x UX Design Methods In A Mind Map By sidebar.io Published On :: Sun, 10 May 2020 05:30:07 GMT If you are wondering when to apply which design methods, this mind map may help you. Full Article
x Exclusive App for Webinars - UI UX Case Study By sidebar.io Published On :: Sun, 10 May 2020 05:31:37 GMT This case study is part of a design challenge in which I was asked to explore live streaming as a media format. Full Article
x This week's sponsor: ADOBE XD By feedproxy.google.com Published On :: 2016-11-14T05:01:00+00:00 ADOBE XD BETA, the only all-in-one solution for designing, prototyping, and sharing experiences for websites and mobile apps. Full Article
x India’s fuel consumption dips 46 per cent in April; expected to rebound in May By www.thehindubusinessline.com Published On :: Sun, 10 May 2020 12:21:31 +0530 Petrol sales were down 60.43 per cent to 9,73,000 tonnes in April Full Article Economy
x Stimulus package likely next week; Guaranteed higher working capital limit for MSME on cards By www.thehindubusinessline.com Published On :: Sat, 09 May 2020 22:34:47 +0530 Centre plans to raise the total borrowings to ₹12 lakh crore this fiscal Full Article Economy
x Cochin Port Trust helps during ‘Operation Samudra Sethu’ for Maldives expatriates By www.thehindubusinessline.com Published On :: Sun, 10 May 2020 11:55:50 +0530 This is the Indian Navy’s first massive evacuation exercise during the Covid-19 lockdown Full Article National
x Your Taxes By www.thehindubusinessline.com Published On :: Sun, 10 May 2020 12:10:14 +0530 I retired from LIC on April 30, 2019. All my tax dues (salary) were recovered from my final payments in May 2019. I had opened an NSS 87 account with Full Article Personal Finance
x Should rental income earners shift to the new tax regime? By www.thehindubusinessline.com Published On :: Sun, 10 May 2020 12:13:32 +0530 Be wise when it comes to opting for the tax regime from this year Full Article Personal Finance
x Hydroxychloroquine drug fails another test to prove efficiency in treating COVID-19 By www.dnaindia.com Published On :: Sun, 10 May 2020 02:48:00 GMT The study, however, concluded that HCQ had no potential harm either. Full Article World
x DNA Exclusive: Arti Singh remembers how her first letter to mother brought them closer By www.dnaindia.com Published On :: Sun, 10 May 2020 05:23:00 GMT Arti Singh remembered her first letter to mother on the occasion of Mothers' Day Full Article Entertainment Television
x DNA Exclusive: Sophie Choudry reveals how she would celebrate Mothers' Day with 'super mom' By www.dnaindia.com Published On :: Sun, 10 May 2020 05:40:00 GMT The coronavirus lockdown has separated many of us from our families, including our mothers. However, Sophie Choudhry is one lucky celeb who is able to spend her quarantine and Mothers' Day with her supermom. In fact, she told us all about her plans for the day. Full Article Entertainment Bollywood
x 'Famotidine may become the next HCQ for Covid-19' By www.rediff.com Published On :: Sun, 10 May 2020 10:39:32 +0530 Researchers at Northwell Health in New York are testing the effects on Famotidine (used in high intravenous doses) on Covid-19 patients as a potential treatment. After the hospital announced its clinical trials, it led to a drug shortage in the US. Back home, however, there has not been any surge in the demand for Famotidine yet. Full Article
x Netflix’s Mother’s Day watchlist: Lady Bird, Roma and others By indianexpress.com Published On :: Sun, 10 May 2020 04:55:32 +0000 Full Article Entertainment Web series
x Inside Track: Kishor’s expertise By indianexpress.com Published On :: Sat, 09 May 2020 18:46:34 +0000 Full Article Columns Opinion
x Chandigarh extends excise policy till June 30 By timesofindia.indiatimes.com Published On :: Sun, 10 May 2020 06:04:08 IST The UT excise and taxation department has extended the excise policy from May 15 to June 30 due to the Covid-19 pandemic and the ongoing lockdown. Full Article
x Indian women’s archery team to get final chance at Olympic quota in June next year By indianexpress.com Published On :: Sat, 09 May 2020 15:41:27 +0000 Full Article Sport Others Sports
x Shraddha Kapoor’s airport looks mirror the ‘girl next door’ theme By indianexpress.com Published On :: Sat, 09 May 2020 14:19:19 +0000 Full Article
x Crossing final hurdle in World Cups down to experience and preparation: Anjum Chopra By indianexpress.com Published On :: Sat, 09 May 2020 14:35:48 +0000 Full Article Cricket Sports
x Device for source position stabilization and beam parameter monitoring at inverse Compton X-ray sources By scripts.iucr.org Published On :: 2019-08-07 Compact X-ray sources based on inverse Compton scattering provide brilliant and partially coherent X-rays in a laboratory environment. The cross section for inverse Compton scattering is very small, requiring high-power laser systems as well as small laser and electron beam sizes at the interaction point to generate sufficient flux. Therefore, these systems are very sensitive to distortions which change the overlap between the two beams. In order to monitor X-ray source position, size and flux in parallel to experiments, the beam-position monitor proposed here comprises a small knife edge whose image is acquired with an X-ray camera specifically designed to intercept only a very small fraction of the X-ray beam. Based on the source position drift recorded with the monitor, a closed-loop feedback stabilizes the X-ray source position by adjusting the laser beam trajectory. A decrease of long-term source position drifts by more than one order of magnitude is demonstrated with this device. Consequently, such a closed-loop feedback system which enables stabilization of source position drifts and flux of inverse Compton sources in parallel to experiments has a significant impact on the performance of these sources. Full Article text
x A versatile nanoreactor for complementary in situ X-ray and electron microscopy studies in catalysis and materials science By scripts.iucr.org Published On :: 2019-08-27 Two in situ `nanoreactors' for high-resolution imaging of catalysts have been designed and applied at the hard X-ray nanoprobe endstation at beamline P06 of the PETRA III synchrotron radiation source. The reactors house samples supported on commercial MEMS chips, and were applied for complementary hard X-ray ptychography (23 nm spatial resolution) and transmission electron microscopy, with additional X-ray fluorescence measurements. The reactors allow pressures of 100 kPa and temperatures of up to 1573 K, offering a wide range of conditions relevant for catalysis. Ptychographic tomography was demonstrated at limited tilting angles of at least ±35° within the reactors and ±65° on the naked sample holders. Two case studies were selected to demonstrate the functionality of the reactors: (i) annealing of hierarchical nanoporous gold up to 923 K under inert He environment and (ii) acquisition of a ptychographic projection series at ±35° of a hierarchically structured macroporous zeolite sample under ambient conditions. The reactors are shown to be a flexible and modular platform for in situ studies in catalysis and materials science which may be adapted for a range of sample and experiment types, opening new characterization pathways in correlative multimodal in situ analysis of functional materials at work. The cells will presently be made available for all interested users of beamline P06 at PETRA III. Full Article text
x Scientific instrument Femtosecond X-ray Experiments (FXE): instrumentation and baseline experimental capabilities By scripts.iucr.org Published On :: 2019-08-09 The European X-ray Free-Electron Laser (EuXFEL) delivers extremely intense (>1012 photons pulse−1 and up to 27000 pulses s−1), ultrashort (<100 fs) and transversely coherent X-ray radiation, at a repetition rate of up to 4.5 MHz. Its unique X-ray beam parameters enable novel and groundbreaking experiments in ultrafast photochemistry and material sciences at the Femtosecond X-ray Experiments (FXE) scientific instrument. This paper provides an overview of the currently implemented experimental baseline instrumentation and its performance during the commissioning phase, and a preview of planned improvements. FXE's versatile instrumentation combines the simultaneous application of forward X-ray scattering and X-ray spectroscopy techniques with femtosecond time resolution. These methods will eventually permit exploitation of wide-angle X-ray scattering studies and X-ray emission spectroscopy, along with X-ray absorption spectroscopy, including resonant inelastic X-ray scattering and X-ray Raman scattering. A suite of ultrafast optical lasers throughout the UV–visible and near-IR ranges (extending up to mid-IR in the near future) with pulse length down to 15 fs, synchronized to the X-ray source, serve to initiate dynamic changes in the sample. Time-delayed hard X-ray pulses in the 5–20 keV range are used to probe the ensuing dynamic processes using the suite of X-ray probe tools. FXE is equipped with a primary monochromator, a primary and secondary single-shot spectrometer, and a timing tool to correct the residual timing jitter between laser and X-ray pulses. Full Article text
x Low-dose X-ray structure analysis of cytochrome c oxidase utilizing high-energy X-rays By scripts.iucr.org Published On :: 2019-06-14 To investigate the effect of high-energy X-rays on site-specific radiation-damage, low-dose diffraction data were collected from radiation-sensitive crystals of the metal enzyme cytochrome c oxidase. Data were collected at the Structural Biology I beamline (BL41XU) at SPring-8, using 30 keV X-rays and a highly sensitive pixel array detector equipped with a cadmium telluride sensor. The experimental setup of continuous sample translation using multiple crystals allowed the average diffraction weighted dose per data set to be reduced to 58 kGy, and the resulting data revealed a ligand structure featuring an identical bond length to that in the damage-free structure determined using an X-ray free-electron laser. However, precise analysis of the residual density around the ligand structure refined with the synchrotron data showed the possibility of a small level of specific damage, which might have resulted from the accumulated dose of 58 kGy per data set. Further investigation of the photon-energy dependence of specific damage, as assessed by variations in UV-vis absorption spectra, was conducted using an on-line spectrometer at various energies ranging from 10 to 30 keV. No evidence was found for specific radiation damage being energy dependent. Full Article text
x Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction By scripts.iucr.org Published On :: 2019-07-19 Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time. Full Article text
x Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering By scripts.iucr.org Published On :: 2019-08-09 Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode. Full Article text
x X-ray reflecto-interferometer based on compound refractive lenses By scripts.iucr.org Published On :: 2019-08-12 An X-ray amplitude-splitting interferometer based on compound refractive lenses, which operates in the reflection mode, is proposed and realized. The idea of a reflecto-interferometer is to use a very simplified experimental setup where a focused X-ray beam reflected from parallel flat surfaces creates an interference pattern in a wide angular range. The functional capabilities of the interferometer were experimentally tested at the European Synchrotron Radiation Facility (ESRF) ID06 beamline in the X-ray energy range from 10 keV to 15 keV. The main features of the proposed approach, high spatial and temporal resolution, were demonstrated experimentally. The reflections from free-standing Si3N4 membranes, gold and resist layers were studied. Experimentally recorded interferograms are in good agreement with our simulations. The main advantages and future possible applications of the reflecto-interferometer are discussed. Full Article text
x Soft X-ray varied-line-spacing gratings fabricated by near-field holography using an electron beam lithography-written phase mask By scripts.iucr.org Published On :: 2019-08-16 A fabrication method comprising near-field holography (NFH) with an electron beam lithography (EBL)-written phase mask was developed to fabricate soft X-ray varied-line-spacing gratings (VLSGs). An EBL-written phase mask with an area of 52 mm × 30 mm and a central line density greater than 3000 lines mm−1 was used. The introduction of the EBL-written phase mask substantially simplified the NFH optics for pattern transfer. The characterization of the groove density distribution and diffraction efficiency of the fabricated VLSGs indicates that the EBL–NFH method is feasible and promising for achieving high-accuracy groove density distributions with corresponding image properties. Vertical stray light is suppressed in the soft X-ray spectral range. Full Article text
x Microsecond time-resolved X-ray diffraction for the investigation of fatigue behavior during ultrasonic fatigue loading By scripts.iucr.org Published On :: 2019-08-20 A new method based on time-resolved X-ray diffraction is proposed in order to measure the elastic strain and stress during ultrasonic fatigue loading experiments. Pure Cu was chosen as an example material for the experiments using a 20 kHz ultrasonic fatigue machine mounted on the six-circle diffractometer available at the DiffAbs beamline on the SOLEIL synchrotron facility in France. A two-dimensional hybrid pixel X-ray detector (XPAD3.2) was triggered by the strain gage signal in a synchronous data acquisition scheme (pump–probe-like). The method enables studying loading cycles with a period of 50 µs, achieving a temporal resolution of 1 µs. This allows a precise reconstruction of the diffraction patterns during the loading cycles. From the diffraction patterns, the position of the peaks, their shifts and their respective broadening can be deduced. The diffraction peak shift allows the elastic lattice strain to be estimated with a resolution of ∼10−5. Stress is calculated by the self-consistent scale-transition model through which the elastic response of the material is estimated. The amplitudes of the cyclic stresses range from 40 to 120 MPa and vary linearly with respect to the displacement applied by the ultrasonic machine. Moreover, the experimental results highlight an increase of the diffraction peak broadening with the number of applied cycles. Full Article text
x X-ray radiation damage to biological samples: recent progress By scripts.iucr.org Published On :: 2019-07-01 With the continuing development of beamlines for macromolecular crystallography (MX) over the last few years providing ever higher X-ray flux densities, it has become even more important to be aware of the effects of radiation damage on the resulting structures. Nine papers in this issue cover a range of aspects related to the physics and chemistry of the manifestations of this damage, as observed in both MX and small-angle X-ray scattering (SAXS) on crystals, solutions and tissue samples. The reports include measurements of the heating caused by X-ray irradiation in ruby microcrystals, low-dose experiments examining damage rates as a function of incident X-ray energy up to 30 keV on a metallo-enzyme using a CdTe detector of high quantum efficiency as well as a theoretical analysis of the gains predicted in diffraction efficiency using these detectors, a SAXS examination of low-dose radiation exposure effects on the dissociation of a protein complex related to human health, theoretical calculations describing radiation chemistry pathways which aim to explain the specific structural damage widely observed in proteins, investigation of radiation-induced damage effects in a DNA crystal, a case study on a metallo-enzyme where structural movements thought to be mechanism related might actually be radiation-damage-induced changes, and finally a review describing what X-ray radiation-induced cysteine modifications can teach us about protein dynamics and catalysis. These papers, along with some other relevant literature published since the last Journal of Synchrotron Radiation Radiation Damage special issue in 2017, are briefly summarized below. Full Article text
x Coherent Bragg imaging of 60 nm Au nanoparticles under electrochemical control at the NanoMAX beamline By scripts.iucr.org Published On :: 2019-08-27 Nanoparticles are essential electrocatalysts in chemical production, water treatment and energy conversion, but engineering efficient and specific catalysts requires understanding complex structure–reactivity relations. Recent experiments have shown that Bragg coherent diffraction imaging might be a powerful tool in this regard. The technique provides three-dimensional lattice strain fields from which surface reactivity maps can be inferred. However, all experiments published so far have investigated particles an order of magnitude larger than those used in practical applications. Studying smaller particles quickly becomes demanding as the diffracted intensity falls. Here, in situ nanodiffraction data from 60 nm Au nanoparticles under electrochemical control collected at the hard X-ray nanoprobe beamline of MAX IV, NanoMAX, are presented. Two-dimensional image reconstructions of these particles are produced, and it is estimated that NanoMAX, which is now open for general users, has the requisites for three-dimensional imaging of particles of a size relevant for catalytic applications. This represents the first demonstration of coherent X-ray diffraction experiments performed at a diffraction-limited storage ring, and illustrates the importance of these new sources for experiments where coherence properties become crucial. Full Article text
x An enlightening procedure to explain the extreme power of synchrotron radiation By scripts.iucr.org Published On :: 2019-10-10 A simple approach exploits quantum properties to justify the dependence on γ4 of the total synchrotron emitted power. It also clarifies some apparent puzzles and brings to light the underlying, multiple relativistic phenomena. Full Article text
x Performance of nearly fixed offset asymmetric channel-cut crystals for X-ray monochromators By scripts.iucr.org Published On :: 2019-10-16 X-ray double-crystal monochromators face a shift of the exit beam when the Bragg angle and thus the transmitted photon energy changes. This can be compensated for by moving one or both crystals accordingly. In the case of monolithic channel-cut crystals, which exhibit utmost stability, the shift of the monochromated beam is inevitable. Here we report performance tests of novel, asymmetrically cut, channel-cut crystals which reduce the beam movements by more than a factor of 20 relative to the symmetric case over the typical energy range of an EXAFS spectrum at the Cu K-edge. In addition, the presented formulas for the beam offset including the asymmetry angle directly indicate the importance of this value, which has been commonly neglected so far in the operation of double-crystal monochromators. Full Article text
x Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording By scripts.iucr.org Published On :: 2019-11-01 An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å−1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å−1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s−1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool. Full Article text
x Coherence properties of the high-energy fourth-generation X-ray synchrotron sources By scripts.iucr.org Published On :: 2019-11-01 An analysis of the coherence properties of the fourth-generation high-energy storage rings with emittance values of 10 pm rad is performed. It is presently expected that a storage ring with these low emittance values will reach diffraction limit at hard X-rays. Simulations of coherence properties were performed with the XRT software and an analytical approach for different photon energies from 500 eV to 50 keV. It was demonstrated that a minimum photon emittance (diffraction limit) reached at such storage rings is λ/2π. Using mode decomposition it is shown that, for the parameters of the storage ring considered in this work, the diffraction limit will be reached for soft X-ray energies of 500 eV. About ten modes will contribute to the radiation field at 12 keV photon energy and even more modes give a contribution at higher photon energies. Energy spread effects of the electron beam in a low-emittance storage ring were analysed in detail. Simulations were performed at different relative energy spread values from zero to 2 × 10−3. A decrease of the degree of coherence with an increase of the relative energy spread value was observed. This analysis shows that, to reach the diffraction limit for high photon energies, electron beam emittance should go down to 1 pm rad and below. Full Article text
x A von Hamos-type hard X-ray spectrometer at the PETRA III beamline P64 By scripts.iucr.org Published On :: 2020-01-01 The design and performance of the high-resolution wavelength-dispersive multi-crystal von Hamos-type spectrometer at PETRA III beamline P64 are described. Extended analyzer crystal collection available at the beamline allows coverage of a broad energy range from 5 keV to 20 keV with an energy resolution of 0.35–1 eV. Particular attention was paid to enabling two-color measurements by a combination of two types of analyzer crystals and two two-dimensional detectors. The performance of the spectrometer is demonstrated by elastic-line and emission-line measurements on various compounds. Full Article text
x X-ray fluorescence analysis of metal distributions in cryogenic biological samples using large-acceptance-angle SDD detection and continuous scanning at the Hard X-ray Micro/Nano-Probe beamline P06 at PETRA III By scripts.iucr.org Published On :: 2020-01-01 A new Rococo 2 X-ray fluorescence detector was implemented into the cryogenic sample environment at the Hard X-ray Micro/Nano-Probe beamline P06 at PETRA III, DESY, Hamburg, Germany. A four sensor-field cloverleaf design is optimized for the investigation of planar samples and operates in a backscattering geometry resulting in a large solid angle of up to 1.1 steradian. The detector, coupled with the Xspress 3 pulse processor, enables measurements at high count rates of up to 106 counts per second per sensor. The measured energy resolution of ∼129 eV (Mn Kα at 10000 counts s−1) is only minimally impaired at the highest count rates. The resulting high detection sensitivity allows for an accurate determination of trace element distributions such as in thin frozen hydrated biological specimens. First proof-of-principle measurements using continuous-movement 2D scans of frozen hydrated HeLa cells as a model system are reported to demonstrate the potential of the new detection system. Full Article text
x XUV-driven plasma switch for THz: new spatio-temporal overlap tool for XUV–THz pump–probe experiments at FELs By scripts.iucr.org Published On :: 2020-01-01 A simple and robust tool for spatio-temporal overlap of THz and XUV pulses in in-vacuum pump–probe experiments is presented. The technique exploits ultrafast changes of the optical properties in semiconductors (i.e. silicon) driven by ultrashort XUV pulses that are probed by THz pulses. This work demonstrates that this tool can be used for a large range of XUV fluences that are significantly lower than when probing by visible and near-infrared pulses. This tool is mainly targeted at emerging X-ray free-electron laser facilities, but can be utilized also at table-top high-harmonics sources. Full Article text
x Characterization of the soft X-ray spectrometer PEAXIS at BESSY II By scripts.iucr.org Published On :: 2020-01-01 The performance of the recently commissioned spectrometer PEAXIS for resonant inelastic soft X-ray scattering (RIXS) and X-ray photoelectron spectroscopy and its hosting beamline U41-PEAXIS at the BESSY II synchrotron are characterized. The beamline provides linearly polarized light from 180 eV to 1600 eV allowing for RIXS measurements in the range 200–1200 eV. The monochromator optics can be operated in different configurations to provide either high flux with up to 1012 photons s−1 within the focal spot at the sample or high energy resolution with a full width at half maximum of <40 meV at an incident photon energy of ∼400 eV. The measured total energy resolution of the RIXS spectrometer is in very good agreement with theoretically predicted values obtained by ray-tracing simulations. PEAXIS features a 5 m-long RIXS spectrometer arm that can be continuously rotated about the sample position by 106° within the horizontal photon scattering plane, thus enabling the study of momentum-transfer-dependent excitations. Selected scientific examples are presented to demonstrate the instrument capabilities, including measurements of excitations in single-crystalline NiO and in liquid acetone employing a fluid cell sample manipulator. Planned upgrades of the beamline and the RIXS spectrometer to further increase the energy resolution to ∼100 meV at 1000 eV incident photon energy are discussed. Full Article text
x Methods for dynamic synchrotron X-ray respiratory imaging in live animals By scripts.iucr.org Published On :: 2020-01-01 Small-animal physiology studies are typically complicated, but the level of complexity is greatly increased when performing live-animal X-ray imaging studies at synchrotron and compact light sources. This group has extensive experience in these types of studies at the SPring-8 and Australian synchrotrons, as well as the Munich Compact Light Source. These experimental settings produce unique challenges. Experiments are always performed in an isolated radiation enclosure not specifically designed for live-animal imaging. This requires equipment adapted to physiological monitoring and test-substance delivery, as well as shuttering to reduce the radiation dose. Experiment designs must also take into account the fixed location, size and orientation of the X-ray beam. This article describes the techniques developed to overcome the challenges involved in respiratory X-ray imaging of live animals at synchrotrons, now enabling increasingly sophisticated imaging protocols. Full Article text
x Full-field spectroscopic measurement of the X-ray beam from a multilayer monochromator using a hyperspectral X-ray camera By scripts.iucr.org Published On :: 2020-01-01 Multilayer monochromator devices are commonly used at (imaging) beamlines of synchrotron facilities to shape the X-ray beam to relatively small bandwidth and high intensity. However, stripe artefacts are often observed and can deteriorate the image quality. Although the intensity distribution of these artefacts has been described in the literature, their spectral distribution is currently unknown. To assess the spatio-spectral properties of the monochromated X-ray beam, the direct beam has been measured for the first time using a hyperspectral X-ray detector. The results show a large number of spectral features with different spatial distributions for a [Ru, B4C] strip monochromator, associated primarily with the higher-order harmonics of the undulator and monochromator. It is found that their relative contributions are sufficiently low to avoid an influence on the imaging data. The [V, B4C] strip suppresses these high-order harmonics even more than the former, yet at the cost of reduced efficiency. Full Article text
x White beam diagnostics using X-ray back-scattering from a CVD diamond vacuum window By scripts.iucr.org Published On :: 2020-01-01 Collecting back-scattered X-rays from vacuum windows using a pinhole X-ray camera provides an efficient and reliable method of measuring the beam shape and position of the white synchrotron beam. In this paper, measurements are presented that were conducted at ESRF beamline ID6 which uses an in-vacuum cryogenically cooled permanent-magnet undulator (CPMU18) and a traditional U32 undulator as its radiation sources, allowing tests to be performed at very high power density levels that were adjusted by changing the gap of the undulators. These measurements show that it is possible to record beam shape and beam position using a simple geometry without having to place any further items in the beam path. With this simple test setup it was possible to record the beam position with a root-mean-square noise figure of 150 nm. Full Article text
x Picosecond pump–probe X-ray scattering at the Elettra SAXS beamline By scripts.iucr.org Published On :: 2020-01-01 A new setup for picosecond pump–probe X-ray scattering at the Austrian SAXS beamline at Elettra-Sincrotrone Trieste is presented. A high-power/high-repetion-rate laser has been installed on-site, delivering UV/VIS/IR femtosecond-pulses in-sync with the storage ring. Data acquisition is achieved by gating a multi-panel detector, capable of discriminating the single X-ray pulse in the dark-gap of the Elettra hybrid filling mode. Specific aspects of laser- and detection-synchronization, on-line beam steering as well protocols for spatial and temporal overlap of laser and X-ray beam are also described. The capabilities of the setup are demonstrated by studying transient heat-transfer in an In/Al/GaAs superlattice structure and results are confirmed by theoretical calculations. Full Article text
x A semi-analytical approach for the characterization of ordered 3D nanostructures using grazing-incidence X-ray fluorescence By scripts.iucr.org Published On :: 2020-02-11 Following the recent demonstration of grazing-incidence X-ray fluorescence (GIXRF)-based characterization of the 3D atomic distribution of different elements and dimensional parameters of periodic nanoscale structures, this work presents a new computational scheme for the simulation of the angular-dependent fluorescence intensities from such periodic 2D and 3D nanoscale structures. The computational scheme is based on the dynamical diffraction theory in many-beam approximation, which allows a semi-analytical solution to the Sherman equation to be derived in a linear-algebraic form. The computational scheme has been used to analyze recently published GIXRF data measured on 2D Si3N4 lamellar gratings, as well as on periodically structured 3D Cr nanopillars. Both the dimensional and structural parameters of these nanostructures have been reconstructed by fitting numerical simulations to the experimental GIXRF data. Obtained results show good agreement with nominal parameters used in the manufacturing of the structures, as well as with reconstructed parameters based on the previously published finite-element-method simulations, in the case of the Si3N4 grating. Full Article text
x X-ray fluorescence detection for serial macromolecular crystallography using a JUNGFRAU pixel detector By scripts.iucr.org Published On :: 2020-02-07 Detection of heavy elements, such as metals, in macromolecular crystallography (MX) samples by X-ray fluorescence is a function traditionally covered at synchrotron MX beamlines by silicon drift detectors, which cannot be used at X-ray free-electron lasers because of the very short duration of the X-ray pulses. Here it is shown that the hybrid pixel charge-integrating detector JUNGFRAU can fulfill this function when operating in a low-flux regime. The feasibility of precise position determination of micrometre-sized metal marks is also demonstrated, to be used as fiducials for offline prelocation in serial crystallography experiments, based on the specific fluorescence signal measured with JUNGFRAU, both at the synchrotron and at SwissFEL. Finally, the measurement of elemental absorption edges at a synchrotron beamline using JUNGFRAU is also demonstrated. Full Article text
x AP-XPS beamline, a platform for operando science at Pohang Accelerator Laboratory By scripts.iucr.org Published On :: 2020-01-28 Beamline 8A (BL 8A) is an undulator-based soft X-ray beamline at Pohang Accelerator Laboratory. This beamline is aimed at high-resolution ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), soft X-ray absorption spectroscopy (soft-XAS) and scanning photoemission microscopy (SPEM) experiments. BL 8A has two branches, 8A1 SPEM and 8A2 AP-XPS, that share a plane undulator, the first mirror (M1) and the monochromator. The photon beam is switched between the two branches by changing the refocusing mirrors after the monochromator. The acceptance angle of M1 is kept glancing at 1.2°, and Pt is coated onto the mirrors to achieve high reflectance, which ensures a wide photon energy range (100–2000 eV) with high resolution at a photon flux of ∼1013 photons s−1. In this article, the main properties and performance of the beamline are reported, together with selected experiments performed on the new beamline and experimental system. Full Article text
x The HXD95: a modified Bassett-type hydrothermal diamond-anvil cell for in situ XRD experiments up to 5 GPa and 1300 K By scripts.iucr.org Published On :: 2020-01-29 A new diamond-anvil cell apparatus for in situ synchrotron X-ray diffraction measurements of liquids and glasses, at pressures from ambient to 5 GPa and temperatures from ambient to 1300 K, is reported. This portable setup enables in situ monitoring of the melting of complex compounds and the determination of the structure and properties of melts under moderately high pressure and high temperature conditions relevant to industrial processes and magmatic processes in the Earth's crust and shallow mantle. The device was constructed according to a modified Bassett-type hydrothermal diamond-anvil cell design with a large angular opening (θ = 95°). This paper reports the successful application of this device to record in situ synchrotron X-ray diffraction of liquid Ga and synthetic PbSiO3 glass to 1100 K and 3 GPa. Full Article text
x A five-axis parallel kinematic mirror unit for soft X-ray beamlines at MAX IV By scripts.iucr.org Published On :: 2020-01-29 With the introduction of the multi-bend achromats in the new fourth-generation storage rings the emittance has decreased by an order of magnitude resulting in increased brightness. However, the higher brightness comes with smaller beam sizes and narrower radiation cones. As a consequence, the requirements on mechanical stability regarding the beamline components increases. Here an innovative five-axis parallel kinematic mirror unit for use with soft X-ray beamlines using off-axis grazing-incidence optics is presented. Using simulations and measurements from the HIPPIE beamline at the MAX IV Laboratory it is shown that it has no Eigen frequencies below 90 Hz. Its positioning accuracy is better than 25 nm linearly and 17–35 µrad angularly depending on the mirror chamber dimensions. Full Article text
x A portable on-axis laser-heating system for near-90° X-ray spectroscopy: application to ferropericlase and iron silicide By scripts.iucr.org Published On :: 2020-02-13 A portable IR fiber laser-heating system, optimized for X-ray emission spectroscopy (XES) and nuclear inelastic scattering (NIS) spectroscopy with signal collection through the radial opening of diamond anvil cells near 90°with respect to the incident X-ray beam, is presented. The system offers double-sided on-axis heating by a single laser source and zero attenuation of incoming X-rays other than by the high-pressure environment. A description of the system, which has been tested for pressures above 100 GPa and temperatures up to 3000 K, is given. The XES spectra of laser-heated Mg0.67Fe0.33O demonstrate the potential to map the iron spin state in the pressure–temperature range of the Earth's lower mantle, and the NIS spectra of laser-heated FeSi give access to the sound velocity of this candidate of a phase inside the Earth's core. This portable system represents one of the few bridges across the gap between laser heating and high-resolution X-ray spectroscopies with signal collection near 90°. Full Article text
x ProQEXAFS: a highly optimized parallelized rapid processing software for QEXAFS data By scripts.iucr.org Published On :: 2020-02-07 The high temporal resolution in data acquisition, possible in the quick-scanning EXAFS (QEXAFS) mode of operation, provides new challenges in efficient data processing methods. Here a new approach is developed that combines an easy to use interactive graphical interface with highly optimized and fully parallelized Python-based routines for extracting, normalizing and interpolating oversampled time-resolved XAS spectra from a raw binary stream of data acquired during operando QEXAFS studies. The programs developed are freely available via a Github repository. Full Article text
x X-ray free-electron laser wavefront sensing using the fractional Talbot effect By scripts.iucr.org Published On :: 2020-02-12 Wavefront sensing at X-ray free-electron lasers is important for quantitatively understanding the fundamental properties of the laser, for aligning X-ray instruments and for conducting scientific experimental analysis. A fractional Talbot wavefront sensor has been developed. This wavefront sensor enables measurements over a wide range of energies, as is common on X-ray instruments, with simplified mechanical requirements and is compatible with the high average power pulses expected in upcoming X-ray free-electron laser upgrades. Single-shot measurements were performed at 500 eV, 1000 eV and 1500 eV at the Linac Coherent Light Source. These measurements were applied to study both mirror alignment and the effects of undulator tapering schemes on source properties. The beamline focal plane position was tracked to an uncertainty of 0.12 mm, and the source location for various undulator tapering schemes to an uncertainty of 1 m, demonstrating excellent sensitivity. These findings pave the way to use the fractional Talbot wavefront sensor as a routine, robust and sensitive tool at X-ray free-electron lasers as well as other high-brightness X-ray sources. Full Article text
x IRIXS: a resonant inelastic X-ray scattering instrument dedicated to X-rays in the intermediate energy range By scripts.iucr.org Published On :: 2020-02-26 A new resonant inelastic X-ray scattering (RIXS) instrument has been constructed at beamline P01 of the PETRA III synchrotron. This instrument has been named IRIXS (intermediate X-ray energy RIXS) and is dedicated to X-rays in the tender-energy regime (2.5–3.5 keV). The range covers the L2,3 absorption edges of many of the 4d elements (Mo, Tc, Ru, Rh, Pd and Ag), offering a unique opportunity to study their low-energy magnetic and charge excitations. The IRIXS instrument is currently operating at the Ru L3-edge (2840 eV) but can be extended to the other 4d elements using the existing concept. The incoming photons are monochromated with a four-bounce Si(111) monochromator, while the energy analysis of the outgoing photons is performed by a diced spherical crystal analyzer featuring (102) lattice planes of quartz (SiO2). A total resolution of 100 meV (full width at half-maximum) has been achieved at the Ru L3-edge, a number that is in excellent agreement with ray-tracing simulations. Full Article text