Journal of Synchrotron Radiation最新文献

The MUSTACHE setup (MUlti-STep photofragmentation studies by Auger electron-ion Coincidences using High Energy photons) is a high-resolution electron-multi-ion coincidence system optimized for gas-phase experiments in the tender (∼2-10 keV) and hard (>5 keV) X-ray range. The system integrates a high-resolution hemispherical electron analyzer with a Wiley-McLaren-type ion time-of-flight (TOF) spectrometer, enabling coincidence measurements of Auger electrons and high-energy photoelectrons. Designed to overcome challenges in high-energy electron detection while maintaining excellent energy resolution, the setup covers a broad kinetic energy range up to 5 keV, allowing investigation of hard-X-ray-induced Auger cascades in molecules containing high-Z elements, where initial fluorescence decay is followed by Auger processes within this 5 keV detection window. The ion TOF spectrometer provides high-resolution ion mass and momentum analysis, essential for studying light and fast ions generated by deep-core ionization. System capabilities are demonstrated through test measurements on benchmark atomic and molecular systems, such as argon, nitrogen and carbon disulfide. These measurements demonstrate energy-resolved high-kinetic-energy photoelectron-ion coincidences and momentum-resolved multi-ion coincidences following deep-core ionization and Coulomb explosion. MUSTACHE enables investigations into deep-core ionization, Auger cascade processes and Coulomb explosion dynamics in isolated gas-phase species, offering insights into fundamental ionization and fragmentation processes. These results demonstrate that the MUSTACHE setup is a powerful tool for high-resolution electron-ion coincidence spectroscopy, extending advanced coincidence techniques into the hard X-ray regime and providing unprecedented opportunities for studying high-energy X-ray-induced phenomena.

The continuous-wave free-electron laser (CW-FEL), based on superconducting radiofrequency (SRF) technology with an electron bunch repetition rate of up to MHz levels, is one of the most advanced light sources, providing exceptionally high average and peak-brightness FEL pulses. Among the new CW-FEL facilities worldwide, the recently proposed Dalian Advanced Light Source (DALS) occupies a unique position as an extreme ultraviolet (EUV) facility primarily designed for chemical physics research. Since the beam emittance requirement for DALS is not as stringent as that for X-ray CW-FEL facilities, a direct current (DC) gun is considered as the primary electron source, with a very high frequency (VHF) gun also planned. To demonstrate key technologies and characterize the electron beam performance, a superconducting CW injector testbed, named the Electron Source Test Facility (ESTF), has been designed and is currently under construction. The testbed is uniquely designed to accommodate both guns with minimal switching effort, where the rest of the beamline layout remains unchanged except for the swapped guns. The two-gun switching scheme for the testbed is shown to be a feasible and cost-effective approach. Furthermore, the injector performance with both guns has been evaluated through a start-to-end simulation based on the DALS configuration, including the production of electron beam in the ESTF injector, the following beam acceleration and compression in a superconducting linear accelerator, and finally the beam lasing performance in the undulator section. The evaluation confirms that the DC gun is a promising electron source for CW-FEL facilities, especially for EUV applications, even though all currently constructed CW facilities have employed the VHF gun. This paper provides a comprehensive description of the injector design and the corresponding performance evaluation.

Single-particle imaging at X-ray free-electron lasers relies on suitable sample injection of nanoscale macromolecules and particles into the gas phase at room temperature. A coaxial liquid-sheet strategy considerably extended the range of suitable samples to include conductivities from zero to 40000 µS cm^-1 - a more than about an eightfold increase in range compared with conventional electrosprays. A helium chamber atmosphere in combination with an engineered gas-sheet protected aerosol formation against corona discharge and reduced background noise more than threefold. These results suggest new avenues to qualify ever more demanding biological and material science samples for single-particle imaging in the future.

Magnetic vector tomography allows for visualizing the 3D magnetization vector of magnetic nanostructures and multilayers with nanometric resolution. In this work, we present MARTApp (Magnetic Analysis and Reconstruction of Tomographies Application), a software designed to analyze the images obtained from a full-field or scanning transmission X-ray microscope and reconstruct the 3D magnetization of the sample. Here, its workflow and main features are described. Moreover, a synthetic test sample consisting of a hopfion is used to exemplify the workflow from raw images to the final 3D magnetization reconstruction.

Existing beamlines for in situ grazing-incidence small-angle scattering on liquids are either limited in angular range or incompatible with the large sample-detector distance required for submicrometre resolution. We present a low-cost, easily assembled beam-tilting extension for synchrotron-based ultra-small-angle X-ray scattering (USAXS) facilities, enabling grazing-incidence and transmitted scattering (GIUSAXS, GTUSAXS) studies on liquid surfaces. The setup is compatible with standard USAXS beamlines and requires only ∼0.5 m of additional space at the sample stage. It allows X-ray beam incidence angles of up to ∼0.6° at the liquid surface, equal to twice the angle of incidence on a reflector and below its critical angle of typical materials (e.g. silicon, germanium, etc.), and provides access to a q-range of approximately 0.003-0.5 nm^-1. The system was tested at P03 beamline (DESY) using polystyrene nanoparticles (∼197 nm) self-assembled at the air/water interface. The recorded GIUSAXS and GTSAXS patterns revealed features characteristic of near-surface hexagonally ordered monolayers and multilayer assemblies, validating the system's resolution and sensitivity. The proposed scheme enables selective depth profiling and expands the research capabilities of existing small-angle X-ray scattering synchrotron facilities for in situ studyies of submicrometre nanostructured objects at liquid surfaces under grazing-incidence geometry, while remaining fully compatible with complementary techniques such as grazing-incidence wide-angle scattering and total reflection X-ray fluorescence.

Many of the 70 synchrotron facilities worldwide are undergoing upgrades to their infrastructure to meet a growing demand for increased beam brightness with nanometre-level stability. These upgrades increase the mechanical and thermal challenges faced by beamline components, creating opportunities to apply novel methodologies and manufacturing processes to optimize hardware performance and beam accuracy. Absorbers are important beamline components that rely on water-cooled channels to absorb thermal energy from excess light caused by synchrotron radiation or photon beams created by insertion devices, all within a limited volume, to protect downstream equipment and ensure safe, reliable operation. Additive manufacturing (AM) has been shown to meet criteria relevant to synchrotron environments like leak tightness and vacuum compatibility. However, there is a research gap on the heat transfer and pressure drop impact of different AM conformal cooling channel geometries, as well as the print quality of AM copper parts using low-power infrared lasers and their compliance with absorber requirements. In this study, an intermediate model of a Diamond Light Source photon absorber was optimized to incorporate AM conformal cooling channels, leading to two concept designs named `Horizontal' and `Coil'. When compared with the baseline design, the lightweight Horizontal concept performed the best in this study, with simulations showing a maximum temperature drop of 11%, a calculated pressure drop reduction of 82%, a mass reduction of 86%, and the consolidation of 21 individually brazed pipes into a single manifold. The AM print quality and compliance with the synchrotron environment was examined by producing custom benchmark artefacts and measuring their surface roughness, dimensional accuracy and porosity levels, which are characteristics that can affect heat absorption, structural integrity, thermal conductivity and vacuum performance. The study demonstrates the benefits and addresses outstanding challenges in reducing thermal fatigue, as well as the size, vibrations and energy consumption of AM absorbers.

For several years, photon-counting X-ray imaging detectors with cadmium telluride (CdTe) sensors have been used in high-energy synchrotron experiments. While these detectors exhibit excellent detection sensitivity at high energy, concerns remain regarding their performance stability over time under exposure to high-energy X-rays, an issue that can be critical for certain experiments. This study aims to quantitatively assess the response of ohmic-type CdTe sensors under well defined conditions of continuous X-ray irradiation, considering dose rate, photon energy and average absorbed dose throughout the sensor depth. Measurements were performed in a laboratory environment using a dedicated setup with a reliable and reproducible measurement protocol. The results revealed significant irradiation-induced performance variations over time. Notably, a loss of more than 11% in photon counts was observed, even at a relatively low photon flux of 5000 photons s^-1 pixel^-1 at 49 keV. The key contribution of this work is a quantitative characterization of the behavior of CdTe sensors within the 12-49 keV energy range under controlled conditions. These findings provide essential insights for synchrotron experiments operating in this energy range. Furthermore, the proposed measurement protocol offers a reliable method for quantitatively comparing the stability of other high-Z sensor materials against state-of-the-art CdTe technology.

Vanadium in basic-oxygen-furnace (BOF) slags is particularly interesting regarding the recovery of this element, which has been further strengthened by its inclusion in the list of critical raw materials by the European Union in 2017. As BOF slags can have a significant vanadium content, they continue to be a promising secondary vanadium source. Therefore, the binding mechanisms of vanadium in the respective slag minerals must be fundamentally understood to adapt a recovery process, which enables a sufficient yield and is environmentally friendly and resource-saving. This study presents a synchrotron chemical-imaging investigation based on a combined micro X-ray fluorescence, micro X-ray diffraction and micro X-ray absorption near-edge structure analysis, enabling new insights into vanadium incorporation in BOF slags. In contrast to the previously assumed incorporation of vanadium directly into the calcium silicates, it was shown that vanadium accumulates in their boundary regions as tetrahedral V⁵⁺ in a structure deviating from calcium silicates. This structure is most likely a poorly crystalline residuum consisting mainly of calcium, silicon and vanadium (and oxygen) but shows no evidence of a glass phase. Additionally, vanadium occurs as octahedral V⁴⁺ in calcium ferrites and as tetrahedral V⁵⁺ in very small quantities directly in the calcium silicates. The significant enrichment of vanadium in the boundary regions of calcium silicates together with the high oxidations states, resulting in high mobility, can be regarded as advantageous for future recycling strategies.

Biological small-angle X-ray scattering (SAXS) is a versatile and powerful technique for investigating the structural and biophysical properties of biologically and pharmaceutically relevant macromolecules and nanoparticles. SAXS offers detailed insights into macromolecular composition, size, shape and internal structure, while addressing key aspects such as oligomeric state, stability, molecular interactions, and conformational flexibility. Recently, asymmetrical-flow field-flow fractionation (AF4) was successfully coupled to SAXS, enabling online size-based fractionation and analysis of polydisperse samples. This approach allows precise, size-dependent characterization, offering significant advancements in the study of polydisperse systems. We have integrated an AF4 device at the P12 beamline at the European Molecular Biology Laboratory and implemented technical adaptations allowing full automation to make the system suitable for routine user access. We provide streamlined workflows and troubleshooting resources for both novice and advanced SAXS users thereby equipping them with clear guidance on performing AF4-SAXS measurements. The general principles of our set-up are easily adaptable to other beamlines which have integrated (or are planning to integrate) a similar system.

Cavity-based X-ray free-electron lasers (CBXFELs) represent a possible realization of fully coherent hard X-ray sources having high spectral brilliance along with a narrow spectral bandwidth of ∼1-50 meV, a high repetition pulse rate of ∼1 MHz, and good stability. A diagnostic tool is required to measure CBXFEL spectra with meV resolution and high luminosity on a shot-to-shot basis. We have designed a high-luminosity single-shot hard X-ray spectrograph that images 9.831 keV X-rays in a ∼200 meV spectral window with a spectral resolution of a few meV. The spectrograph is designed around angular dispersion of X-rays in Bragg diffraction from crystals. It operates close to design specifications, exhibiting a linear dispersion rate of ∼1.4 µm meV^-1 and a ∼200 meV window of high-fidelity spectral imaging. The experimentally demonstrated spectral resolution is ∼20 meV; this resolution is twice as low as expected from theory primarily because the spectrograph is highly sensitive to crystal angular instabilities. The experiment was performed at the bending magnet X-ray optics testing beamline 1-BM at the Advanced Photon Source.