, D. Tags: Flyscan method theranostic vectors gold-cluster-enriched mesoporous silica nanospheres X-ray fluorescence XANES research papers Source Type: research

Electron-bunch lengthening on higher-harmonic oscillations in storage-ring free-electron lasers
The influence of higher-harmonic free-electron laser (FEL) oscillations on an electron beam have been studied by measuring its bunch length at the NIJI-IV storage ring. The bunch length and the lifetime of the electron beam were measured, and were observed to have become longer owing to harmonic lasing, which is in accord with the increase of the FEL gain. It was demonstrated that the saturated FEL power could be described by the theory of bunch heating, even for the harmonic lasing. Cavity-length detuning curves were measured for the harmonic lasing, and it was found that the width of the detuning curve was proportional t...
Source: Journal of Synchrotron Radiation - August 7, 2017 Category: Physics Authors: Sei, N. Ogawa, H. Okuda, S. Tags: free-electron laser higher-harmonic oscillation bunch length detuning curve research papers Source Type: research

Analysis of the microvascular morphology and hemodynamics of breast cancer in mice using SPring-8 synchrotron radiation microangiography
In this study, mice bearing the human breast cancer cell lines MDAMB231 and NOTCH4 overexpression in MDAMB231 (MDAMB231NOTCH4+) and normal mice were assessed using SR microangiography. NOTCH is transmembrane protein that has crucial roles for vasculogenesis, angiogenesis and tumorigenesis, and NOTCH4 is considered to be a cause of high-flow arteriovenous shunting. A subgroup of mice received intravenous eribulin treatment, which is known to improve intratumor core circulation (MDAMB231_eribulin). Microvessel branches from approximately 200   µ m to less than 20   µ m in diameter were observed within the sam...
Source: Journal of Synchrotron Radiation - August 2, 2017 Category: Physics Authors: Torii, M. Fukui, T. Inoue, M. Kanao, S. Umetani, K. Shirai, M. Inagaki, T. Tsuchimochi, H. Pearson, J.T. Toi, M. Tags: tumor microvessels hemodynamics quantitative analysis SR microangiography research papers Source Type: research

Simulated sample heating from a nanofocused X-ray beam
Recent developments in synchrotron brilliance and X-ray optics are pushing the flux density in nanofocusing experiments to unprecedented levels, which increases the risk of different types of radiation damage. The effect of X-ray induced sample heating has been investigated using time-resolved and steady-state three-dimensional finite-element modelling of representative nanostructures. Simulations of a semiconductor nanowire indicate that the heat generated by X-ray absorption is efficiently transported within the nanowire, and that the temperature becomes homogeneous after about 5   ns. The most important channel for he...
Source: Journal of Synchrotron Radiation - August 2, 2017 Category: Physics Authors: Wallander, H. Wallentin, J. Tags: heating radiation damage simulation nanostructures research papers Source Type: research

A protocol for searching the most probable phase-retrieved maps in coherent X-ray diffraction imaging by exploiting the relationship between convergence of the retrieved phase and success of calculation
Coherent X-ray diffraction imaging (CXDI) is a technique for visualizing the structures of non-crystalline particles with size in the submicrometer to micrometer range in material sciences and biology. In the structural analysis of CXDI, the electron density map of a specimen particle projected along the direction of the incident X-rays can be reconstructed only from the diffraction pattern by using phase-retrieval (PR) algorithms. However, in practice, the reconstruction, relying entirely on the computational procedure, sometimes fails because diffraction patterns miss the data in small-angle regions owing to the beam sto...
Source: Journal of Synchrotron Radiation - August 1, 2017 Category: Physics Authors: Sekiguchi, Y. Hashimoto, S. Kobayashi, A. Oroguchi, T. Nakasako, M. Tags: coherent X-ray diffraction imaging X-ray free-electron laser structure analysis of   non-crystalline particles phase retrieval calculation research papers Source Type: research

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring
The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedan...
Source: Journal of Synchrotron Radiation - August 1, 2017 Category: Physics Authors: Tanabe, T. Bassan, H. Broadbent, A. Cappadoro, P. Escallier, J. Harder, D. Hetzel, C. Hidas, D. Kitegi, C. Kosciuk, B. Musardo, M. Kirkland, J. Tags: insertion devices synchrotron light source in-vacuum undulator (IVU) storage ring research papers Source Type: research

WIFIP: a web-based user interface for automated synchrotron beamlines
The beamline control software, through the associated graphical user interface (GUI), is the user access point to the experiment, interacting with synchrotron beamline components and providing automated routines. FIP, the French beamline for the Investigation of Proteins, is a highly automatized macromolecular crystallography (MX) beamline at the European Synchrotron Radiation Facility. On such a beamline, a significant number of users choose to control their experiment remotely. This is often performed with a limited bandwidth and from a large choice of computers and operating systems. Furthermore, this has to be possible...
Source: Journal of Synchrotron Radiation - July 28, 2017 Category: Physics Authors: Sallaz-Damaz, Y. Ferrer, J.-L. Tags: graphical user interface web-based macromolecular crystallography automated beamline computer programs Source Type: research

Atomic pair distribution function at the Brazilian Synchrotron Light Laboratory: application to the Pb1 – xLaxZr0.40Ti0.60O3 ferroelectric system
This work reports the setting up of the X-ray diffraction and spectroscopy beamline at the Brazilian Synchrotron Light Laboratory for performing total scattering experiments to be analyzed by atomic pair distribution function (PDF) studies. The results of a PDF refinement for Al2O3 standard are presented and compared with data acquired at a beamline of the Advanced Photon Source, where it is common to perform this type of experiment. A preliminary characterization of the Pb1 – xLaxZr0.40Ti0.60O3 ferroelectric system, with x = 0.11, 0.12 and 0.15, is also shown. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - July 28, 2017 Category: Physics Authors: Saleta, M.E. Eleot é rio, M. Mesquita, A. Mastelaro, V.R. Granado, E. Tags: atomic pair distribution function X-ray total scattering ferroelectric relaxor beamlines Source Type: research

Temperature-dependent thermal properties of Ru/C multilayers
Multilayers made of Ru/C are the most promising candidates when working in the energy region 8 – 20   keV. The stability of its thermal properties, including thermal expansion and thermal conduction, needs to be considered for monochromator or focusing components. Ru/C multilayers with periodic thicknesses of 3, 4 and 5   nm were investigated in   situ by grazing-incidence X-ray reflectometry and diffuse scattering in order to study their thermal expansion characteristics as a function of annealing temperature up to 400 ° C. The thermal conductivity of multilayers with the same structure was also measured b...
Source: Journal of Synchrotron Radiation - July 28, 2017 Category: Physics Authors: Yan S. Jiang, H. Wang, H. He, Y. Li, A. Zheng, Y. Dong, Z. Tian, N. Tags: multilayer X-ray interface thermal conductivity research papers Source Type: research

Phase-merging enhanced harmonic generation free-electron laser with a normal modulator
A phase-merging enhanced harmonic generation free-electron laser (FEL) was proposed to increase the harmonic conversion efficiency of seeded FELs and promote the radiation wavelength towards the X-ray spectral region. However, this requires a specially designed transverse gradient undulator (TGU) as the modulator to couple the transverse and longitudinal phase space of the electron beam. In this paper, the generation of the phase-merging effect is explored using the natural field gradient of a normal planar undulator. In this method, a vertical dispersion on the electron beam is introduced and then the dispersed beam trave...
Source: Journal of Synchrotron Radiation - July 28, 2017 Category: Physics Authors: Zhao, Z. Li, H. Jia, Q. Tags: free-electron laser phase-merging effect natural transverse gradient beam orbit offset research papers Source Type: research

Current events
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - June 29, 2017 Category: Physics Authors: , Tags: current events Source Type: research

The relativistic foundations of synchrotron radiation
Special relativity (SR) determines the properties of synchrotron radiation, but the corresponding mechanisms are frequently misunderstood. Time dilation is often invoked among the causes, whereas its role would violate the principles of SR. Here it is shown that the correct explanation of the synchrotron radiation properties is provided by a combination of the Doppler shift, not dependent on time dilation effects, contrary to a common belief, and of the Lorentz transformation into the particle reference frame of the electromagnetic field of the emission-inducing device, also with no contribution from time dilation. Conclud...
Source: Journal of Synchrotron Radiation - June 20, 2017 Category: Physics Authors: Margaritondo, G. Rafelski, J. Tags: special relativity Doppler time dilation Lorentz transformation teaching and education Source Type: research

Accuracy of stress measurement by Laue microdiffraction (Laue-DIC method): the influence of image noise, calibration errors and spot number
Laue microdiffraction, available at several synchrotron radiation facilities, is well suited for measuring the intragranular stress field in deformed materials thanks to the achievable submicrometer beam size. The traditional method for extracting elastic strain (and hence stress) and lattice orientation from a microdiffraction image relies on fitting each Laue spot with an analytical function to estimate the peak position on the detector screen. The method is thus limited to spots exhibiting ellipsoidal shapes, thereby impeding the study of specimens plastically deformed. To overcome this difficulty, the so-called Laue-DI...
Source: Journal of Synchrotron Radiation - June 20, 2017 Category: Physics Authors: Zhang, F.G. Bornert, M. Petit, J. Castelnau, O. Tags: Laue microdiffraction image noise digital image correlation stress analysis research papers Source Type: research

Rotatable high-resolution ARPES system for tunable linear-polarization geometry
A rotatable high-resolution angle-resolved photoemission spectroscopy (ARPES) system has been developed to utilize tunable linear-polarization geometries on the linear undulator beamline (BL-1) at Hiroshima Synchrotron Radiation Center. By rotating the whole ARPES measurement system, the photoelectron detection plane can be continuously changed from parallel to normal against the electric field vector of linearly polarized undulator radiation. This polarization tunability enables us to identify the symmetry of the initial electronic states with respect to the mirror planes, and to selectively observe the electronic states ...
Source: Journal of Synchrotron Radiation - June 19, 2017 Category: Physics Authors: Iwasawa, H. Shimada, K. Schwier, E.F. Zheng, M. Kojima, Y. Hayashi, H. Jiang, J. Higashiguchi, M. Aiura, Y. Namatame, H. Taniguchi, M. Tags: angle-resolved photoemission spectroscopy (ARPES) rotatable high-resolution ARPES system linear polarization condensed-matter physics research papers Source Type: research

Pump − probe experiments at the TEMPO beamline using the low- α operation mode of Synchrotron SOLEIL
The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump – probe experiments. Among others, the low- α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50   ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low- α mode of the experimental set-ups developed at the TEMPO beamline to perform pump – probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282   kHz repetition-rate femtosecond laser is synchronized with the synchrotron rad...
Source: Journal of Synchrotron Radiation - June 15, 2017 Category: Physics Authors: Silly, M.G. Fert é , T. Tordeux, M.A. Pierucci, D. Beaulieu, N. Chauvet, C. Pressacco, F. Sirotti, F. Popescu, H. Lopez-Flores, V. Tortarolo, M. Sacchi, M. Jaouen, N. Hollander, P. Ricaud, J.P. Bergeard, N. Boeglin, C. Tudu, B. Delaunay, R. Luning, J. Ma Tags: time-resolved spectroscopy pump – probe experiments beamlines Source Type: research

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source
Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribu...
Source: Journal of Synchrotron Radiation - June 15, 2017 Category: Physics Authors: Pardini, T. Aquila, A. Boutet, S. Cocco, D. Hau-Riege, S.P. Tags: XFEL LCLS wavefront propagation simulations X-ray optics research papers Source Type: research

Protective radiolucent aluminium oxide coatings for   beryllium X-ray optics
Beryllium, being one of the most transparent materials to X-ray radiation, has become the material of choice for X-ray optics instrumentation at synchrotron radiation sources and free-electron laser facilities. However, there are concerns due to its high toxicity and, consequently, there is a need for special safety regulations. The authors propose to apply protective coatings in order to seal off beryllium from the ambient atmosphere, thus preventing degradation processes providing additional protection for users and prolonging the service time of the optical elements. This paper presents durability test results for Be wi...
Source: Journal of Synchrotron Radiation - June 15, 2017 Category: Physics Authors: Yurkevich, O. Maksimova, K. Goikhman, A. Grunin, A. Prokopovich, P. Tyurin, A. Medvedskaya, P. Lyatun, I. Snigireva, I. Snigirev, A. Tags: beryllium optics protective coatings aluminium oxide research papers Source Type: research

X-ray reflectivity measurement of interdiffusion in   metallic multilayers during rapid heating
A technique for measuring interdiffusion in multilayer materials during rapid heating using X-ray reflectivity is described. In this technique the sample is bent to achieve a range of incident angles simultaneously, and the scattered intensity is recorded on a fast high-dynamic-range mixed-mode pixel array detector. Heating of the multilayer is achieved by electrical resistive heating of the silicon substrate, monitored by an infrared pyrometer. As an example, reflectivity data from Al/Ni heated at rates up to 200   K   s − 1 are presented. At short times the interdiffusion coefficient can be determined from the ...
Source: Journal of Synchrotron Radiation - June 15, 2017 Category: Physics Authors: Liu, J.P. Kirchhoff, J. Zhou, L. Zhao, M. Grapes, M.D. Dale, D.S. Tate, M.D. Philipp, H.T. Gruner, S.M. Weihs, T.P. Hufnagel, T.C. Tags: X-ray reflectivity multilayer interdiffusion research papers Source Type: research

Effects of temperature, mechanical motion and source positional jitter on the resolving power of beamline 02B at the SSRF
A detailed analysis of the effects of temperature excursions, instrumental mechanical motion and source position jitter on the energy-resolving power of beamline 02B at the Shanghai Synchrotron Radiation Facility (SSRF) is presented in this study. This beamline uses a bending-magnet-based source and includes a variable-line-spacing grating monochromator with additional optics. Expressions are derived for the monochromator output photon energy shifts for each of the performance challenges considered. The calculated results indicate that measured temperature excursions of ± 1   K produce an energy shift of less than...
Source: Journal of Synchrotron Radiation - June 14, 2017 Category: Physics Authors: Guo, Z. Meng, X. Wang, Y. Liu, H. Zhang, X. Li, Z. Xue, L. Tai, R. Tags: variable-line-spacing grating mechanical vibration source positional jitter energy-resolving power beamlines Source Type: research

Three-dimensional reconstruction for coherent diffraction patterns obtained by XFEL
The three-dimensional (3D) structural analysis of single particles using an X-ray free-electron laser (XFEL) is a new structural biology technique that enables observations of molecules that are difficult to crystallize, such as flexible biomolecular complexes and living tissue in the state close to physiological conditions. In order to restore the 3D structure from the diffraction patterns obtained by the XFEL, computational algorithms are necessary as the orientation of the incident beam with respect to the sample needs to be estimated. A program package for XFEL single-particle analysis based on the Xmipp software packa...
Source: Journal of Synchrotron Radiation - June 14, 2017 Category: Physics Authors: Nakano, M. Miyashita, O. Jonic, S. Song, C. Nam, D. Joti, Y. Tama, F. Tags: three-dimensional reconstruction single-particle analysis X-ray free-electron laser coherent X-ray diffraction imaging research papers Source Type: research

Normal tracing deflectometry using a secondary light source
Scanning deflectometric profilers based on an f – θ system are typical optical tools used to measure mirror profiles at many synchrotron facilities. Unlike these profilers, which are based on a pencil beam, here a secondary light source and a pinhole are used to construct a system that automatically selects a beam that will always pass through the pinhole and propagate along the normal direction of the measured area on the surface under test. By measuring the angle variation of the selected beam, slope variations of the surface under test can be measured. Systematic errors introduced by manufacturing defects or...
Source: Journal of Synchrotron Radiation - June 14, 2017 Category: Physics Authors: Peng, C.Q. He, Y.M. Wang, J. Tags: normal tracing method secondary light source deflectometric profiler beam lateral motion aberration inhomogeneity research papers Source Type: research

Structural variation in a synchrotron-induced contamination layer (a-C:H) deposited on a toroidal Au mirror surface
A carbon layer deposited on an optical component is the result of complex interactions between the optical surface, adsorbed hydrocarbons, photons and secondary electrons (photoelectrons generated on the surface of optical elements). In the present study a synchrotron-induced contamination layer on a 340   mm × 60   mm Au-coated toroidal mirror has been characterized. The contamination layer showed a strong variation in structural properties from the centre of the mirror to the edge region (along the long dimension of the mirror) due to the Gaussian distribution of the incident photon beam intensity/power on the ...
Source: Journal of Synchrotron Radiation - June 13, 2017 Category: Physics Authors: Yadav, P.K. Gupta, R.K. Swami, M.K. Modi, M.H. Tags: reflectivity Raman spectroscopy X-ray diffraction hydrogenerated carbon research papers Source Type: research

Very efficient spin polarization analysis (VESPA): new exchange scattering-based setup for spin-resolved ARPES at APE-NFFA beamline at Elettra
Complete photoemission experiments, enabling measurement of the full quantum set of the photoelectron final state, are in high demand for studying materials and nanostructures whose properties are determined by strong electron and spin correlations. Here the implementation of the new spin polarimeter VESPA (Very Efficient Spin Polarization Analysis) at the APE-NFFA beamline at Elettra is reported, which is based on the exchange coupling between the photoelectron spin and a ferromagnetic surface in a reflectometry setup. The system was designed to be integrated with a dedicated Scienta-Omicron DA30 electron energy analyzer ...
Source: Journal of Synchrotron Radiation - June 13, 2017 Category: Physics Authors: Bigi, C. Das, P.K. Benedetti, D. Salvador, F. Krizmancic, D. Sergo, R. Martin, A. Panaccione, G. Rossi, G. Fujii, J. Vobornik, I. Tags: spin-resolved ARPES VLEED polarimeter research papers Source Type: research

Using refractive optics to broaden the focus of an X-ray mirror
X-ray mirrors are widely used at synchrotron radiation sources for focusing X-rays into focal spots of size less than 1   µ m. The ability of the beamline optics to change the size of this spot over a range up to tens of micrometres can be an advantage for many experiments such as X-ray microprobe and X-ray diffraction from micrometre-scale crystals. It is a requirement that the beam size change should be reproducible and it is often essential that the change should be rapid, for example taking less than 1   s, in order to allow high data collection rates at modern X-ray sources. In order to provide a controlled ...
Source: Journal of Synchrotron Radiation - May 30, 2017 Category: Physics Authors: Laundy, D. Sawhney, K. Dhamgaye, V. Tags: X-ray focusing refractive optics research papers Source Type: research

In situ electrochemical high-energy X-ray diffraction using a capillary working electrode cell geometry
The ability to generate new electrochemically active materials for energy generation and storage with improved properties will likely be derived from an understanding of atomic-scale structure/function relationships during electrochemical events. Here, the design and implementation of a new capillary electrochemical cell designed specifically for in situ high-energy X-ray diffraction measurements is described. By increasing the amount of electrochemically active material in the X-ray path while implementing low-Z cell materials with anisotropic scattering profiles, an order of magnitude enhancement in diffracted X-ray sign...
Source: Journal of Synchrotron Radiation - May 26, 2017 Category: Physics Authors: Young, M.J. Bedford, N.M. Jiang, N. Lin, D. Dai, L. Tags: electrochemistry atomic structure flow cell nanoparticles pair distribution function research papers Source Type: research

A method to stabilize the incident X-ray energy for anomalous diffraction measurements
A method to calibrate and stabilize the incident X-ray energy for anomalous diffraction data collection is provided and has been successfully used at the single-crystal diffraction beamline 1W2B at the Beijing Synchrotron Radiation Facilities. Employing a feedback loop to control the movement of the double-crystal monochromator, this new method enables the incident X-ray energy to be kept within a 0.2   eV range at the inflection point of the absorption edge. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - May 19, 2017 Category: Physics Authors: Wang, W. Yang, X. Chang, G. An, P. Cha, K. Dong, Y. Liu, P. Tags: energy stability monochromator anomalous diffraction feedback absorption edge. research papers Source Type: research

Insight into growth of Au – Pt bimetallic nanoparticles: an in   situ XAS study
Au – Pt bimetallic nanoparticles have been synthesized through a one-pot synthesis route from their respective chloride precursors using block copolymer as a stabilizer. Growth of the nanoparticles has been studied by simultaneous in   situ measurement of X-ray absorption spectroscopy (XAS) and UV – Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at Indus-2 SRS at RRCAT, Indore, India. In   situ XAS spectra, comprising both X-ray near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) parts, have been measured simultaneously at the Au and Pt L3-edges. While th...
Source: Journal of Synchrotron Radiation - May 18, 2017 Category: Physics Authors: Nayak, C. Bhattacharyya, D. Bhattacharyya, K. Tripathi, A.K. Bapat, R.D. Jha, S.N. Sahoo, N.K. Tags: XAS in   situ EXAFS XANES core – shell research papers Source Type: research

Comparison of phantom materials for use in quality assurance of microbeam radiation therapy
Microbeam radiation therapy (MRT) is a promising radiotherapy modality that uses arrays of spatially fractionated micrometre-sized beams of synchrotron radiation to irradiate tumours. Routine dosimetry quality assurance (QA) prior to treatment is necessary to identify any changes in beam condition from the treatment plan, and is undertaken using solid homogeneous phantoms. Solid phantoms are designed for, and routinely used in, megavoltage X-ray beam radiation therapy. These solid phantoms are not necessarily designed to be water-equivalent at low X-ray energies, and therefore may not be suitable for MRT QA. This work quan...
Source: Journal of Synchrotron Radiation - May 18, 2017 Category: Physics Authors: Cameron, M. Cornelius, I. Cutajar, D. Davis, J. Rosenfeld, A. Lerch, M. Guatelli, S. Tags: microbeam radiation therapy polymer phantoms dosimetry Monte Carlo Geant4 research papers Source Type: research

Preclinical radiotherapy at the Australian Synchrotron's Imaging and Medical Beamline: instrumentation, dosimetry and a small-animal feasibility study
Therapeutic applications of synchrotron X-rays such as microbeam (MRT) and minibeam (MBRT) radiation therapy promise significant advantages over conventional clinical techniques for some diseases if successfully transferred to clinical practice. Preclinical studies show clear evidence that a number of normal tissues in animal models display a tolerance to much higher doses from MRT compared with conventional radiotherapy. However, a wide spread in the parameters studied makes it difficult to make any conclusions about the associated tumour control or normal tissue complication probabilities. To facilitate more systematic a...
Source: Journal of Synchrotron Radiation - May 17, 2017 Category: Physics Authors: Livingstone, J. Adam, J.F. Crosbie, J.C. Hall, C.J. Lye, J.E. McKinlay, J. Pelliccia, D. Pouzoulet, F. Prezado, Y. Stevenson, A.W. H ä usermann, D. Tags: radiotherapy preclinical dosimetry imaging research papers Source Type: research

Alternative difference analysis scheme combining R-space EXAFS fit with global optimization XANES fit for X-ray transient absorption spectroscopy
Time-resolved X-ray absorption spectroscopy (TR-XAS), based on the laser-pump/X-ray-probe method, is powerful in capturing the change of the geometrical and electronic structure of the absorbing atom upon excitation. TR-XAS data analysis is generally performed on the laser-on minus laser-off difference spectrum. Here, a new analysis scheme is presented for the TR-XAS difference fitting in both the extended X-ray absorption fine-structure (EXAFS) and the X-ray absorption near-edge structure (XANES) regions. R-space EXAFS difference fitting could quickly provide the main quantitative structure change of the first shell. The ...
Source: Journal of Synchrotron Radiation - May 17, 2017 Category: Physics Authors: Zhan, F. Tao, Y. Zhao, H. Tags: difference XAFS fit global optimization R-space core/shell substitution TR-XAS research papers Source Type: research

Potential of propagation-based synchrotron X-ray phase-contrast computed tomography for cardiac tissue engineering
Hydrogel-based cardiac tissue engineering offers great promise for myocardial infarction repair. The ability to visualize engineered systems in vivo in animal models is desired to monitor the performance of cardiac constructs. However, due to the low density and weak X-ray attenuation of hydrogels, conventional radiography and micro-computed tomography are unable to visualize the hydrogel cardiac constructs upon their implantation, thus limiting their use in animal systems. This paper presents a study on the optimization of synchrotron X-ray propagation-based phase-contrast imaging computed tomography (PCI-CT) for three-di...
Source: Journal of Synchrotron Radiation - May 17, 2017 Category: Physics Authors: Izadifar, M. Babyn, P. Chapman, D. Kelly, M.E. Chen, X. Tags: cardiac patch computed tomography hydrogel phase-contrast imaging tissue engineering research papers Source Type: research

Current events
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 28, 2017 Category: Physics Authors: , Tags: current events Source Type: research

Understanding the instrumental profile of synchrotron radiation X-ray powder diffraction beamlines
A Monte Carlo algorithm has been developed to calculate the instrumental profile function of a powder diffraction synchrotron beamline. Realistic models of all optical elements are implemented in a ray-tracing software. The proposed approach and the emerging paradigm have been investigated and verified for several existing X-ray powder diffraction beamlines. The results, which can be extended to further facilities, show a new and general way of assessing the contribution of instrumental broadening to synchrotron radiation data, based on ab   initio simulations. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - April 20, 2017 Category: Physics Authors: Rebuffi, L. S á nchez del R í o, M. Busetto, E. Scardi, P. Tags: ray-tracing powder diffraction instrumental profile function simulation research papers Source Type: research

Long, elliptically bent, active X-ray mirrors with slope errors < 200   nrad
Actively bent X-ray mirrors are important components of many synchrotron and X-ray free-electron laser beamlines. A high-quality optical surface and good bending performance are essential to ensure that the X-ray beam is accurately focused. Two elliptically bent X-ray mirror systems from FMB Oxford were characterized in the optical metrology laboratory at Diamond Light Source. A comparison of Diamond-NOM slope profilometry and finite-element analysis is presented to investigate how the 900   mm-long mirrors sag under gravity, and how this deformation can be adequately compensated using a single, spring-loaded compensator...
Source: Journal of Synchrotron Radiation - April 19, 2017 Category: Physics Authors: Nistea, I.T. Alcock, S.G. Kristiansen, P. Young, A. Tags: X-ray active optics mechanically bent mirrors optical metrology Diamond-NOM research papers Source Type: research

Fluid dynamics analysis of a gas attenuator for X-ray FELs under high-repetition-rate operation
Newtonian fluid dynamics simulations were performed using the Navier – Stokes – Fourier formulations to elucidate the short time-scale ( µ s and longer) evolution of the density and temperature distributions in an argon-gas-filled attenuator for an X-ray free-electron laser under high-repetition-rate operation. Both hydrodynamic motions of the gas molecules and thermal conductions were included in a finite-volume calculation. It was found that the hydrodynamic wave motions play the primary role in creating a density depression (also known as a filament) by advectively transporting gas particles away from ...
Source: Journal of Synchrotron Radiation - April 18, 2017 Category: Physics Authors: Yang, B. Wu, J. Raubenheimer, T.O. Feng, Y. Tags: filamentation X-ray FEL attenuation gas fluid dynamics thermal conduction research papers Source Type: research

Time-resolved XAFS measurement using quick-scanning techniques at BSRF
A new quick-scanning X-ray absorption fine-structure (QXAFS) system has been established on beamline 1W1B at the Beijing Synchrotron Radiation Facility. As an independent device, the QXAFS system can be employed by other beamlines equipped with a double-crystal monochromator to carry out quick energy scans and data acquisition. Both continuous-scan and trapezoidal-scan modes are available in this system to satisfy the time scale from subsecond (in the X-ray absorption near-edge structure region) to 1   min. Here, the trapezoidal-scan method is presented as being complementary to the continuous-scan method, in order to ma...
Source: Journal of Synchrotron Radiation - April 12, 2017 Category: Physics Authors: Chu, S. Zheng, L. An, P. Gong, H. Hu, T. Xie, Y. Zhang, J. Tags: time-resolved XAFS QXAFS 1W1B BSRF research papers Source Type: research

Effective aperture of X-ray compound refractive lenses
A new definition of the effective aperture of the X-ray compound refractive lens (CRL) is proposed. Both linear (one-dimensional) and circular (two-dimensional) CRLs are considered. It is shown that for a strongly absorbing CRL the real aperture does not influence the focusing properties and the effective aperture is determined by absorption. However, there are three ways to determine the effective aperture in terms of transparent CRLs. In the papers by Kohn [(2002). JETP Lett. 76, 600 – 603; (2003). J. Exp. Theor. Phys. 97, 204 – 215; (2009). J. Surface Investig. 3, 358 – 364; (2012). J. Synchrotron Rad....
Source: Journal of Synchrotron Radiation - April 12, 2017 Category: Physics Authors: Kohn, V.G. Tags: X-ray focusing theory compound refractive lens effective aperture X-ray absorption computer simulations research papers Source Type: research