Journal of Synchrotron Radiation最新文献

A three-dimensional analysis method for X-ray absorption spectra, combining two-metal-edge extended X-ray absorption fine structure (EXAFS) analysis with reverse Monte Carlo simulations, was applied to study the cubic-to-tetragonal phase transition in SrTiO₃ as a dielectric standard. This method allows for the evaluation of both the static distribution and the dynamic motion of atoms, including oxygen. The optimized clusters reveal that the TiO₆ octahedron can rotate up to 2.7° below the phase transition temperature, driven by reduced A-site Sr dynamics. Within the framework of conventional EXAFS analysis, the high-precision determination of atomic positions using the two-metal-edge analysis for ternary materials enhances the detection of light elements, and the method is applicable to bimetallic oxides and nitrides.

With the rapid development of X-ray free-electron lasers (XFELs) that can generate ultrashort X-ray pulses with a duration range from attoseconds to femtoseconds, the study of ultrashort XFEL pulse propagation in beamline systems is increasingly important, especially in dispersive beamline systems. We developed a 6D phase space ray-tracing method to simulate pulse propagation in dispersive soft X-ray optical systems. We validated this method by simulating a typical dispersive optical system: a grating monochromator. The simulation indicated that the spatiotemporal properties such as pulse front tilt, pulse front rotation and angular dispersion can be described. Using this approach, we performed a start-to-end simulation of the Shenzhen Superconducting Soft X-ray Free Electron Laser (S³FEL) FEL-1 beamline. Compared with the 3D pulse propagation method based on Fourier optics, this significantly reduces the simulation time. Our work provides a useful tool for X-ray beamline systems design.

Fastosh is a freeware dedicated to the treatment of X-ray absorption fine-structure (XAFS) spectroscopy data. The program features functions that are particularly suitable for geochemical and environmental applications and treatment of XAFS datasets acquired in operando conditions. It can be employed to identify the nature of chemical species present as principal components in a sample mixture, which is a case commonly encountered when studying a set of natural samples or a chemical reaction followed in situ at the beamline, where multiple species may coexist, including intermediary species. Additionally, the software features unique functionalities that notably allow to filter in two dimensions and plot in three dimensions time-dependent datasets; rapidly deglitch chi spectra; automatically view in 2D or 3D and merge XAFS data acquired at the beamline; and visualize an EXAFS wavelet transform map as well as interpret it and its associated chi and Fourier transform spectra using a quick modelling approach where theoretical single scattering paths are employed. All these functions can be applied to XAFS data generated in ASCII format at any XAFS beamlines. Lastly, the program specifically allows users of SAMBA beamline, Synchrotron SOLEIL, to easily access all contextual data associated with an XAFS acquisition or process the raw data collected by the multi-pixel fluorescence detector of the beamline, which are saved in an HDF file. The structure of this file, and all related functions in Fastosh to exploit it, could be readily adapted to comply with a universal HDF format, which hopefully will be defined and adopted in the future by multiple XAFS beamlines worldwide.

The structural biology program at the National Synchrotron Light Source II presents a coordinated set of instruments, software and research opportunities for the interested user. We describe in some detail the research capabilities enabled by the Center for BioMolecular Structure. The evolution of the resources is described in detail, considering three major themes: automation, micro-focusing and computation prediction.

A 1.6 m-long 16 mm-period superconducting undulator (SCU16) has been installed and commissioned at the Australian Synchrotron. The SCU16, developed by Bilfinger, is based on the SCU20 currently operating at Karlsruhe Institute of Technology (KIT). The SCU16 is conduction cooled with a maximum on-axis field of 1.084 T and a fixed effective vacuum gap of 5.5 mm. The design, commissioning experience and performance of one of the longest superconducting undulators at a light source are presented.

The name of an author in the article by Walter et al. (2022) [J. Synchrotron Rad. 29, 957-968] is corrected.

The superconducting wiggler beamline IMAGE at the KIT Light Source is dedicated to full-field hard X-ray imaging applications in materials and life sciences, with a focus on high-throughput computed tomography, laminography experiments and systematic in situ and operando studies. With two experimental hutches, IMAGE provides space for its dedicated permanent experimental stations UFO-II and LAMINO-II as well as for flexible custom setups. IMAGE allows parallel beam imaging experiments in monochromatic, pink or white beam mode, with spatial resolutions ranging from ∼1 µm to ∼30 µm and a large horizontal and vertical field of view of up to 44 mm × 8 mm, respectively. Photon energies between 8 keV and 40 keV are provided by a double-crystal or double-multilayer monochromator optics with energy resolutions of 0.01% and 1.5-2.7%, respectively. The filtered white beam mode provides high flux densities of up to 7.5 × 10¹⁴ photons s^-1 mm^-2 at the sample position and energy spectra extending up to about 120 keV.

We present a modular instrument for dispersive X-ray absorption spectroscopy (DXAS) developed for the Advanced Spectroscopy Beamline at Sector 25 of the Advanced Photon Source. The setup employs a double-multilayer monochromator to provide X-rays with a broad energy bandwidth, Kirkpatrick-Baez mirrors for focusing, a convexly bent Bragg-crystal polychromator for energy dispersion, and a pixel-array detector to resolve all X-ray energies and collect their intensity simultaneously, thereby enabling acquisition of a full X-ray absorption spectrum in a single shot. The use of separate optics for X-ray focusing and energy dispersion provides high spatial resolution and avoids chromatic aberrations inherent in focusing bent-crystal optics, and a modular design makes implementation of the technique at other beamlines possible without requiring modifications to the upstream beamline configurations. Theoretical calculations are performed to determine optimal instrument operating parameters and demonstrate that an energy resolution better than the K-edge core-hole lifetime broadening can be maintained while providing a sufficient bandwidth for X-ray absorption near-edge structure spectroscopy through the full operating range of 5-11 keV. Additionally, instrument design, data analysis methods, and initial DXAS results on lithium-manganese-nickel oxide laminates are presented.

An advanced imaging platform has been developed to study the microstructural solidification behaviors of metals using synchrotron white X-rays. This system provides submicrometre effective pixel size and a frame rate of thousands per second, enabling high-resolution and high-speed imaging. The system functions independently, facilitating convenient alignment, magnification adjustments, and precise control of the region of interest. Additionally, we designed a specialized furnace for in situ characterization of microstructures during melting and solidification of metallic specimens at high temperature. This furnace meets stringent optical requirements and allows for finely adjusted specimen temperature gradients through the configuration of heating elements and individual current control. The furnace supports stable high-temperature experiments under vacuum, in an argon atmosphere, and at ambient pressure. Using this advanced imaging system, we investigated real-time in situ solidification phenomena of various metallic materials and other solidifying systems such as silicon. We performed image analysis to quantitatively assess microstructural changes, calculate dendritic spacing and determine liquid fractions.

We report on the commissioning of an ultrafast timing diagnostic for measuring a time-offset signal between two different synchronized ultrashort light pulses. The method is based on sum-frequency generation in a nonlinear crystal. The setup is similar to an auto/cross-correlator setup. In this case, one of the beams is a relatively weak diagnostic beam of visible light from a bending magnet at FemtoMAX (10⁶ photons pulse^-1 in a 0.2 mm high and 5 mm wide beam) while the other is a relatively intense laser beam (200 µJ pulse^-1) derived from the same laser that is used to pump the sample in pump/probe experiments. This enables online monitoring of the relative timing of a linear accelerator-based, short-pulse, hard X-ray source and a synchronized visible laser. We show that for a <50 fs full width at half-maximum (FWHM) light pulse from the accelerator and a 50 fs (FWHM) long laser pulse, we can determine the relative timing of the two pulses with an accuracy below 30 fs in a time interval of 4 ps. The advantages and limitations of the method are discussed.