As part of an effort to establish the principles and application of F K-edge X-ray absorption spectra to complex inorganic systems, the F K-edge spectra of a range of glasses, minerals and synthetic crystalline compounds are presented and discussed in terms of the F environments present. Crystalline fluorides often display richly detailed spectra as a result of the small core-hole broadening at the F K-edge, and the analysis of the spectra is presented by way of examining trends in material structure and bonding, spectral fingerprinting, and linear combination fitting. The benefits and drawbacks of each method of analysis are discussed, and recommendations for collection of high quality spectra are presented. The speciation of F in three oxide glasses is established by comparison of the observed F K-edge spectra with the spectra of suitable crystalline reference material. The F environments determined this way are in excellent agreement with previous works that utilized other methods of probing the F speciation, though in one case ambiguity in the observed spectrum does prevent definitive identification. F K-edge spectra were also calculated using the FEFF software package, with the aim of calculating spectra that reproduce the experimental spectra accurately with a minimum of prior knowledge and assumptions. The spectrum of CaF2 was calculated with a wide range of simulation parameters, and comparisons with experimental data are made to facilitate a simple computational workflow, that is validated by application to the simulation of the spectrum of Ca4Si2O7F2. Observations and recommendations are made that will assist other experimenters in the collection and analysis of future high-quality F K-edge spectra. The data and analyses presented establish F K-edge X-ray absorption spectroscopy as a powerful tool for the characterization of F speciation and environments in complex inorganic materials.
In the context of the global big data deluge, concerted efforts are being made to address the challenges faced by large scientific facilities. These efforts are focused on providing users with the full potential offered by real-time, remote and self-driving experiments, where AI-driven analysis can guide experimental decisions in real time, while ensuring that the data pipelines adhere to the findability, accessibility, interoperability and reuse principles throughout their entire facility lifecycle. Besides all the efforts being made, a user-centric and user-friendly centralization of the overall scientific computing framework at the large scientific facilities remains a work in progress. To address this challenge the Big Data Science Center at the Shanghai Synchrotron Radiation Facility has developed and deployed a centralized, cohesive and user-friendly platform on top of its already existing superfacility framework, which is designed to manage the complete data lifecycle at large scientific facilities. This user-centric platform has transformed the user experience, shifting focus from complex data operations to scientific interpretation. Consequently, the accessibility of the facility to users has been considerably enhanced, thereby expediting the pace at which their discoveries are made.
A silicon carbide (SiC) X-ray beam position monitor is presented, based on a resistive charge-division principle derived from lateral-effect photodiodes and specifically adapted for synchrotron radiation applications. This device, referred to as a resistive X-ray beam position monitor (rXBPM), exploits a free-standing SiC membrane combined with a resistive p+-doped layer, enabling transmission-mode operation while preserving high radiation hardness and mechanical robustness. In contrast to conventional segmented X-ray beam position monitors, whose response depends strongly on the beam spot size and is typically limited to narrow linear regions, the resistive architecture of the rXBPM provides an intrinsically beam-footprint-independent position signal with an extended linear response region. The detector was fabricated using selective electrochemical etching to realize a thin membrane structure and was experimentally characterized at the microfocus beamline (MiFo) in the PTB laboratory at the BESSY II synchrotron facility using 5.4 keV X-rays. An average transmission of approximately 61% was measured, with good spatial uniformity across the membrane area. Raster-scan measurements demonstrate a linear position response over ranges of ±500 µm and ±1 mm around the detector center, with position sensitivities exceeding 0.157 mm-1 and estimated upper-limit noise-equivalent positions of a few micrometres. Three-dimensional COMSOL simulations were used to model charge transport and lateral charge division in the real device geometry, showing excellent agreement with experimental results and confirming the independence of the position sensitivity from the beam spot size over a wide range of operating conditions. These results establish SiC rXBPMs as a compact, beam spot size calibration-free and radiation-hard solution for beam diagnostics at modern synchrotron light sources, with particular relevance for applications requiring large active areas, extended linearity and minimal beam perturbation.
The paper presents a comprehensive description of a new setup implemented and commissioned at the SEXTANTS beamline of Synchrotron SOLEIL for absorption and scattering experiments with X-ray beams carrying an orbital angular momentum, also known as twisted X-ray beams. Two alternative methods have been implemented, based on the use of either spiral zone plates or fork grating devices, and we show how they can be used for both defining and assessing the orbital angular momentum of an X-ray beam. We also demonstrate that cascading multiple devices enables integer operations on the orbital angular momentum of the resulting X-ray beam. Finally, we report the results of the first resonant scattering pilot experiments in transmission and reflection mode, intended to assess the feasibility of future users' measurements. The availability of twisted soft X-rays complements the range of experimental techniques in elastic, resonant and coherent scattering available at the SEXTANTS beamline.
Hierarchical phase-contrast tomography (HiP-CT) was recently developed to enable the ex vivo imaging of human organs at multiple scales from whole organ down to near-cellular resolution in localized regions. Using whole adult human brain imaging as a case study, this article shows the evolution and optimization of this technique from its initial development at the BM05 beamline to its transition and current status at BM18. Thanks to the higher spatial coherence, larger beam size, higher energies and larger propagation distances available at BM18 and due to the European Synchrotron's Extremely Brilliant Source upgrade (ESRF-EBS), this transition resulted in significantly improved data quality, resolution, sensitivity and speed. More recently, the implementation of a new generation of larger sCMOS cameras, helical scanning (including dedicated reconstruction algorithm developments), binning at the chip and projections levels, and the design of high-efficiency optics allowed us to progressively improve the trade-off between dose and image quality, and acquisition time. These advances enable whole-organ imaging at voxel sizes ranging from ∼42 µm to ∼15 µm, with acquisition times reduced from ∼18 h to ∼3-6 h, depending on configuration. These acquisition schemes present the current status of full-organ imaging using HiP-CT and represent the constant efforts for improvement of the technique towards the investigation of human organs in health, disease and ageing.
The structural biology method of X-ray footprinting mass spectrometry (XFMS) is available at two national synchrotron beamlines in the USA: one at the Advanced Light Source (ALS) on the West Coast and the other at the National Synchrotron Light Source II on the East Coast. XFMS is a solution-state technique that utilizes oxidative modifications of proteins at micromolar concentrations in aqueous buffer to extract structural information. X-rays are employed to generate hydroxyl radicals in situ, which covalently modify specific protein side chains. These modifications are subsequently quantified using liquid chromatography and mass spectrometry. Ratiometric changes in modification levels between two protein states (e.g. with and without ligand) generate a relative solvent accessibility map of the protein pairs, which serves to reveal structural features. Up until recently, the XFMS capability was available as part of a shared program at the ALS without a dedicated beamline. In this article, we describe the commissioning of ALS beamline 3.3.1, dedicated to XFMS, including the installation of a new focusing mirror, the design and construction of a new endstation with automated sample handling and exposure capabilities, and the use of accurate empirical dose calculations using Gafchromic film. Finally, we showcase the new beamline capabilities using two protein systems.
In situ observations of high-temperature transformations, not compromised by reactivity with a crucible, have recently become accessible by integrating containerless processing with the time-resolved diffraction of synchrotron X-rays. The presented electromagnetic levitator (EML) has been designed for mobility and ease of operation during beamline experiments while enabling stable processing of a wide range of materials. Developed to work with area detectors, the facility's capabilities are demonstrated by measurements of the structural changes during melting and solidification of pure Fe and Fe-Co samples. The direct observations of the metastable phase formation in the Fe-Co system, accessible through containerless processing, have been accomplished for the first time due to the improved acquisition rate of modern area detectors. The diffraction patterns and associated artifacts characteristic of crystal structure measurements during levitation are examined. Moreover, an analytical description of the measured instrumental resolution of the diffraction setup is presented along with a survey of the corrections and associated measurements necessary for an accurate total scattering analysis of the disordered states, such as liquids or glasses. This provides a base for the conceptual planning of diffraction experiments suitable for various levitation methods, including electrostatic, aerodynamic and acoustic levitation.
A surface-enhanced Raman scattering (SERS) sensor built on a free-standing Au/Cu-covalent organic framework (COF) membrane was developed for the noninvasive Helicobacter pylori detection by quantifying trace ammonia in exhaled breath. The porphyrin-based Cu-COF acts as a multifunctional sensing interface, using its porous structure and accessible porphyrin-Cu coordination sites to efficiently capture and preconcentrate ammonia vapor. The change of intensity of the characteristic SERS peak at the 391 cm-1 Raman peak (ΔI391) shows a good linear relationship with ammonia concentration in the range of 0.5 to 3 ppm, with a limit of detection (LOD) down to 0.5 ppm. The sensor shows good stability and anti-interference ability toward common volatile organic compounds (VOCs) and inorganic gases in breath, allowing rapid detection without complex sample pretreatment. Notably, the introduction of Cu2+ significantly enhanced the crystallinity and structure ordering of the COF membrane, offering a new strategy for metal-ion-mediated structural regulation of 2D COF films. Preliminary clinical blind testing on exhaled breath samples yields a 70% diagnostic accuracy for H. pylori infection, validating the practical potential of this sensor. This work establishes a robust SERS platform for breath biomarker analysis and provides a promising route for noninvasive, real-time, and point-of-care diagnosis of H. pylori infection.
FLASH radiotherapy involves delivering relatively high radiation doses at ultra-high dose rates (UHDRs) that are several orders of magnitude greater than those used in conventional radiotherapy (40 Gy s-1 versus 0.5-5 Gy min-1, respectively). Previous in vivo studies have shown that doses delivered with such UHDRs result in significant tumour killing while having less effect on normal tissues. Most of these in vivo studies were based on the use of charged particles such as electrons and protons. In this study we exposed cells [human epidermal melanocytes (HEM), MM96L melanoma cells, CCD841 colon epithelial cells and CaCo2 colorectal adenocarcinoma cells] grown in vitro to synchrotron-based X-ray beams delivered at either low dose rates or UHDRs to validate the FLASH effect. The FLASH effect that has been reported to occur under hypoxic conditions was also investigated using HEM and MM96L cells. Significant cell killing was observed at 48 h post-irradiation, when the cells were exposed to high dose (≥10 Gy) UHDRs compared with low dose rate beams in both groups of cells. MM96L melanoma cells were ∼10% less resistant to UHDR than were HEM cells. A similar result was observed in CCD841 and CaCo2 cells. When the hypoxic melanocytes (HEM) were exposed to (≥10 Gy) UHDRs a minimal loss of cell viability was observed; however, when hypoxic MM96L cells were irradiated, significant cell losses were observed. These results show that a FLASH effect is evident in these skin and colon cells. Moreover, when MM96L melanoma cells were pretreated with 1 mM gold nanoparticles and exposed to 10 Gy UHDR X-rays there was a 50% dose enhancement observed where only 15% was observed at low dose rates.
Scanning small-angle X-ray scattering (sSAXS) has found multiple applications as a technique to probe the nanostructure in soft tissues and pathologies thereof. However, fresh tissue is fragile and prone to the quick onset of decomposition and autolysis. It lacks the firmness required for uniform and thin sectioning, resulting in the loss of 2D resolution offered by focused X-ray beams, because the signal would be integrated through thick and/or irregular sections. Tissue processing, that includes fixation and embedding, is used to mitigate these issues but can by itself introduce structural changes in the tissues and impede the correct interpretation of sSAXS data. Here the extent of these structural changes in the SAXS signal caused by common tissue preservation methods on the example of skeletal muscle tissue, consisting of both muscle and surrounding connective tissue, was studied. This can guide an informed choice of preservation method tailored for specific experimental requirements. While some techniques performed better than others, all tissue-processing methods induced structural changes to a certain degree. The choice of preservation method is therefore a balance between sectioning requirements and type of tissue used, as well as targeted structural information.
Steroid hormone testing is critical for assessing endocrine function, diagnosing related disorders, and monitoring therapeutic efficacy. However, current mainstream detection methods have limitations. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS), regarded as the gold standard, offers high sensitivity and specificity, it involves complex and time-consuming procedures. Immunoassays such as enzyme-linked immunosorbent assay (ELISA) are simple and fast but are limited by poor throughput for multitarget detection. Therefore, it is crucial to develop an analytical method that streamlines procedures and enables efficient parallel detection of multiple targets. We developed an integrated signal-enhanced aptasensor platform for pooled MS detection of three steroid hormones in serum. It combines aptamer recognition with mass-tag amplification. This approach uses biorecognition instead of chromatography, while mass spectrometry enables simultaneous readout of multiple mass tags from combined samples. The method was evaluated by detecting three steroid hormones (vitamin D, cortisol, and testosterone) in simulated serum samples and human serum samples. The limits of detection (LODs) for these analytes ranged from 0.411 to 6.796 nM, which are below the established clinical cut-off values for each steroid, demonstrating the requisite sensitivity for detection. This integrated signal-enhanced aptasensor outperforms conventional LC-MS/MS in efficiency and ELISA in throughput, enabling the quantification of multiple serum steroid hormones. Therefore, we believe that this method could be potentially useful in the clinical screening of hormone-related disorders and suitable for the analysis of serum.
Powder X-ray diffraction (PXRD) and X-ray absorption near-edge structure (XANES) spectroscopy are complementary techniques for probing cobalt-based (Co-based) Fischer-Tropsch synthesis (FTS) catalyst structures. PXRD reveals crystalline composition, while XANES provides information on coordination geometry and oxidation state. We developed a fast, automated measurement method, based on rapid selection of X-ray beam energy and a dedicated sample environment at beamline ID10 (ESRF), to combine in situ PXRD and XANES in a single experiment. This approach enables simultaneous monitoring of structural and electronic changes in Co-based FTS catalysts under in situ conditions up to 60 bar, offering a comprehensive view of catalyst dynamics.
Simultaneous measurement methods for soft X-ray absorption spectroscopy (XAS) of solid-liquid interfaces and bulk liquids have been developed. The O K-edge XAS spectra of H2O/Au interfaces and bulk H2O were measured using a transmission-type liquid cell, in which the liquid layer was sandwiched between Au/Cr/Si3N4 and Si3N4 membranes. The XAS spectrum of bulk H2O was obtained using the transmission method by controlling the thickness of the liquid layer, whereas the XAS spectrum of the H2O/Au interface was obtained using the electron-yield method by measuring the drain currents from the Au surface after soft X-ray absorption. The XAS spectra of bulk H2O and the H2O/Au interfaces were differentiated to determine the appropriate measurement conditions for the solid-liquid interfaces interfaces.
X-ray diffraction (XRD) combined with in situ mechanical testing is a powerful, non-destructive technique that provides valuable information on structural evolution and defect formation during deformation. Unlike many other characterization methods, XRD does not impose constraints on sample dimensions, does not require a vacuum environment, and can be applied to a wide range of materials with periodic structures. However, such experiments present significant challenges due to the need for precise synchronization between independently controlled systems: one managing mechanical loading and the other handling X-ray measurements. In this work, we report on the successful software-level integration of a nanoindenter control system directly into the beamline control system. This integration enables full control of both mechanical and diffraction measurements from a single user interface, allowing real-time synchronization and automation of complex in situ experiments. We demonstrate the capabilities of this setup through uniaxial compression tests on α-Ti micropillars. Mechanical data from the nanoindenter and XRD patterns were collected simultaneously in an automated mode. Raster scans were performed on the micropillar in its pristine state, at two intermediate deformation stages, and post-mortem. This approach enabled detailed analysis of mechanical behavior and structural evolution under load, illustrating the effectiveness of the integrated system for advanced in situ studies.
Phase contrast and dark-field imaging are relatively new X-ray imaging modalities that provide additional information to conventional attenuation-based imaging. However, this new information comes at the price of a more complex acquisition scheme and optical components. Among the different techniques available, such as grating interferometry or edge illumination, modulation-based and more generally single-mask/grid imaging techniques simplify these new procedures to obtain phase and dark-field images by shifting the experimental complexity to the numerical post-processing side. This family of techniques involves inserting a membrane into the X-ray beam that locally modulates the intensity to create a pattern on the detector which serves as a reference. However, the topological nature of the mask used seems to determine the quality of the reconstructed phase and dark-field images. We present in this article an in-depth study of the impact of the membrane parameters used in a single-mask imaging approach. A spiral topology seems to be an optimum both in terms of resolution and contrast-to-noise ratio compared with random and regular patterns.
Next-generation Mössbauer spectroscopy at synchrotron and X-ray free-electron laser facilities demands rapid, accurate and polarization-aware modeling of nuclear hyperfine interactions. We present a unified analytical framework that provides exact, rotationally invariant expressions for resonance energies and transition probabilities in the presence of simultaneous magnetic dipole and electric quadrupole interactions. Unlike conventional approaches, our method avoids Hamiltonian diagonalization by expressing intensities entirely in terms of hyperfine invariants, enabling efficient global fitting and modeling of hyperfine-interaction distributions in complex materials. We further introduce a quantitative identifiability metric and demonstrate, via Monte Carlo sampling, that polarization control-particularly orthogonal linear polarizations-substantially improves hyperfine-parameter determination. This work offers a mathematically transparent and computationally efficient toolset for modern Mössbauer spectroscopy, accelerating studies of iron-based compounds and magnetic, electronic and structural order under extreme conditions and at nanoscale geometries.
Infrared and terahertz spectroscopy performed at synchrotron facilities offers unique opportunities for probing matter under extreme and well controlled conditions. At the AILES beamline of Synchrotron SOLEIL, two complementary experimental setups have recently been developed to enable spectroscopy of submillimetric samples across a broad range of temperatures and pressures. These platforms operate from 10 K to 600 K and from vacuum up to 100 GPa, while accommodating a variety of sample environments, including liquid cells, diamond anvil cells and uniaxial strain devices. Combined with the high brilliance and stability of synchrotron radiation and advanced detection schemes, these setups are particularly suited for in situ and operando investigations, allowing real-time monitoring of structural changes, phase transitions and reaction dynamics under external stimuli. Their performance is illustrated through far-infrared measurements of water and ice over different thermodynamic states, demonstrating sensitivity to structural reorganizations and hydrogen-bond dynamics. These developments significantly expand the experimental capabilities of the AILES beamline and provide versatile tools for a wide user community, opening new perspectives for studies of functional materials, molecular systems and emerging phenomena under extreme conditions.
This study represents the first feasibility demonstration of hyperspectral X-ray absorption near-edge structure (XANES) mapping performed using a full-field fluorescence imaging approach. This method may be useful in many research fields for determining the spatial distributions of the different oxidation states of an element present at low concentration in X-ray beam-sensitive samples. It was demonstrated that this approach could be easily performed using a full-field imaging method where a Fresnel zone plate (FZP) was employed as a coded aperture, which represented a practical, fast and dose-efficient alternative to the raster-scanning technique, when these two approaches were tested at a beamline not dedicated to X-ray imaging. The basic form of the reconstruction algorithm, which was derived from inline holography, was optimized. This enabled the spatial resolution and overall quality of the reconstructed image to be improved. The ∼62 µm spatial resolution experimentally achieved may be further optimized to about 5 µm using a smaller FZP and larger detector than those used in this investigation. The XANES spectra corresponding to the main chemical species present in the sample, obtained from the tested hyperspectral spectroscopy approach, did not exactly match those expected, as they depended on several empirical processing steps. While these results can be further improved by optimizing the linearity of the detector output via pile-up corrections, further work is needed to establish robustness against variations in masking, background treatment, and intensity-correction choices, especially for studying diluted specimens whose corresponding pixel intensities are similar to those of the background.
In this article, we present the experimental protocol and data-processing framework for megahertz X-ray Photon Correlation Spectroscopy (MHz-XPCS) experiments on soft matter samples implemented at the Materials Imaging and Dynamics (MID) instrument of the European X-ray Free-Electron Laser (EuXFEL). Due to the introduction of a standard configuration and the implementation of a highly automated data-processing pipeline, MHz-XPCS measurements can now be conducted and analyzed with minimal user intervention. A key challenge lies in managing the extremely large data volumes generated by the Adaptive Gain Integrating Pixel Detector (AGIPD) - often reaching several petabytes within a single experiment. We describe the technical implementation, discuss the hardware requirements related to effective parallel data processing and propose strategies to enhance data quality, in particular related to data reduction strategies and an improvement of the signal-to-noise ratio. Finally, we address strategies for making the processed data FAIR (Findable, Accessible, Interoperable, Reusable), in alignment with the goals of the DAPHNE4NFDI project.
Angle-resolved photoemission spectroscopy (ARPES) was developed in the 1970s to 1990s as a momentum-resolved probe of the electronic structure of solids, with its basic principles summarized in early seminal works and classic reviews. The basic ARPES result is currently almost exclusively associated with the two-dimensional intensity distribution with coordinate axes labeled as `Binding energy' and `Momentum'. Such datasets are usually directly compared with band structure calculations along high symmetry directions of the Brillouin zone. Here it is shown that this is the result of an oversimplified treatment of the ARPES data leading to incorrect interpretations of the experimental results. Practical ways of how to avoid this in both data collection and analysis are suggested.