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We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. By searching for coherent variations in the recorded clock frequency comparisons across the network, we significantly improve the constraints on transient variations of the fine structure constant. For example, we constrain the variation to |δα/α| < 5 × 10−17 for transients of duration 103 s. This analysis also presents a possibility to search for dark matter, the mysterious substance hypothesised to explain galaxy dynamics and other astrophysical phenomena that is thought to dominate the matter density of the universe. At the current sensitivity level, we find no evidence for dark matter in the form of topological defects (or, more generally, any macroscopic objects), and we thus place constraints on certain potential couplings between the dark matter and standard model particles, substantially improving upon the existing constraints, particularly for large (≳104 km) objects.

This study presents a comprehensive computational framework for reproducing the full X‐ray absorption fine structure (XAFS) through quantum‐chemical simulations. The near‐edge region is accurately captured using an efficient implementation of time‐dependent density‐functional perturbation theory applied to core excitations, while ab initio molecular dynamics provides essential sampling of core‐excitation energies and interatomic distance distributions for interpreting extended X‐ray absorption fine structure (EXAFS) features. Owing to the efficiency of the approach, the total spectrum can be decomposed into contributions from bulk, defective, and surface environments, which commonly coexist in experimental systems. The methodology is demonstrated for sodium at the Na K‐edge in NaCl, where the predicted spectra show good agreement with experimental measurements on thin‐film samples. This strategy offers a practical route to generating chemically specific XAFS cross‐section data for elements and species that remain challenging to characterize experimentally, thereby enabling deeper insights into materials of technological importance. A computational framework is presented for reproducing the full X‐ray absorption fine structure (XAFS) through quantum‐chemical simulations. The near‐edge region is captured using time‐dependent density‐functional perturbation theory applied to core excitations, while ab initio molecular dynamics provides sampling of core‐excitation energies and interatomic distance distributions for interpreting extended X‐ray absorption fine structure (EXAFS) features.

Revealing and clarifying the chemical reaction processes and mechanisms inside the batteries will bring a great help to the controllable preparation and performance modulation of batteries. Advanced characterization techniques based on synchrotron radiation (SR) have accelerated the development of various batteries over the past decade. In situ SR techniques have been widely used in the study of electrochemical reactions and mechanisms due to their excellent characteristics. Herein, the three most wide and important synchrotron radiation techniques used in battery research were systematically reviewed, namely X‐ray absorption fine structure (XAFS) spectroscopy, small‐angle X‐ray scattering (SAXS), and X‐ray diffraction (XRD). Special attention is paid to how these characterization techniques are used to understand the reaction mechanism of batteries and improve the practical characteristics of batteries. Moreover, the in situ combining techniques advance the acquisition of single scale structure information to the simultaneous characterization of multiscale structures, which will bring a new perspective to the research of batteries. Finally, the challenges and future opportunities of SR techniques for battery research are featured based on their current development. Advanced characterization techniques contribute to revealing and clarifying the chemical reaction processes and mechanisms inside the batteries. This review comprehensively overviews the recent advances in battery characterization using in situ synchrotron X‐ray absorption fine structure (XAFS), small‐angle X‐ray scattering (SAXS), X‐ray diffraction (XRD), and their combining techniques.

Anisotropic exchange splitting in semiconductor quantum dots results in bright-exciton fine-structure splitting important for quantum information processing. Direct measurement of fine-structure splitting usually requires single/few quantum dots at liquid-helium temperature because of its sensitivity to quantum dot size and shape, whereas measuring and controlling fine-structure splitting at an ensemble level seem to be impossible unless all the dots are made to be nearly identical. Here we report strong bright-exciton fine-structure splitting up to 1.6 meV in solution-processed CsPbI 3 perovskite quantum dots, manifested as quantum beats in ensemble-level transient absorption at liquid-nitrogen to room temperature. The splitting is robust to quantum dot size and shape heterogeneity, and increases with decreasing temperature, pointing towards a mechanism associated with orthorhombic distortion of the perovskite lattice. Effective-mass-approximation calculations reveal an intrinsic ‘fine-structure gap’ that agrees well with the observed fine-structure splitting. This gap stems from an avoided crossing of bright excitons confined in orthorhombically distorted quantum dots that are bounded by the pseudocubic {100} family of planes. Halide perovskites feature highly dynamic lattices, but their impact on exciton fine structure remains unexplored. Here, the authors show that these lattices lead to a bright-exciton fine structure gap, enabling observation of quantum beats in a non-uniform ensemble.

Diamond-like carbon (DLC) films have been extensively applied in industries owing to their excellent characteristics such as high hardness. In particular, there is a growing demand for their use as protective films for mechanical parts owing to their excellent wear resistance and low friction coefficient. DLC films have been deposited by various methods and many deviate from the DLC regions present in the ternary diagrams proposed for sp3 covalent carbon, sp2 covalent carbon, and hydrogen. Consequently, redefining the DLC region on ternary diagrams using DLC coatings for mechanical and electrical components is urgently required. Therefore, we investigate the sp3 ratio, hydrogen content, and other properties of 74 types of amorphous carbon films and present the classification of amorphous carbon films, including DLC. We measured the sp3 ratios and hydrogen content using near-edge X-ray absorption fine structure and Rutherford backscattering-elastic recoil detection analysis under unified conditions. Amorphous carbon films were widely found with nonuniform distribution. The number of carbon atoms in the sp3 covalent carbon without bonding with hydrogen and the logarithm of the hydrogen content were inversely proportional. Further, we elucidated the DLC regions on the ternary diagram, classified the amorphous carbon films, and summarized the characteristics and applications of each type of DLC.

Extended X‐ray absorption fine structure (EXAFS) is a comprehensive and usable method for characterizing the structures of various materials, including radioactive and nuclear materials. Unceasing discussions about the interpretation of EXAFS results for actinide nanoparticles (NPs) or colloids were still present during the last decade. In this study, new experimental data for PuO2 and CeO2 NPs with different average sizes were compared with published data on AnO2 NPs that highlight the best fit and interpretation of the structural data. In terms of the structure, PuO2, CeO2, ThO2, and UO2 NPs exhibit similar behaviors. Only ThO2 NPs have a more disordered and even partly amorphous structure, which results in EXAFS characteristics. The proposed new core‐shell model for NPs with calculated effective coordination number perfectly fits the results of the variations in a metal–metal shell with a decrease in NP size. New experimental EXAFS results for PuO2 and CeO2 nanoparticles in the size range of 2 nm were compared with published data for other lanthanide and actinide dioxides. A conceptual core‐shell model with a calculated effective coordination number is proposed to fit the changes in EXAFS.

The development of advanced catalysts for various electrochemical reactions necessitates precise characterization of their structure and dynamic evolution. This study introduces an innovative electrochemical cell tailored for operando X‐ray characterizations, including X‐ray diffraction (XRD) and X‐ray absorption fine structure (XAFS). The cell features an adjustable aqueous electrolyte window to reduce X‐ray signal absorption and an integrated flow system for efficient removal of gas products. This design enables simultaneous XRD and XAFS measurements in both fluorescence and transmission modes. Using LiCoO2 as a model oxygen evolution reaction catalyst, operando measurements reveal structural transformations during the reaction. This device will aid in the exploration of catalyst mechanisms and the development of high‐performance catalysts. An innovative electrochemical cell is introduced, optimized for in situ X‐ray diffraction and X‐ray absorption spectroscopy studies of electrocatalysts, featuring an adjustable aqueous electrolyte window to minimize X‐ray absorption and a flow system for efficient gas product removal during operando testing.

The electrocatalytic reduction of CO 2 to HCOOH (ERC-HCOOH) is one of the most feasible ways to alleviate energy crisis and solve environmental problems. Nevertheless, it remains a challenge for ERC-HCOOH to maintain excellent activity and selectivity in a wide potential window. Herein, ultra-thin flower-like Bi 2 O 2 CO 3 nanosheets (NSs) with abundant Bi-O structures were in situ synthesized on carbon paper via topological transformation and post-processing. Faraday efficiency of HCOOH (FE HCOOH ) reached 90% in a wide potential window (−1.5 to −1.8 V vs. Ag/AgCl). Significantly, excellent FE HCOOH (90%) and current density (47 mA·cm −2 ) were achieved at −1.8 V vs. Ag/AgCl. The X-ray absorption fine structure (XAFS) combined with density functional theory (DFT) calculation demonstrated that the excellent performance of Bi 2 O 2 CO 3 NS was attributed to the abundant Bi-O structures, which was conducive to enhancing the adsorption of CO 2 * and OCHO* intermediates and can effectively inhibit hydrogen evolution. The excellent performance of Bi 2 O 2 CO 3 NS over a wide potential window could provide new insights for the efficient electrocatalytic conversion of CO 2 .

Lattice distortions constitute one of the main features characterizing high entropy alloys. Local lattice distortions have, however, only rarely been investigated in these multi-component alloys. We, therefore, employ a combined theoretical electronic structure and experimental approach to study the atomistic distortions in the FeCoNiCrMn high entropy (Cantor) alloy by means of density-functional theory and extended X-ray absorption fine structure spectroscopy. Particular attention is paid to element-resolved distortions for each constituent. The individual mean distortions are small on average, <1%, but their fluctuations (i.e., standard deviations) are an order of magnitude larger, in particular for Cr and Mn. Good agreement between theory and experiment is found.

A plug‐flow fixed‐bed cell for synchrotron powder X‐ray diffraction (PXRD) and X‐ray absorption fine structure (XAFS) idoneous for the study of heterogeneous catalysts at high temperature, pressure and under gas flow is designed, constructed and demonstrated. The operating conditions up to 1000°C and 50 bar are ensured by a set of mass flow controllers, pressure regulators and two infra‐red lamps that constitute a robust and ultra‐fast heating and cooling method. The performance of the system and cell for carbon dioxide hydrogenation reactions under specified temperatures, gas flows and pressures is demonstrated both for PXRD and XAFS at the P02.1 (PXRD) and the P64 (XAFS) beamlines of the Deutsches Elektronen‐Synchrotron (DESY). A plug‐flow fixed‐bed cell for synchrotron powder X‐ray diffraction (PXRD) and X‐ray absorption fine‐structure (XAFS) idoneous for the study of heterogeneous catalysts at high temperature, pressure and under gas flow is designed, constructed and demonstrated. The operating conditions up to 1000°C and 50 bar are ensured by a set of mass flow controllers, pressure regulators and two infra‐red lamps that constitute a robust and ultra‐fast heating and cooling method.