A curved image‐plate detector system for high‐resolution synchrotron X‐ray diffraction

The developed curved image plate (CIP) is a one‐dimensional detector which simultaneously records high‐resolution X‐ray diffraction (XRD) patterns over a 38.7° 2θ range. In addition, an on‐site reader enables rapid extraction, transfer and storage of X‐ray intensity information in ≤30 s, and further qualifies this detector to study kinetic processes in materials science. The CIP detector can detect and store X‐ray intensity information linearly proportional to the incident photon flux over a dynamical range of about five orders of magnitude. The linearity and uniformity of the CIP detector response is not compromised in the unsaturated regions of the image plate, regardless of saturation in another region. The speed of XRD data acquisition together with excellent resolution afforded by the CIP detector is unique and opens up wide possibilities in materials research accessible through X‐ray diffraction. This article presents details of the basic features, operation and performance of the CIP detector along with some examples of applications, including high‐temperature XRD.     

On‐line optical and X‐ray spectroscopies with crystallography: an integrated approach for determining metalloprotein structures in functionally well defined states

X‐ray‐induced redox changes can lead to incorrect assignments of the functional states of metals in metalloprotein crystals. The need for on‐line monitoring of the status of metal ions (and other chromophores) during protein crystallography experiments is of growing importance with the use of intense synchrotron X‐ray beams. Significant efforts are therefore being made worldwide to combine different spectroscopies in parallel with X‐ray crystallographic data collection. Here the implementation and utilization of optical and X‐ray absorption spectroscopies on the modern macromolecular crystallography (MX) beamline 10, at the SRS, Daresbury Laboratory, is described. This beamline is equipped with a dedicated monolithic energy‐dispersive X‐ray fluorescence detector, allowing X‐ray absorption spectroscopy (XAS) measurements to be made in situ on the same crystal used to record the diffraction data. In addition, an optical microspectrophotometer has been incorporated on the beamline, thus facilitating combined MX, XAS and optical spectroscopic measurements. By uniting these techniques it is also possible to monitor the status of optically active and optically silent metal centres present in a crystal at the same time. This unique capability has been applied to observe the results of crystallographic data collection on crystals of nitrite reductase from Alcaligenes xylosoxidans, which contains both type‐1 and type‐2 Cu centres. It is found that the type‐1 Cu centre photoreduces quickly, resulting in the loss of the 595 nm peak in the optical spectrum, while the type‐2 Cu centre remains in the oxidized state over a much longer time period, for which independent confirmation is provided by XAS data as this centre has an optical spectrum which is barely detectable using microspectrophotometry. This example clearly demonstrates the importance of using two on‐line methods, spectroscopy and XAS, for identifying well defined redox states of metalloproteins during crystallographic data collection.     

XDS: a flexible beamline for X‐ray diffraction and spectroscopy at the Brazilian synchrotron

The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage‐ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X‐ray spectrum (above ～10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi‐purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X‐ray absorption spectroscopy at energies above 18 keV and high‐resolution diffraction experiments. More recently, new setups and photon‐hungry experiments such as total X‐ray scattering, X‐ray diffraction under high pressures, resonant X‐ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.     

The multi‐purpose hard X‐ray beamline BL10 at the DELTA storage ring

The layout and the characteristics of the hard X‐ray beamline BL10 at the superconducting asymmetric wiggler at the 1.5 GeV Dortmund Electron Accelerator DELTA are described. This beamline is equipped with a Si(111) channel‐cut monochromator and is dedicated to X‐ray studies in the spectral range from ～4 keV to ～16 keV photon energy. There are two different endstations available. While X‐ray absorption studies in different detection modes (transmission, fluorescence, reflectivity) can be performed on a designated table, a six‐axis kappa diffractometer is installed for X‐ray scattering and reflectivity experiments. Different detector set‐ups are integrated into the beamline control software, i.e. gas‐filled ionization chambers, different photodiodes, as well as a Pilatus 2D‐detector are permanently available. The performance of the beamline is illustrated by high‐quality X‐ray absorption spectra from several reference compounds. First applications include temperature‐dependent EXAFS experiments from liquid‐nitrogen temperature in a bath cryostat up to ～660 K by using a dedicated furnace. Besides transmission measurements, fluorescence detection for dilute sample systems as well as surface‐sensitive reflection‐mode experiments are presented.     

Soft X‐ray absorption spectroscopy and resonant inelastic X‐ray scattering spectroscopy below 100 eV: probing first‐row transition‐metal M‐edges in chemical complexes

X‐ray absorption and scattering spectroscopies involving the 3d transition‐metal K‐ and L‐edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M‐edges, which are below 100 eV. Synchrotron‐based X‐ray sources can have higher energy resolution at M‐edges. M‐edge X‐ray absorption spectroscopy (XAS) and resonant inelastic X‐ray scattering (RIXS) could therefore provide complementary information to K‐ and L‐edge spectroscopies. In this study, M_2,3‐edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M_2,3‐edge RIXS on NiO, NiF₂ and two other covalent complexes have been performed and different d–d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M‐edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high‐sensitivity and high‐resolution superconducting tunnel junction X‐ray detectors below 100 eV is also illustrated and discussed.     

High‐performance X‐ray detectors for the new powder diffraction beamline I11 at Diamond

The design and performance characterization of a new light‐weight and compact X‐ray scintillation detector is presented. The detectors are intended for use on the new I11 powder diffraction beamline at the third‐generation Diamond synchrotron facility where X‐ray beams of high photon brightness are generated by insertion devices. The performance characteristics of these detection units were measured first using a radioactive source (efficiency of detection and background count rate) and then synchrotron X‐rays (peak stability, light yield linearity and response consistency). Here, the results obtained from these tests are reported, and the suitability of the design for the Diamond powder beamline is demonstrated by presenting diffraction data obtained from a silicon powder standard using a prototype multicrystal analyser stage.     

Performance of a fuel cell optimized for in situ X‐ray absorption experiments

A commercial fuel cell has been successfully modified to carry out X‐ray absorption spectroscopy (XAS) measurements under optimized in operando conditions. The design is conceived for the performance of XAS experiments in transmission mode over a wide range of X‐ray energies above 6 keV, owing to the reduced absorption of the cell. The wide angular aperture allows the collection of XAS in fluorescence mode and of X‐ray diffraction patterns when needed. Details of the design of the cell and its performances are given. The quality of the extended X‐ray absorption fine‐structure spectra under working conditions has been verified at the ESRF and ELETTRA synchrotron radiation facilities, showing that relatively fast and low‐noise transmission measurements on electrodes over a wide range of catalyst concentrations and energies are feasible.     

Pressure study of monoclinic ReO2 up to 1.2 GPa using X‐ray absorption spectroscopy and X‐ray diffraction

The crystal and local atomic structure of monoclinic ReO₂ (α‐ReO₂) under hydrostatic pressure up to 1.2 GPa was investigated for the first time using both X‐ray absorption spectroscopy and high‐resolution synchrotron X‐ray powder diffraction and a home‐built B₄C anvil pressure cell developed for this purpose. Extended X‐ray absorption fine‐structure (EXAFS) data analysis at pressures from ambient up to 1.2 GPa indicates that there are two distinct Re—Re distances and a distorted ReO₆ octahedron in the α‐ReO₂ structure. X‐ray diffraction analysis at ambient pressure revealed an unambiguous solution for the crystal structure of the α‐phase, demonstrating a modulation of the Re—Re distances. The relatively small portion of the diffraction pattern accessed in the pressure‐dependent measurements does not allow for a detailed study of the crystal structure of α‐ReO₂ under pressure. Nonetheless, a shift and reduction in the (011) Bragg peak intensity between 0.4 and 1.2 GPa is observed, with correlation to a decrease in Re—Re distance modulation, as confirmed by EXAFS analysis in the same pressure range. This behavior reveals that α‐ReO₂ is a possible inner pressure gauge for future experiments up to 1.2 GPa.     

A miniature X‐ray emission spectrometer (miniXES) for high‐pressure studies in a diamond anvil cell

Core–shell X‐ray emission spectroscopy (XES) is a valuable complement to X‐ray absorption spectroscopy (XAS) techniques. However, XES in the hard X‐ray regime is much less frequently employed than XAS, often as a consequence of the relative scarcity of XES instrumentation having energy resolutions comparable with the relevant core‐hole lifetimes. To address this, a family of inexpensive and easily operated short‐working‐distance X‐ray emission spectrometers has been developed. The use of computer‐aided design and rapid prototype machining of plastics allows customization for various emission lines having energies from ～3 keV to ～10 keV. The specific instrument described here, based on a coarsely diced approximant of the Johansson optic, is intended to study volume collapse in Pr metal and compounds by observing the pressure dependence of the Pr Lα emission spectrum. The collection solid angle is ～50 msr, roughly equivalent to that of six traditional spherically bent crystal analyzers. The miniature X‐ray emission spectrometer (miniXES) methodology will help encourage the adoption and broad application of high‐resolution XES capabilities at hard X‐ray synchrotron facilities.     

The small‐angle and wide‐angle X‐ray scattering set‐up at beamline BL9 of DELTA

The multi‐purpose experimental endstation of beamline BL9 at the Dortmund Electron Accelerator (DELTA) is dedicated to diffraction experiments in grazing‐incidence geometry, reflectivity and powder diffraction measurements. Moreover, fluorescence analysis and inelastic X‐ray scattering experiments can be performed. Recently, a new set‐up for small‐angle and wide‐angle X‐ray scattering utilizing detection by means of an image‐plate scanner was installed and is described in detail here. First small‐angle X‐ray scattering experiments on aqueous solutions of lysozyme with different cosolvents and of staphylococcal nuclease are discussed. The application of the set‐up for texture analysis is emphasized and a study of the crystallographic texture of natural bio‐nanocomposites, using lobster and crab cuticles as model materials, is presented.     

IDATEN and G‐SITENNO: GUI‐assisted software for coherent X‐ray diffraction imaging experiments and data analyses at SACLA

Using our custom‐made diffraction apparatus KOTOBUKI‐1 and two multiport CCD detectors, cryogenic coherent X‐ray diffraction imaging experiments have been undertaken at the SPring‐8 Angstrom Compact free electron LAser (SACLA) facility. To efficiently perform experiments and data processing, two software suites with user‐friendly graphical user interfaces have been developed. The first is a program suite named IDATEN, which was developed to easily conduct four procedures during experiments: aligning KOTOBUKI‐1, loading a flash‐cooled sample into the cryogenic goniometer stage inside the vacuum chamber of KOTOBUKI‐1, adjusting the sample position with respect to the X‐ray beam using a pair of telescopes, and collecting diffraction data by raster scanning the sample with X‐ray pulses. Named G‐SITENNO, the other suite is an automated version of the original SITENNO suite, which was designed for processing diffraction data. These user‐friendly software suites are now indispensable for collecting a large number of diffraction patterns and for processing the diffraction patterns immediately after collecting data within a limited beam time.     

Status of the hard X‐ray microprobe beamline ID22 of the European Synchrotron Radiation Facility

The ESRF synchrotron beamline ID22, dedicated to hard X‐ray microanalysis and consisting of the combination of X‐ray fluorescence, X‐ray absorption spectroscopy, diffraction and 2D/3D X‐ray imaging techniques, is one of the most versatile instruments in hard X‐ray microscopy science. This paper describes the present beamline characteristics, recent technical developments, as well as a few scientific examples from recent years of the beamline operation. The upgrade plans to adapt the beamline to the growing needs of the user community are briefly discussed.     

Fabrication and testing of a newly designed slit system for depth‐resolved X‐ray diffraction measurements

A new system of slits called `spiderweb slits' have been developed for depth‐resolved powder or polycrystalline X‐ray diffraction measurements. The slits act on diffracted X‐rays to select a particular gauge volume of sample, while absorbing diffracted X‐rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of diffraction angles, and work for X‐ray energies of tens to hundreds of kiloelectronvolts. The design is generated and optimized using ray‐tracing simulations, and fabricated through laser micromachining. The first prototype was successfully tested at the X17A beamline at the National Synchrotron Light Source, and shows similar performance to simulations, demonstrating gauge volume selection for standard powders, for all diffraction peaks over angles of 2–10°. A similar, but improved, design will be implemented at the X‐ray Powder Diffraction beamline at the National Synchrotron Light Source II.     

Performance of the micro‐PIC gaseous area detector in small‐angle X‐ray scattering experiments

The application of a two‐dimensional photon‐counting detector based on a micro‐pixel gas chamber (µ‐PIC) to high‐resolution small‐angle X‐ray scattering (SAXS), and its performance, are reported. The µ‐PIC is a micro‐pattern gaseous detector fabricated by printed circuit board technology. This article describes the performance of the µ‐PIC in SAXS experiments at SPring‐8. A dynamic range of >10⁵ was obtained for X‐ray scattering from a polystyrene sphere solution. A maximum counting rate of up to 5 MHz was observed with good linearity and without saturation. For a diffraction pattern of collagen, weak peaks were observed in the high‐angle region in one accumulation of photons.     

High‐resolution spectroscopy on an X‐ray absorption beamline

A bent‐crystal spectrometer based on the Rowland circle geometry has been installed and tested on the BM30b/FAME beamline at the European Synchrotron Radiation Facility to improve its performances. The energy resolution of the spectrometer allows different kinds of measurements to be performed, including X‐ray absorption spectroscopy, resonant inelastic X‐ray scattering and X‐ray Raman scattering experiments. The simplicity of the experimental device makes it easily implemented on a classical X‐ray absorption beamline. This improvement in the fluorescence detection is of particular importance when the probed element is embedded in a complex and/or heavy matrix, for example in environmental sciences.     

Coherent X‐ray scattering beamline at port 9C of Pohang Light Source II

The coherent X‐ray scattering beamline at the 9C port of the upgraded Pohang Light Source (PLS‐II) at Pohang Accelerator Laboratory in Korea is introduced. This beamline provides X‐rays of 5–20 keV, and targets coherent X‐ray experiments such as coherent diffraction imaging and X‐ray photon correlation spectroscopy. The main parameters of the beamline are summarized, and some preliminary experimental results are described.     

A Geiger‐mode avalanche photodiode array for X‐ray photon correlation spectroscopy

X‐ray photon correlation spectroscopy (XPCS) provides an opportunity to study the dynamics of systems by measuring the temporal fluctuations in a far‐field diffraction pattern. A two‐dimensional detector system has been developed to investigate fluctuations in the frequency range of several Hz to kHz. The X‐ray detector system consists of a thin 100 µm scintillation crystal coupled to a Geiger‐mode avalanche photodiode array. In this article the elements of the system are detailed and the detector for XPCS measurements is demonstrated.     

A three‐crystal spectrometer for high‐energy resolution fluorescence‐detected X‐ray absorption spectroscopy and X‐ray emission spectroscopy at SSRF

A Johann‐type spectrometer for the study of high‐energy resolution fluorescence‐detected X‐ray absorption spectroscopy, X‐ray emission spectroscopy and resonant inelastic X‐ray scattering has been developed at BL14W1 X‐ray absorption fine structure spectroscopy beamline of Shanghai Synchrotron Radiation Facility. The spectrometer consists of three crystal analyzers mounted on a vertical motion stage. The instrument is scanned vertically and covers the Bragg angle range of 71.5–88°. The energy resolution of the spectrometer ranges from sub‐eV to a few eV. The spectrometer has a solid angle of about 1.87 × 0^?3 of 4π sr, and the overall photons acquired by the detector could be 10⁵ counts per second for the standard sample. The performances of the spectrometer are illustrated by the three experiments that are difficult to perform with the conventional absorption or emission spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterization of pottery from Republic of Macedonia. III. A study of comparative mineralogical detection efficiency using micro‐Raman mapping and X‐ray diffraction

Point‐to‐point micro‐Raman and X‐ray diffraction (XRD) techniques were employed for characterization of minerals present in the pottery body of 27 glazed Byzantine and Ottoman pottery shreds, excavated at two different archaeological sites in the Republic of Macedonia: in Skopje (Skopsko Kale) and in Prilep (Markovi Kuli and Sv. Atanas Church). The Raman spectra of 18 Byzantine samples (dating from 12th−14th century) and nine Ottoman samples (dating from 17th−19th century) revealed 26 different minerals. XRD measurements were further performed on the same powder samples to validate the mineralogical assessment obtained by point‐to‐point micro‐Raman spectroscopy. Although only 13 different mineral phases were obtained by the XRD, the results obtained from the Raman and XRD spectra for the most abundant minerals in the investigated pottery bodies match quite well. However, the identification of the less abundant minerals in the clay matrixes from the XRD data was very difficult, if at all possible. The results emphasize the specifics of the applied techniques and their limits. Additionally, wavelength dispersive X‐ray fluorescence spectroscopy was used for the elemental analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

Continuous‐scan capability at SSRL and applications to X‐ray diffraction

Typical X‐ray diffraction measurements are made by moving a detector to discrete positions in space and then measuring the signal at each stationary position. This step‐scanning method can be time‐consuming, and may induce vibrations in the measurement system when the motors are accelerated and decelerated at each position. Furthermore, diffraction information between the data points may be missed unless a fine step‐scanning is used, which further increases the total measurement time. To utilize beam time efficiently, the motor acceleration and deceleration time should be minimized, and the signal‐to‐noise ratio should be maximized. To accomplish this, an integrated continuous‐scan system was developed at the Stanford Synchrotron Radiation Lightsource (SSRL). The continuous‐scan system uses an in‐house integrated motor controller system and counter/timer electronics. SPEC software is used to control both the hardware and data acquisition systems. The time efficiency and repeatability of the continuous‐scan system were tested using X‐ray diffraction from a ZnO powder and compared with the step‐scan technique. Advantages and limitations of the continuous‐scan system and a demonstration of variable‐velocity continuous scan are discussed.