Recent lbnl_es_als items

Electron-doping-induced destabilization of the dimerized insulating state in monolayer IrTe 2

Wed, 17 Jun 2026 00:00:00 +0000

The ability to tune the electronic phases of two-dimensional (2D) materials through external perturbations provides a powerful route to engineer functional nanoscale systems. In particular, the ground state of monolayer... The ability to tune the electronic phases of two-dimensional (2D) materials through external perturbations provides a powerful route to engineer functional nanoscale systems. In particular, the ground state of monolayer (ML) 1T-IrTe 2 is highly sensitive to the interplay between local chemical bonding and global electronic topology, leading to a unique 2 x 1 dimerized insulating phase. Here, we present an angle-resolved photoemission study on the evolution of the electronic structure in ML IrTe 2 induced by in situ Rb adsorption. We find that Rb adsorption suppresses the 2 x 1 dimerized phase in ML IrTe 2 , inducing a clear insulator-to-metal transition. This transition is characterized by a reconstruction of the band topology toward a bilayer-like metallic...

Evidence for Thermodynamically Stable “On-Top” Sulfur Divacancy in Monolayer WS2

Tue, 16 Jun 2026 00:00:00 +0000

Chalcogen vacancies in monolayer transition metal dichalcogenides (TMDs), such as WS2, play a crucial role in various applications ranging from optoelectronics and catalysis to quantum information science (QIS), making their identification and control essential. This study focuses on the WS2 single vacancy and vacancy pairs. Using first-principles computations, we investigate their thermodynamic stabilities and electronic structures. We identify an ”on-top” divacancy configuration where two vacancies sit on top of each other to be the only energetically stable complex with a binding energy of 160 meV. We compute a small difference in electronic structure with a shift of the unoccupied state by 140 meV for the divacancy complex and make note of a similar shift observed experimentally.

An Atom-Precise Approach to Damp First-Order Phase Transitions and Its Implications for Neuromorphic Signal Processing

Thu, 11 Jun 2026 00:00:00 +0000

Neuromorphic computing inspired by mammalian intelligence aims to emulate the nonlinear dynamics of biological neurons and synapses to achieve fast, low-energy, and highly efficient information processing. Brain-inspired computing relies on the design and discovery of materials exhibiting nonlinear current-voltage profiles, frequently underpinned by electronic state transitions, to achieve spiking neurons and dynamically tunable synapses. A signature challenge in the design of artificial neurons is controlling the steepness of first-order transitions in active elements, as abrupt transitions are at risk of driving unstable voltage and temperature oscillations, which result in catastrophic device failure. A critical knowledge gap is the lack of structure-function correlations mapping the composition and atomistic structure of crystalline solids to nonlinear dynamical response characteristics. Here, we address the key question of how modification of atomistic structure correlates...

Measurement report: Role of organic coating and chemical composition on ice nucleation potential of atmospheric particles in European Arctic

Wed, 10 Jun 2026 00:00:00 +0000

Abstract. Understanding the ice nucleation (IN) potential of Arctic aerosols is critical for predicting their influence on cloud formation and water cycles in this vulnerable region. This study investigates the role of particle composition, organic coatings, and aerosol sources in modulating ice nucleating particle (INPs) abundance across five aerosol samples collected at the Gruvebadet Observatory Station in Ny-Ålesund, Svalbard. The IN potential of Arctic aerosol particles was studied by investigating chemical, morphological, and INP abundance measurements. Single-particle analyses revealed distinct differences in mixing state, organic volume fraction (OVF), and organic coating morphology across samples. OVF distributions were linked to particle origin, with marine-influenced Na-rich particles often exhibiting thin organic coatings, while long-range transported particles showed thicker organic coatings. Biogenic contributions, though variable, were linked to heat-sensitive INPs,...

Chemistry of Sugar Formation in the Gas Phase: Following the Activated Aldehyde

Tue, 9 Jun 2026 00:00:00 +0000

Sugars are produced by living organisms, and are required building blocks for life as we know it, which raises the foundational question of how sugars formed in a prebiotic environment. The abiotic formose reaction produces sugars from formaldehyde, but our understanding of its initiation step remains murky, with chemists invoking the concept of an "activated aldehyde" to seed this reaction. Singlet hydroxycarbenes, high-energy isomers of aldehydes, were recently reported to facilitate sugar formation under cold, nonaqueous conditions relevant to interstellar environments. We generate singlet methylhydroxycarbene (¹CH₃-C̈-OH) from the photodissociation of pyruvic acid and experimentally measure its gas-phase reaction with d₄-acetaldehyde using multiplexed photoionization mass spectrometry. The C₄H₄D₄O₂ isomer d₄-acetoin is the sole product, which we kinetically link to the reactant...

The Chemistry of Carbenes: New Insights from the Gas Phase

Tue, 9 Jun 2026 00:00:00 +0000

This review describes insights obtained from recent studies of unimolecular and bimolecular reactions of small carbenes in the gas phase and cryogenic environments. Following a description of what determines the singlet-triplet splitting in carbenes, we discuss the challenges involved in producing carbenes in concentrations sufficient for studying their reactions. We document the methods developed for their preparation and the array of spectroscopic techniques available for their characterization. The review emphasizes recent progress in studies of hydroxycarbenes and small alkyl carbenes that easily isomerize to more stable isomers. The studies of unimolecular reactions of hydroxycarbenes show how quantum mechanical tunneling determines their lifetimes. A new carbonyl-ene mechanism has been demonstrated in the biomolecular reactions of hydroxymethylene and methylhydroxycarbenes. We evaluate the impact of these new results on chemical processes relevant to atmospheric, planetary,...

Celebrating 25 Years of Scientific Discoveries in Physical Chemistry Supported by the ACS Petroleum Research Fund

Tue, 9 Jun 2026 00:00:00 +0000

Celebrating 25 Years of Scientific Discoveries in Physical Chemistry Supported by the ACS Petroleum Research Fund

Transient Pulse-Response Time-of-Flight Mass Spectrometry for Complex, Deactivating Heterogeneous Catalytic Systems: Application to Ethane Dehydroaromatization

Tue, 9 Jun 2026 00:00:00 +0000

The study of complex, multistep bond-forming and -breaking reactions in heterogeneous catalytic systems often encounters challenges associated with the involvement of large numbers of intermediates among branching pathways. Kinetic information obtained from traditional steady-state measurements can be complemented with that from time-resolved methods to uncover details of the underlying chemistry. Herein, we describe an approach for tracking the complete time-resolved chemical composition (ca. 4–200 u) of a reactor effluent in response to a reactant pulse. We use a six-port rotary valve with a metered sampling loop to pulse reactants at ambient pressure into a flow reactor packed with a catalyst bed within the isothermal region of a heated furnace. The temporal evolution of effluent species is tracked using time-resolved molecular-beam time-of-flight mass spectrometry. We highlight the possibilities that this method has to offer by studying the complex bifunctional mechanism of...

High-Resolution Time-Resolved PEPICO with Tunable Vacuum Ultraviolet Photoionization

Tue, 9 Jun 2026 00:00:00 +0000

Recently we presented a new time-resolved, double-imaging photoelectron photoion coincidence (i²PEPICO) spectrometer for the study of chemical reactions using fixed frequency, single-photon vacuum ultraviolet ionization. Here we describe new capabilities and insights from this instrument when coupled with tunable ionizing radiation. We interrogate the gas expansion dynamics of a side-sampled chemical reactor tube, revealing clear evidence for viscous flow in the expansion before ionization. Cation imaging can be used to restrict detected signal to only the direct molecular beam, removing contributions from background and reflected gases. We characterize the peak shape and mass resolution of the instrument, provide new insight and clarification regarding collection efficiencies, and consider the noise sources and resulting signal-to-noise in PEPICO experiments. We quantify the temporal instrument response function and show that velocity map imaging of cations...

Fluoroform (CHF3) Production from CF3CHO Photolysis and Implications for the Decomposition of Hydrofluoroolefins and Hydrochlorofluoroolefins in the Atmosphere

Tue, 9 Jun 2026 00:00:00 +0000

Hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are the leading synthetic replacements for compounds successively banned by the Montreal Protocol and amendments. HFOs and HCFOs readily decompose in the atmosphere to form fluorinated carbonyls, including CF₃CHO in yields of up to 100%, which are then photolyzed. A long-standing issue, critical for the transition to safe industrial gases, is whether atmospheric decomposition of CF₃CHO yields any quantity of CHF₃ (HFC-23), which is one of the most environmentally hazardous greenhouse gases. This comprehensive experimental investigation employs purpose-built photoionization mass spectrometry, Fourier-transform infrared, and microwave spectroscopy techniques and confirms production of CHF₃ following excitation at a tropospherically relevant wavelength (λ = 308 nm) and under atmospheric pressure conditions. Pressure-dependent CHF₃ quantum (Φ) and molar (Y)...

An interactive machine learning platform for analyzing multi-particle coincidence data from cold target recoil ion momentum spectroscopy

Thu, 4 Jun 2026 00:00:00 +0000

We present SCULPT (Supervised Clustering and Uncovering Latent Patterns with Training), a comprehensive software platform for analyzing tabulated high-dimensional multi-particle coincidence data from Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) experiments. The software addresses critical challenges in modern momentum spectroscopy by integrating advanced machine learning techniques with physics-informed analysis in an interactive web-based environment. SCULPT implements uniform manifold approximation and projection for non-linear dimensionality reduction to reveal correlations in high-dimensional data. We also discuss potential extensions to deep autoencoders for feature learning and genetic programming for automated discovery of physically meaningful observables. A novel adaptive confidence scoring system provides quantitative reliability assessments by evaluating user-selected clustering quality metrics with predefined weights that reflect each metric's robustness....

Plasmonic polaron in self-intercalated 1T-TiS2

Wed, 3 Jun 2026 00:00:00 +0000

Electron-boson coupling is central to a comprehensive understanding of the diverse physical phenomena emerging from many-body interactions. Yet less attention has been paid to how plasmons, collective bosonic modes of electron density oscillation, interact with conduction electrons and how external parameters can tune this interaction. Here, we present a clear display of composite quasiparticles stemming from electron-plasmon coupling, known as the plasmonic polaron, in self-intercalated 1T-TiS2, by using angle-resolved photoemission spectroscopy (ARPES), high-resolution electron energy loss spectroscopy (HR-EELS) and first-principles calculations. The single particle spectral function exhibits a distinctive plasmon-loss satellite with the same characteristic energy scale determined by HR-EELS measurements. The bosonic energy scale of plasmonic polaron is tunable by controlling charge carrier density and temperature, distinguishing itself from conventional polarons arising from...

Modulating coordinate site occupancy in high-entropy spinel electrocatalysts

Wed, 27 May 2026 00:00:00 +0000

High entropy spinel oxides provide a versatile platform for electrocatalysis because multiple metal cations can be incorporated into a single crystalline lattice, enabling tunable electronic structures. However, controlling how these cations distribute between tetrahedral and octahedral coordination sites remains a major challenge, limiting rational catalyst design. Here, we modulate cation coordination site occupancy between tetrahedral and octahedral sites in a Co–Fe–Cr–Mn–Ni framework by introducing a sixth cation (Zn, Ga, Mg, or Al) with distinct site preference energies. Using density functional theory, synchrotron X-ray absorption spectroscopy, and magnetic circular dichroism, we demonstrate that Zn preferentially occupies tetrahedral sites, driving increased octahedral occupancy of cobalt. This redistribution increases the population of octahedrally coordinated cobalt in mixed oxidation states, enhances electrical conductivity, and improves oxygen evolution reaction activity....

Zircon Constraints on the Eruptive Sequence and Magma Evolution of Rhyolites at South Sister Volcano, Oregon

Thu, 21 May 2026 00:00:00 +0000

Abstract We present 230 Th‐ 238 U crystallization ages and trace element compositions for zircons spanning the late Pleistocene to Holocene rhyolite eruptive record at South Sister volcano in the central Oregon Cascade Range. Most zircon ages are between 100 and 20 ka, with very few in secular equilibrium (>350 ka). The weighted mean of zircon ages for the two oldest South Sister rhyolites, 31.5 ± 2.1 and 39.1 ± 2.4 ka, are significantly younger than the associated 40 Ar/ 39 Ar ages, 47.4 ± 9.7 and 51.4 ± 9.7 ka. We propose that these 40 Ar/ 39 Ar dates, performed on plagioclase separates, are compromised by a subtle amount of excess Ar and therefore the younger weighted mean zircon ages yield more reliable eruption ages. These results imply that the interval of rhyolite eruption at South Sister during the late Pleistocene was both shorter and more productive than previously thought and that eruption at South Sister...

Design and commissioning of a new synchrotron beamline dedicated to X‐ray footprinting mass spectrometry

Thu, 21 May 2026 00:00:00 +0000

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...

The Magmatic‐Hydrothermal System of the Three Sisters Volcanic Cluster, Oregon, Imaged From Field Gravity Measurements

Thu, 21 May 2026 00:00:00 +0000

Abstract From 2019 to 2024, gravity surveys were conducted at the Three Sisters volcanic cluster (TSVC), measuring 246 gravity sites using a spring relative gravimeter. We calculated the residual Bouguer anomaly and identified three main zones with negative anomalies, ranging from −4 to −8 mGal, located southwest and west of South Sister, within an area that has been uplifting for the past two decades. After inversion, we obtain a 3D density model of the subsurface and identify low‐density bodies extending from the surface down to 3 km. We estimate a total of 15 k of crustal bodies with density close to 2 g/ that could store up to 5 k of water, forming an extensive hydrothermal system beneath the TSVC. We explore the possible combinations of melt compositions and temperatures that could create a bulk density close to our reference crustal density (2.5 g/) using MELTS thermodynamic simulations. Our results indicate that a magmatic mush with as little...

Trivalent titanium in high-titanium lunar ilmenite

Fri, 15 May 2026 00:00:00 +0000

Lunar mare basalts are often rich in titanium, hosted predominantly within the mineral ilmenite (Fe2+Ti4+O3). Here, we examine ilmenite in a ~ 3.8 billion-year-old mare basalt (Apollo rock 75035) using high-resolution electron microscopy and electron energy loss spectroscopy. A key finding is that 75035 ilmenite is itself enriched in Ti, beyond the end member of the conventional solid solution series. Using energy loss near-edge spectroscopy, we determine that the excess Ti is trivalent, with Ti3+ accounting for 13% of the total Ti content. This discovery confirms the presence of trivalent Ti in lunar ilmenite, long hypothesized based on the Moon’s reducing environment. Accounting for the change in implied stoichiometry, a review of literature data suggests that Ti3+ may be present in ilmenite across a wide range of lunar samples. We extrapolate known relationships from the literature to connect Ti3+ to redox conditions, estimating the oxygen fugacity during crystallization...

Single domain spectroscopic signatures of a magnetic kagome metal

Thu, 14 May 2026 00:00:00 +0000

Magnetic kagome metals host complex electronic states and real-space magnetic textures, but their small and temperature-dependent magnetic domains make experimental access difficult. Here we show that micro-focused circular-dichroic photoemission spectroscopy enables spectroscopic access to individual magnetic domains in the kagome metal DyMn6Sn6 at low temperature. By tuning to element-specific electronic states, we image domain contrast associated with Dy 4f levels and detect corresponding signatures from Mn core states. The energy dependence of the dichroic response is consistent with modeling and indicates ferrimagnetic alignment between Dy and Mn local moments. Measurements of Mn 3d-derived valence bands, supported by first-principles calculations, reveal features related to orbital magnetization. These results establish element- and orbital-resolved spectroscopy of single magnetic domains and enable studies of magnetic textures and electronic structure in complex magnetic...

Symmetry-Protected Moiré Band Engineering and Enhanced Electron–Phonon Coupling in Xe/Bi2Se3 Superlattices: Path to Topological Superconductivity

Thu, 14 May 2026 00:00:00 +0000

Observation of superconductivity, magnetism, and correlated insulating phases driven by the moiré potential in twisted graphene bilayer has opened the exciting new field of "twistronics". Even richer physics is expected if moiré superlattice could be generated on topological insulators; however, until now, experimental studies have been scarce. Here, we demonstrate topological moirés generated by adsorbing a monolayer of noble gas on a topological insulator. By angle-resolved photoemission spectroscopy, we show that the moiré potential replicates the topological surface state and affects it in a way fundamentally different from the trivial states. Replicated Dirac cones generally avoid crossings, except at the time-reversal invariant momenta that remain gapless. This creates van Hove singularities at the moiré Brillouin zone corners, providing the mechanism of enhancing correlations. Indeed, we observe a strong enhancement of the electron-phonon coupling strength that, if properly...

Improvements in optical metrology for high-performance variable-line-spacing x-ray gratings

Wed, 13 May 2026 00:00:00 +0000

We discuss a project to develop a precision metrology system for variable-line-spacing x-ray gratings using interferometric microscopes. We are developing test standards and calibration techniques to measure and correct for geometrical distortion and blur, and data processing techniques to combine multiple measurements and measure line spacing with high accuracy.

Comparison of theory with the experimental characterization of the spatial frequency response of interferometers using a binary pseudo-random array sample

Wed, 13 May 2026 00:00:00 +0000

Experimental evaluations of the surface height response of an interference microscope using a binary pseudo-random array test sample are compared with a theory based on a Fourier optics model. Measurements of key instrument characteristics, including the illumination, imaging, and obscuring apertures of three different Mirau objectives, support the theoretical calculations. Agreement between experimental and theoretical modeling confirms the predictability of the spatial frequency response for the purpose of specification and optimization of instrument configuration for specific metrology tasks. The results also provide confidence in methods of compensating for the decrease in instrument response with spatial frequency.

The Transition From Melt Accumulation to Eruption Initiation Recorded by Orthopyroxene Fe‐Mg Diffusion Timescales in Late Holocene Rhyolites, South Sister Volcano, Oregon Cascade Range

Tue, 5 May 2026 00:00:00 +0000

Abstract South Sister volcano, Oregon Cascade Range, USA, has repeatedly erupted rhyolite since ca. 40 ka. The youngest such eruptions are the ca. 2 ka Rock Mesa and Devils Chain rhyolites, erupted several hundred years apart from two multi‐vent complexes separated by 3–6 km. Fe‐Mg interdiffusion models of orthopyroxene rims from both rhyolites produce timescales up to several‐thousand years, but dominantly decades‐to‐centuries. Notably, the timescales of step‐normal zoned orthopyroxene rims (i.e., normally zoned with a steep chemical gradient) from the Rock Mesa rhyolite are longer than those of reversely zoned crystals, whereas the Devils Chain produced mostly decadal timescales for both zoning types. Despite the proximity and broadly similar products of these episodes, their respective timescales indicate distinct sequences of events leading up to each eruption. The Rock Mesa timescales record centuries of magma chamber growth followed by decades of predominantly...

Navigating the research landscape for hyper-NA EUV lithography and future patterning technologies

Wed, 29 Apr 2026 00:00:00 +0000

Hyper-Numerical Aperture (Hyper-NA) Extreme Ultraviolet (EUV) lithography is gathering growing support as the technology of choice to sustain the dimensional scaling trajectory of Moore's Law. This transition, which targets resolution down to 5 nm, necessitates several research advances across several key lithography areas, such as patterning materials, imaging with polarization control, and the optimization of the mask structure. In this paper, we briefly review the historical role of the government-industrial partnerships enabling Center for X-Ray Optics (CXRO) pathfinding research for prior EUV lithography generations. We also highlight the role of the Department of Energy's Energy Frontier Research Center (EFRC) on High-Precision Patterning Science (CHiPPS) as a critical initiative to fundamentally address the pervasive stochastic challenges in materials science that limit the RLS (Resolution, Sensitivity, Line Edge Roughness) tradeoff, charting a path toward the Angstrom...

Spin Texture Control and Magnetic Gap Engineering in a Ferromagnetic Insulator–Topological Insulator Sandwiched Heterostructure

Fri, 24 Apr 2026 00:00:00 +0000

Quantum materials that combine magnetism with topological order are emerging as key platforms for next-generation spintronics and low-energy electronics. They enable the realization of emergent quantum phenomena, such as the quantum anomalous Hall effect and axion insulator states. The ferromagnetic insulator (FMI)/topological insulator (TI)/FMI sandwich structure of a single-septuple layer (1SL) MnBi₂Te₄/four-quintuple layer (4QL) Bi₂Te₃/1SL MnBi₂Te₄ holds great potential to achieve such desirable quantum phenomena at an elevated temperature, owing to its large Dirac point band gap and high Curie temperature. Here, spin- and angle-resolved photoemission spectroscopy (spin-ARPES) is employed to directly verify that the band gap arises from broken time-reversal symmetry via proximity-driven magnetization. This study demonstrates direct control of the spin state via external magnetic fields and unambiguously confirms...

Optimizing microfluidic flow cell geometry for in situ resonant soft X-ray characterization of molecular nanostructures

Fri, 24 Apr 2026 00:00:00 +0000

Liquid-phase resonant soft X-ray scattering (LP-RSoXS) is an emerging label-free technique to probe chemically resolved nanostructures of molecular or hybrid materials in liquid environments. Still, quantitative analysis is hindered by the pressure-induced deformation of thin silicon nitride (SiN) membranes used as windows in microfluidic flow cells, which attenuates the signal in nonlinear ways, making experimental optimization difficult. Here, we directly characterize this deformation under experimental conditions for a variety of cell configurations. We use this to develop a predictive model that combines transmission effects of SiN bowing, incident X-ray beam profiles, and material-dependent resonant scattering cross sections to simulate the effective scattering intensity at the detector across the carbon K-edge. Maps of the total signal across the flow cell window reveal that increasing the window width and polymer concentration shifts the anisotropic intensity distributions...

Organic colloid composition in variable-redox porewaters within a mountainous floodplain

Fri, 24 Apr 2026 00:00:00 +0000

Redox gradients, often driven by changes in sediment moisture levels in porous, heterogeneous groundwater systems, create dynamic conditions that may promote the production and transport of colloids within natural waters. While much research has focused on the inorganic composition of colloids, the organic composition remains less well understood. Organic matter (OM) in colloids may associate with minerals, complex metal ions, and serve as an electron donor for microbial respiration; therefore, its composition is of high interest. We examined the composition of porewater OM along a redox gradient in a riparian soil located along the Slate River in Crested Butte, Colorado, USA as a function of depth (90, 130, 200, and 350 cm below ground surface). All depths were oxic to suboxic, except 200 cm, where the products of iron and sulfate reduction were observed concomitant with an increase in dissolved and/or colloidal OM, pH, alkalinity, and conductivity. We investigated the composition...

Negative Schottky Barriers and Spin-Polarized Fermi Crossings at WSe2/NbSe2 Interfaces

Thu, 23 Apr 2026 00:00:00 +0000

Discovering and engineering spin-polarized surface states in the electronic structures of condensed matter systems is a crucial first step in the development of spintronic devices, wherein spin-polarized bands crossing the Fermi level can facilitate information transfer. Here, through nanofocused angle-resolved photoemission spectroscopy (nano-ARPES) and density functional theory-based calculations, we show that the interface between monolayer WSe₂ and metallic NbSe₂ exhibits a negative Schottky barrier height of ∼ -30 meV: the K-point valleys of the semiconducting layer are shifted by ∼800 meV to produce a surface-localized Fermi surface populated only by spin-polarized charge carriers. By increasing the WSe₂ thickness, the Fermi pockets can be moved from K to Γ, demonstrating tunability of novel semimetallic phases that exist atop a substrate additionally possessing charge density wave and superconducting phases. Together, this study provides...

Harmonic suppression gratings for soft X-ray monochromators.

Thu, 23 Apr 2026 00:00:00 +0000

We describe an approach to harmonic suppression in soft X-ray monochromators by engineering the reflection grating's diffraction pattern to approximate a sinusoidal amplitude. At synchrotron and free-electron laser sources, X-ray beamlines powered by insertion devices produce a spectrum containing harmonic photon energies that can couple unwanted light into experiments. Beamlines in the soft X-ray energy range (100 eV to 2 keV) commonly employ energy-filtering elements to suppress these harmonics. Available approaches tend to be inefficient, significantly reducing the transmitted power. We show that with pseudo-grayscale binary halftone patterns, gratings can approximate a sinusoidal amplitude and suppress higher diffraction orders. Prototype demonstrations of lithographically fabricated gratings were conducted on a soft X-ray beamline with photon energies of 110 eV and 330 eV. Relative to a square-wave amplitude grating, the third-harmonic intensity was reduced by a factor of...

The Evolution of Magnetism in a Thin Film Pyrochlore Ferromagnetic Insulator

Thu, 23 Apr 2026 00:00:00 +0000

ABSTRACT The pyrochlore vanadates are compelling candidates for next‐generation dissipationless devices. and are ferromagnetic insulators ( T 70 K) that are believed to exhibit the magnon Hall effect and are expected to host topological magnons. Their completely dissipationless magnon edge states could be harnessed to realize low‐power information transport in spintronic or magnonic devices. As a crucial step in the realization of devices, we synthesize the first thin films of pyrochlore on isostructural substrates and explore the evolution of their magnetic properties down to the ultrathin limit. All films are insulating ferromagnets with transition temperatures of up to the bulk value ( T 68 K) that decrease with thickness according to finite‐size effects. Our films also exhibit a change in anisotropy from in‐plane to out‐of‐plane easy axis coincident with the development of partial strain relaxation and nonzero magnetic hysteresis in an applied field. This evolution demonstrates...

Oligoether-Functionalized PEDOT: Combining an EDOT Backbone with Polar Side Chains for Solution Processability and High Electrical Conductivity

Thu, 23 Apr 2026 00:00:00 +0000

Conjugated polymers functionalized with oligoether (OE)-based side chains are a key class of materials for various organic electronic applications, including transparent electrodes, thermoelectrics, electrochromic displays, and electrochemical transistors. Herein, we report a highly soluble OE-functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) homopolymer, prepared by direct (hetero)arylation polymerization, which allows solution processing to yield films with comparable redox properties to oxidatively polymerized PEDOT. This polymer, PEDOT(OE3), when optimally oxidatively doped, reaches among the highest electrical conductivities of any OE-functionalized polymer and is comparable to more synthetically complex OE-functionalized polymers. X-ray scattering and spectroscopy were utilized to rationalize the transport properties resulting from varying the doping level. Comparison of PEDOT(OE3) to a series of OE-functionalized dioxythiophenes with varying amounts of 3,4-ethylenedioxythiophene...

Dichotomy of flat bands in the van der Waals ferromagnet Fe5GeTe2

Wed, 22 Apr 2026 00:00:00 +0000

Quantum materials with bands of narrow bandwidth near the Fermi level represent a promising platform for exploring a diverse range of fascinating physical phenomena, as the high density of states within the small energy window often enables the emergence of many-body physics. On one hand, flat bands can arise from strong Coulomb interactions that localize atomic orbitals. On the other hand, quantum destructive interference can quench the electronic kinetic energy. Although both have a narrow bandwidth, the two types of flat bands should exhibit very distinct spectral properties arising from their distinctive origins. So far, the two types of flat bands have only been realized in very different material settings and chemical environments, preventing a direct comparison. Here we report the observation of the two types of flat bands within the same material system—an above-room-temperature van der Waals ferromagnet, Fe5−xGeTe2, distinguishable by a switchable iron site order. The...

Theoretical framework for soft X‐ray Fourier transform spectroscopy using the Wigner function

Wed, 22 Apr 2026 00:00:00 +0000

This work presents a theoretical framework for the propagation of partially coherent Gaussian radiation in a modified Mach-Zehnder interferometer designed for Fourier transform spectroscopy (FTS) applications. Using the Wigner function formalism, we analytically propagate the radiation through the system and benchmark our approach by comparing the resulting interference pattern and interferogram with previous works in the diffraction limit. Our analysis reveals that the transverse coherence length requirement of the incident light field for detectable modulation is less stringent than previously assumed. Additionally, we provide theoretical demonstrations of FTS performance across various wavelengths using the proposed setup. These findings underscore the potential of this interferometer to achieve high-resolution FTS in the soft X-ray regime.

Errors in reconstruction of dichroic X‐ray orientation tomography due to polarization rotation of the incident beam

Wed, 22 Apr 2026 00:00:00 +0000

Dichroic X-ray tomography is a technique in which the crystal orientation or magnetization of a sample is resolved in three dimensions. The best-known uses of this technique are for observation of magnetic moments via circular dichroism, using left- and right-handed circularly polarized X-ray beams. Another variant uses linear dichroism to resolve the crystal orientation. In both these techniques, it is assumed that the absorption of X-rays along a path inside a material can be computed as a line integral of a local absorption coefficient along the ray path. For linear dichroism, this assumption is inaccurate because the polarization of the beam changes along the propagation direction when the optic axis of the material is not aligned along the polarization. In this work, a finite-element Maxwell solver is used to simulate tomography and reconstructions. The propagation effect can lead to significant errors in the reconstructed orientations. These errors may be mitigated by taking...

Investigation of residue-specific radiation damage of peptides under different radiation doses, dose rates, and oxygen availability

Tue, 21 Apr 2026 00:00:00 +0000

Investigation of residue-specific radiation damage of peptides under different radiation doses, dose rates, and oxygen availability

Matrix polysaccharides affect preferred orientation of cellulose crystals in primary cell walls

Tue, 21 Apr 2026 00:00:00 +0000

The spatial organization and interactions of constituent components influence cell growth and determine physical and chemical properties of the cell wall, including its rigidity, flexibility, and degradability. Elucidating the interactions between cell wall polysaccharides is crucial for advancing our knowledge of how cell walls are assembled and for designing approaches to efficiently break down cell walls to produce renewable energy and biomaterials. Here, we investigated the effect of defects in the biosynthesis of cell wall components on the nanoscale organization of cellulose in primary cell walls through grazing incidence wide angle X-ray scattering (GIWAXS) measurements of hypocotyls of wild type Arabidopsis thaliana and of cellulose, pectin, and xyloglucan (hemicellulose) deficient mutants. GIWAXS reveals changes in lattice spacings, coherence lengths, and relative crystalline content for cellulose between wild type and mutant plants. In addition, X-ray pole figures constructed...

Electronic Band Structures of a Germanium Halide Perovskite Semiconductor

Tue, 21 Apr 2026 00:00:00 +0000

CsGeX3, a class of halide perovskites, is an emergent semiconductor with ferroelectricity and potential optoelectronic properties that can be harnessed for device applications. However, measurements of the electronic structure for this class of material are still lacking. In this work, we report, for the first time, the experimental band structures of CsGeI3, a ferroelectric halide perovskite semiconductor, through angle-resolved photoemission spectroscopy (ARPES). The crystals were cleaved along both the (110) and (111) surfaces, facilitating the observation of clear valence band dispersions in several high-symmetry momentum directions. The observed valence band is characterized by a small hole effective mass of ∼0.1m 0 at the valence band maximum, without notable spectral signatures associated with the Rashba effect. Our experimental measurements are supported by electronic structure calculations in the DFT + G0W0 framework, enabling assessment of the band orbital characteristics,...

Evidence for strong electronic correlations in the bulk state of grey arsenic

Tue, 21 Apr 2026 00:00:00 +0000

We investigate the electron band structure of grey arsenic, whose (111) face hosts the topological Shockley state. Interestingly, the bulk band close to the touching point with the surface state exhibits the characteristics of inelastic scattering. Moreover, the band structure analysis reveals linearity in the imaginary part of electron self-energy. These features are analogous to those observed in high-temperature superconductors and marginal Fermi liquid systems, respectively, where strong electronic correlations exist. Our results suggest that correlated many-body states can be connected by non-interacting topological states, providing a viable playground to explore the coupling between topological and correlated states via grey arsenic surface.

Toward Unified Autonomous Scattering Experiments: A Cross-Facility Case Study at ALS and PETRA III

Tue, 21 Apr 2026 00:00:00 +0000

Autonomous experiments rely on the integration of control, data acquisition, analysis, and decision-making frameworks. While such systems have been demonstrated at individual facilities, adapting them to additional instruments remains challenging due to differences in local infrastructure. We present a modular workflow that connects existing open-source tools for data access (Tiled), workflow orchestration (Prefect), analysis and visualization (pyFAI, Plotly Dash), and Gaussian-process-based adaptive sampling (gpCAM) into a unified framework for autonomous scattering experiments. The same configuration operates across two synchrotron beamlines (ALS 7.3.3 and PETRA III P03) with only minimal facility-specific adjustments, as shown in proof-of-concept demonstrations. This validates that a consistent design emphasizing modularity and shared interfaces can ease deployment across diverse experimental environments. The resulting framework provides a flexible foundation for extending...

Electrochemical dynamics of imidazolium ionic liquids at graphene electrodes for energy storage applications

Fri, 3 Apr 2026 00:00:00 +0000

Electric double layer capacitors (EDLCs) are prominent energy storage systems that constitute the foundation of more reliable and sustainable energy infrastructures. Modern EDLCs often incorporate ionic liquids (ILs) as a key component in their electrolytes, leveraging the high electrochemical stability of ILs to enhance device performance. The performance and functionality of these capacitors also hinge on the interfacial behavior of ILs at electrode surfaces, which remain insufficiently understood. Here, we performed synchrotron infrared nanospectroscopy (SINS) in combination with density functional theory (DFT) calculations to investigate the electric double layers (EDLs) of three imidazolium-based ILs in a custom-designed graphene liquid cell. This approach revealed new insights into the dynamics of IL EDLs and the underpinning factors originating from the IL structures. Variations in anion size and structure were found to tune the ILs’ ability to form EDLs with compact and...

Visualizing electronic structure of twisted bilayer MoTe2 in devices

Tue, 31 Mar 2026 00:00:00 +0000

The pursuit of emergent quantum phenomena lies at the forefront of modern condensed matter physics. A recent breakthrough in this arena is the discovery of the fractional quantum anomalous Hall effect (FQAHE) in twisted bilayer MoTe₂ (tbMoTe₂), marking a paradigm shift and establishing a versatile platform for exploring the intricate interplay among topology, magnetism, and electron correlations. While significant progress has been made through both optical and electrical transport measurements, direct experimental insights into the electronic structure – crucial for understanding and modeling this system – have remained elusive. Here, using spatially and angle-resolved photoemission spectroscopy (μ-ARPES), we directly map the electronic band structure of tbMoTe₂. We identify the valence band maximum, whose partial filling underlies the FQAHE, at the K points, situated approximately 150 meV above the Γ valley. By fine-tuning the doping level via in-situ alkali metal deposition,...

Revealing Local Structures through Machine-Learning-Fused Multimodal Spectroscopy

Tue, 31 Mar 2026 00:00:00 +0000

Atomistic structures of materials offer valuable insights into their functionality. Determining these structures remains a fundamental challenge in materials science, especially for systems with defects. While both experimental and computational methods exist, each has limitations in resolving nanoscale structures. Core-level spectroscopies, such as X-ray absorption (XAS) or electron energy-loss spectroscopies (EELS), have been used to determine the local bonding environment and structure of materials. Recently, machine learning (ML) methods have been applied to extract structural and bonding information from XAS/EELS data. However, frameworks relying solely on a single data stream, defined as characterization data derived from a single element using one technique, are often insufficient because multiple local environments can yield similar spectral features, making it challenging to differentiate between competing structural hypotheses. In this work, we address this challenge...

Investigating the electrical transport properties and electronic structure of Zr2CuSb3

Tue, 31 Mar 2026 00:00:00 +0000

The checkerboard lattice has been proposed to host topological flat bands as a result of destructive interference among its various electronic hopping terms. However, it has proven challenging to realize experimentally due to the difficulty of isolating this structure from any significant out-of-plane bonding while maintaining structural integrity. Here, single crystals of Zr2CuSb3, a potential candidate for the checkerboard lattice, were synthesized using the solution (self-flux) method, and their structure was confirmed via x-ray diffraction. Electrical-transport measurements indicate metallic behavior with electron-dominated carriers. Angle-resolved photoemission spectroscopy reveals multiple electron pockets and significant kz broadening due to its large c axis and low dispersion features in kz. Density-functional theory (DFT) calculations further disentangle the contributions from each high-symmetry plane, providing a comprehensive characterization of electronic behavior....

Absence of magnetic order in epitaxial RuO2 revealed by x-ray linear dichroism

Tue, 31 Mar 2026 00:00:00 +0000

Recently the topic of altermagnetism has attracted tremendous attention, and RuO2 has been demonstrated to be one of the most promising altermagnetic candidates. However, disputes still remain on the existence of magnetic order in RuO2. Here in this work, we employ x-ray linear dichroism (XLD), a widely utilized technique for characterizing antiferromagnets, in conjunction with photoemission electron microscopy and multiple scattering calculation to provide clear evidence of the absence of magnetic order in epitaxial RuO2 films. The observed XLD signal is nearly invariant with temperature and independent of cooling-field direction, in stark contrast to the substantial magnetic-order-related XLD signal predicted by multiple scattering calculation. This finding strongly suggests a nonmagnetic origin for RuO2. Furthermore, we observed significantly distinct XLD signals at the Ru M3 and O K edges in RuO2 films grown on TiO2 substrate with different surface orientations, which can...

Absence of detectable spin and orbital pumping from Ni to Nb by out-of-plane ferromagnetic resonance

Tue, 31 Mar 2026 00:00:00 +0000

Excited ferromagnets can pump spin angular momentum, along with possibly orbital angular momentum. Among elemental ferromagnets, Ni has been proposed to exhibit substantial orbital pumping relative to spin pumping. Here, we search for a signature of orbital pumping by Ni, specifically by comparing out-of-plane ferromagnetic resonance in heterostructures without Ni (FeV/Nb) and with Ni (FeV-Ni/Nb). The FeV/Nb series shows a clear increase in Gilbert damping with the Nb sink thickness, attributed to spin pumping from FeV to Nb. Surprisingly, the FeV-Ni/Nb series exhibits no such damping increase, revealing no significant spin or orbital pumping from Ni to Nb. Our results offer a fresh perspective on angular-momentum transfer in Ni/Nb heterostructures.

Microstructure of amide-functionalized polyethylenes determined by NMR relaxometry

Tue, 31 Mar 2026 00:00:00 +0000

Amidation of polyethylenes creates a range of amide-containing materials with enhanced properties, but the effect of these functional groups on the microstructure of these new materials is not known. Here we employ solid-state nuclear magnetic resonance (NMR) techniques to analyze the microstructure of amide-modified polyethylenes. While a decrease in crystallinity was observed with increasing amounts of functionalization, we found by measuring the chain mobility of the crystalline, amorphous, and interphasial regions of the polyethylenes with NMR relaxation techniques that the grafted amidyl groups partition into the rigid amorphous fraction (RAF) between the crystalline and amorphous regions. The chemical specificity of these NMR experiments creates precise assessments of the location of functional groups within the materials. Together, these insights into the microstructure and morphology of amide-containing polyethylenes lay a foundation for a deeper understanding of the structure...

Topochemical Oxidation of Ruddlesden–Popper Nickelates Reveals Distinct Structural Family: Oxygen-Intercalated Layered Perovskites

Tue, 31 Mar 2026 00:00:00 +0000

Layered perovskites─including the Dion-Jacobson, Ruddlesden-Popper, and Aurivillius families─exhibit a wide range of correlated electron phenomena, from high-temperature superconductivity to multiferroicity. Here, we report a new family of layered perovskites realized through topochemical oxidation of La_n+1Ni_nO_3n+1+δ (n = 1-4) Ruddlesden-Popper nickelate thin films. Postgrowth ozone annealing induces a substantial c-axis expansion─17.8% for La₂NiO_4+δ (n = 1)─that monotonically decreases with increasing n. Surface synchrotron X-ray diffraction and coherent Bragg rod analysis (COBRA) reveal that this structural expansion arises from the intercalation of approximately δ ≈ 0.7-1.0 oxygen atoms into interstitial sites within the rock salt spacer layers, far exceeding the previous record of δ ≈ 0.3 for any Ruddlesden-Popper oxide. These oxygen-intercalated phases form a new class...

Binary pseudo-random array standard for extreme ultraviolet lithography tool characterization

Wed, 25 Mar 2026 00:00:00 +0000

Extreme ultraviolet (EUV) imaging tools play a crucial role in EUV lithography. Achieving high accuracy in EUV metrology is essential for advanced semiconductor manufacturing. A thorough characterization of the instrumentation in use is required. Binary pseudo-random arrays (BPRAs) are an established standard for calibrating and characterizing optical instruments in the frequency domain. We expand the BPRA standard to applications in EUV imaging. To extend the technology to the EUV spectral range, a high-resolution BPRA target with the smallest feature size of 40 nm is developed. The EUV BPRA target establishes an in situ and portable calibration and alignment standard for EUV imaging. The target is patterned by means of electron-beam lithography, using a nickel absorber with a thickness of 39 nm. The substrate is a 4″ silicon wafer with a molybdenum/silicon multilayer coating. To demonstrate the efficacy of the target and develop the instrument calibration protocol, the target...

A comparative study on cubic and tetragonal Ce-ZrO2 supported Rh catalysts for N2O decomposition

Tue, 24 Mar 2026 00:00:00 +0000

Zirconium oxide (ZrO2) exhibits strong synergy with cerium oxide (CeO2), acting as a structural and electronic promoter during catalytic redox reactions. As a result, Ce-ZrO2 composite oxides are widely used as supports in various catalytic systems. In our previous work, we demonstrated that the incorporation of Zr4+ into the CeO2 lattice significantly enhanced Rh dispersion, improved redox ability, and stabilized surface Rh species, which collectively boosted the de-N2O activity of Rh/Ce-ZrO2 catalysts. Building on these findings, the present study emphasizes that the crystallographic phase of Ce-ZrO2, governed by the Ce/Zr ratio, plays a decisive role in tuning the physicochemical environment of Rh active sites and thereby optimizing catalytic performance. Tailoring the Ce/Zr ratio to favor the cubic fluorite structure emerges as a promising strategy for the rational design of highly active and stable catalysts for N2O decomposition and potentially other redox-sensitive environmental...

Elasticity of davemaoite as a primary contributor to lower-mantle heterogeneities

Mon, 23 Mar 2026 00:00:00 +0000

Geophysical detection of subducted mid-ocean ridge basalt (MORB) in the lower mantle is hindered by uncertainties in the elasticity of Fe,Al,Mg,Ti-bearing davemaoite, a key MORB component. Using Brillouin spectroscopy and x-ray diffraction, we determined the elasticity of a Ca_0.906(1)Fe²⁺_0.027(1)Fe³⁺_0.042(1)Mg_0.033(1)Al_0.072(1)Ti_0.020(1)Si_0.912(1)O₃ davemaoite up to 113 gigapascals and 2294 K. We found that it exhibited a shear wave velocity 10 to 20% slower than end-member davemaoite, making it the slowest phase among major lower-mantle minerals. Our models show that MORB, containing 20 to 25 volume percent davemaoite, potentially contributes to large low-shear-velocity provinces (LLSVPs), whereas a cumulate layer enriched in davemaoite crystallized from basal magma ocean may comprise ultralow-velocity zones (ULVZs). Davemaoite's ability to host incompatible and heat-producing...

Polaronic Quasiparticles in the Valence-Transition Compound TmSe1-xTex

Mon, 23 Mar 2026 00:00:00 +0000

Exotic quasiparticle states have been proposed in mixed-valent compounds exhibiting valence transitions. However, clear spectroscopic evidence identifying these states has remained elusive. Using synchrotron-based hard x-ray and extreme ultraviolet photoemission spectroscopy, we have probed the Tm 3d and 4f emissions in TmSe_{1-x}Te_{x}, where a Te concentration-dependent semimetal-insulator transition occurs alongside the valence transition. Our photoemission results, which are characteristic of the bulk, track this combined transition across the critical concentration (x_{c}=0.29). Notably, our results reveal a noninteger valence for the insulating phase and a novel quasiparticle excitation in the semimetallic phase: a Holstein polaron that extends beyond the standard periodic Anderson model.

Effect of Stoichiometry on the Structure and Polarization of BaTiO3

Fri, 20 Mar 2026 00:00:00 +0000

Abstract Barium titanate (BaTiO 3 ) is a material of interest for photonic device applications due to its strong optical non‐linearity. However, BaTiO 3 ‐based devices have not found widespread adoption, in part due to the challenges associated with synthesizing high quality thin‐films. Here, high‐resolution scanning transmission electron microscope (STEM) imaging is used to investigate the atomic structure of both on‐ and off‐stoichiometric BaTiO 3 synthesized by molecular beam epitaxy (MBE). This investigation reveals an asymmetry in the way the BaTiO 3 atomic lattice accommodates off‐stoichiometry growth and unveils features beyond what is expected from diffraction or surface characterization techniques. Excess titanium incorporates into the BaTiO 3 lattice to form pervasive defects despite titanium‐rich films having a low surface roughness and high‐quality appearance in diffraction. Excess barium forms a rough, water‐soluble surface layer but does not...

Random heteropolymers as enzyme mimics

Thu, 19 Mar 2026 00:00:00 +0000

Despite successes in replicating the primary–secondary–tertiary structure hierarchy of protein, it remains elusive to synthetically materialize protein functions that are deeply rooted in their chemical, structural and dynamic heterogeneities1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11–12. We propose that for polymers with backbone chemistries different from that of proteins, programming spatial and temporal projections of sidechains at the segmental level can be effective in replicating protein behaviours13,14; and leveraging the rotational freedom of polymer can mitigate deficiencies in monomeric sequence specificity and achieve behaviour uniformity at the ensemble level2,3,15, 16, 17, 18, 19–20. Here, guided by the active site analysis of about 1,300 metalloproteins, we design random heteropolymers (RHPs) as enzyme mimics based on one-pot synthesis. We introduce key monomers as the equivalents of the functional residues of protein and statistically modulate the chemical characteristics...

Machine Learning Framework for Characterizing Processing–Structure Relationship in Block Copolymer Thin Films

Thu, 19 Mar 2026 00:00:00 +0000

The morphology of block copolymers (BCPs) critically influences material properties and applications. This work introduces a machine learning (ML)-enabled, high-throughput framework for analyzing grazing incidence small-angle X-ray scattering (GISAXS) data and atomic force microscopy (AFM) images to characterize BCP thin film morphology. A convolutional neural network was trained to classify AFM images by surface features, achieving 97% testing accuracy. Classified images were then analyzed to extract 2D grain size measurements from the samples in a high-throughput manner. ML models were trained to predict domain orientation based on processing parameters such as solvent ratio, additive type, and additive ratio. GISAXS-based properties were predicted with strong performances (R ² > 0.75), while AFM-based property predictions were less accurate (R ² < 0.60), likely due to the localized nature of AFM measurements compared to the bulk information...

Resolving the Valence of Iron Oxides by Resonant Photoemission Spectroscopy

Mon, 16 Mar 2026 00:00:00 +0000

Precisely determining the oxidation states of metal cations within variable-valence transition metal oxides remains a significant challenge, yet it is crucial for understanding and predicting the properties of these technologically important materials. Iron oxides, in particular, exhibit a remarkable diversity of electronic structures due to the variable valence states of iron (Fe²⁺ and Fe³⁺). A quantitative analysis using conventional X-ray photoelectron spectroscopy (XPS) is challenging because of the strong overlap of the Fe 2p XPS peaks from different oxidation states. In this study, we show how this problem can be resolved using Resonant Photoemission Spectroscopy (ResPES), which unambiguously distinguishes Fe oxidation states and spectroscopically estimates the composition ratio of Fe cation valence states in the complex Fe oxides. We demonstrate this in the model case of a FeO₂ monolayer film on Pt(111), showing that the FeO₂...

SAN-Based Block Polymers as a Platform for Manufacturing Strong Isoporous Membranes

Mon, 16 Mar 2026 00:00:00 +0000

Ultrafiltration (UF) membranes are ubiquitous in water purification and bioprocessing. However, their mechanical and transport properties remain challenging to codesign because of the broad pore size distributions at the surface and within the bulk that result from nonsolvent-induced phase separation (NIPS)their typical manufacturing process. These distributions influence the hydrodynamic resistance to water flow and the stress concentrations around pores. Thus, developing advanced UF membranes requires innovative molecular designs that offer control over the surface and bulk pores, as well as the mechanical properties of the load-bearing polymer. We introduce a platform for manufacturing UF membranes by leveraging solution self-assembly of block polymers and chain architectures with pendant polar groups. The block polymers consist of a poly(styrene-co-acrylonitrile) hydrophobic block, which is known for its strength, and a poly(4-vinylpyridine) hydrophilic block, which drives...

Local structural distortions drive magnetic molecular field in compositionally complex spinel oxide

Fri, 13 Mar 2026 00:00:00 +0000

Understanding how local distortions determine the functional properties of high entropy materials, containing five or more elements at the same crystallographic site, is an open challenge. We address this for a compositionally complex spinel oxide (Mn0.2Co0.2Ni0.2Cu0.2Zn0.2)Cr2O4 (A5Cr2O4). By comparatively examining extended X-ray absorption fine structure on A5Cr2O4 and its parent counterparts, ACr2O4, along with density functional theory calculations for multiple configurations, we find that the element-specific distortions go beyond the first neighbor. Specifically, the strong Jahn-Teller distortion present in CuCr2O4 is found to be completely suppressed in A5Cr2O4 even locally. Instead, there is a broad distribution of Cu-O and Cu-Cr bond distances, while other A-O distances acquire certain specific values. This study demonstrates the additional flexibility of a cationic sublattice in maintaining a uniform long-range structure, in contrast to previous reports showing only...

Low-nickel cathode chemistry for sustainable and high-energy lithium-ion batteries

Thu, 12 Mar 2026 00:00:00 +0000

The transition to sustainable energy storage demands lithium-ion batteries with high energy density and reduced reliance on critical metals such as nickel (Ni), yet current strategies to increase capacity have largely depended on raising Ni content, leading to escalating supply risks, rising costs and sustainability concerns. More critically, Ni-rich cathodes suffer from rapid electrochemical degradation driven by structural instability, creating an insurmountable trade-off between capacity and cycle life. Here we introduce a low-Ni chemistry cathode, Li(Li0.05Ni0.57Mn0.31Co0.07)O2, with a radial phase integration design that overcomes these limitations, enabling a remarkable Ni usage reduction (Ni < 0.6) while demonstrating high capacity (215 mAh g−1) and markedly improved cyclability (~97% retention over 400 cycles) compared to conventional high-Ni cathodes (Ni = 0.8). Advanced X-ray and electron microscopy analyses reveal that the designed cathode exhibits a highly reversible...

Effect of cell compression on the performance and the structure of proton exchange membrane water electrolyzer (PEMWE) assembly

Thu, 12 Mar 2026 00:00:00 +0000

In the field of water electrolysis, the proton exchange membrane water electrolyzer (PEMWE) is currently the most advanced technology for producing hydrogen without emitting CO2. Although PEMWE plants are already in operation, further research is needed to improve cell efficiency and reduce the use of rare materials, such as iridium oxide catalysts for the oxygen evolution reaction (OER). One of the main causes of performance loss in PEMWE is the relatively low electric conductivity of the porous transport layer (PTL) and of the anode catalyst layer, which results in ohmic losses and low catalyst utilization during high current density operation. The objective of this study is to investigate how optimization of the PTL and electrode interface can increase the cell performance. To this end, we tested different cell assemblies using fibrous and sintered PTLs, decreasing membrane thickness, reducing iridium loading, and inserting a microporous layer to increase contact surface area....

Using X-ray radiography to study oxygen flow in a proton exchange membrane electrolyzer operating under balanced pressure conditions

Wed, 11 Mar 2026 00:00:00 +0000

Of the various water electrolyzer technologies, the proton exchange membrane electrolyzer (PEMWE) is one of the best solutions for producing clean hydrogen without releasing CO2. In order to allow for widespread use of clean hydrogen, it is necessary to decrease its cost, which is intrinsically related to system operation. Current PEMWE plants operate in differential mode, directly pressurizing hydrogen and benefiting from thermodynamic compression, which increases overall system efficiency. However, high differential pressure above 30 bar can cause membrane stress, resulting in membrane creeping and failure. Pressurizing the water and operating at balanced pressure allows hydrogen to be produced at higher pressures while preserving the integrity of the membrane and porous layers. Nevertheless, the impact of pressurizing water on PEMWE performance must be better understood to maximize performance under balanced pressure conditions. This study examined the impact of water...

Quantification of grain rotation in bulk nanostructured copper via in situ heating white beam synchrotron X-ray diffraction

Wed, 11 Mar 2026 00:00:00 +0000

Grain rotation during microstructural relaxation under heating is conventionally studied extensively through transmission electron microscopy and simulations. However, there is a shortage in examining grain rotations at larger length and volume scales in bulk materials. It is critical to understand the thermal stability of bulk nanostructured metals, since those enhanced mechanical properties have been well recognized. This study aimed to employ a white beam microdiffraction X-ray technique under in situ heating from 300 K to 1073 K at 12 K/min on a nanostructured copper processed by high-pressure torsion, yielding an initial grain size of ∼260 nm before the heating. Evaluation across a wide range of temperatures reveals transition temperatures associated with microstructural relaxation processes. By tracking separate Laue diffraction peaks stemming from individual grains, changes in their orientations can be estimated and quantified. This approach becomes particularly effective...

Pd-promoted reduction and restructuring of an In2O3-based catalyst for CO2 hydrogenation at room temperature

Fri, 6 Mar 2026 00:00:00 +0000

An unconventional reaction mechanism in an In2O3/Pd(111) inverse model catalyst for the CO2 hydrogenation reaction has been uncovered: In2O3 is partially reduced at room temperature in a reaction atmosphere as a result of its direct contact with Pd(111), which is an efficient H2 splitter. The reduction induces changes in surface free energy, leading to a dynamical restructuring at the In2O3/Pd(111) interface via formation of InOx and outward diffusion of Pd, as revealed by ambient pressure X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and density functional theory simulations. This dynamical restructuring eventually promotes the growth of 2D InPdyOx nanodomains as the catalytically active phase and the exclusive formation of methanol upon hydrogenation of CO2 at room temperature. A comparable high selectivity toward CH3OH was found in more realistic bulk catalytic systems (2 wt% Pd/In2O3 catalyst and commercial CZA catalyst). Scanning tunneling microscopy...

Ammonia Synthesis under Ambient Conditions: Insights into Water–Nitrogen–Magnetite Interfaces

Fri, 6 Mar 2026 00:00:00 +0000

New routes for transforming nitrogen into ammonia at ambient conditions would be a milestone toward an energy efficient and economically attractive production route in comparison to the traditional Haber-Bosch process. Recently, the synthesis of ammonia from water and nitrogen at room temperature and atmospheric pressure has been reported to be catalyzed by Fe₃O₄ at the air-water interface. By integrating ambient pressure X-ray photoelectron spectroscopy and ab initio molecular dynamics and free energy calculations, we investigate the underlying thermodynamic mechanisms governing ammonia and hydrazine formation at the water-Fe₃O₄-nanoparticle interface. We find that, unlike pure Fe₃O₄ where N₂ can only interact with a limited number of Fe sites, hydroxylated species introduce large and diverse adsorption geometries where N₂ can bind through either Fe sites or Fe-OH groups, each of which are...

Probing the Surface Chemistry of Lithium Nitridation

Fri, 6 Mar 2026 00:00:00 +0000

Chemical synthesis of Li₃N through lithium nitridation has potential to advance rechargeable battery and nitrogen fixation technology. However, studies of the conditions for forming Li₃N on the lithium surface via nitrogen gas exposure report contradictory findings, such as the spontaneous reaction of Li with pure N₂, the impossibility of forming Li₃N through pure Li and N₂ interaction, the requirement of trace H₂O to catalyze the reaction, and evidence to the contrary. In this study, ambient pressure X-ray photoelectron spectroscopy (APXPS) was applied to evaluate the in situ chemical evolution of the lithium metal surface under nitrogen gas up to 800 mTorr. At pressures ≤10 mTorr, no Li₃N was detected. At higher pressures, surface Li₃N rapidly reacts with trace CO₂. Additionally, because metallic lithium is readily oxidized by trace gases, the atomic nitrogen concentration of the...

Chemical Composition and Mixing State of Wintertime Aerosol from the European Arctic Site of Ny-Ålesund, Svalbard

Fri, 6 Mar 2026 00:00:00 +0000

The Arctic is rapidly warming, and aerosols play an increasingly important role by scattering and absorbing sunlight and by participating in cloud formation. Their optical and cloud-forming properties depend on the mixing state and chemical composition, but observations of these features remain limited. This study comprehensively characterizes 25,254 individual particles collected at Ny-Ålesund, Svalbard (November −December 2020), using microspectroscopy techniques to investigate their size, morphology, mixing state, and chemical composition. Fresh sea salt aerosols (SSA) were identified as the most abundant (∼85%), of the total observed aerosol population, with potential sources from sea spray and blowing snow. Air masses originating from the Arctic Ocean surrounding Svalbard likely contribute to increased concentrations of sub-micrometer “Fresh SSA” particles. “Aged SSA” particles (7.4%) are enriched in sulfur and nitrogen, compared to “Fresh SSA”. These elevated ratios may...

Pt Particles on a Dynamic TiO2 Support in Near-Ambient Conditions–Disentangling Size, Pressure, and Support Effects

Fri, 6 Mar 2026 00:00:00 +0000

Platinum particles on reducible oxides are known to form complex and highly dynamic catalyst systems at elevated pressures and temperatures, often adopting active structures that differ from those found at room temperature and under ultrahigh vacuum (UHV). Here, we study the oxidation and structural evolution of subnanometer Pt clusters and nanoparticles supported on rutile TiO₂(110) across an oxygen pressure range from UHV to 0.1 mbar, using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), scanning tunneling microscopy (STM) under UHV and NAP conditions, and low-energy ion scattering (LEIS). Our results reveal distinct differences in oxidation behavior and thermal stability between Pt nanoparticles and clusters, which are further modulated by the support stoichiometry and oxygen pressure. Small Pt clusters become oxidized even at room temperature but are susceptible to accelerated sintering in 0.1 mbar O₂ at elevated temperatures. In contrast,...

Physicochemical and Molecular Insights into the Boundary Layer and Free Troposphere Aerosol Interactions over the Southern Great Plains

Fri, 6 Mar 2026 00:00:00 +0000

Ambient aerosol vertical profiles are critical for evaluating the role of aerosols in atmospheric chemistry and radiative transfer, but limited data on these profiles hinder our ability to fully assess their impact on the Earth's radiative balance. Here, we investigated the size-, time-, and altitude-resolved composition of individual particles and the bulk molecular composition of particle samples collected by an uncrewed aerial system─ArcticShark over the Southern Great Plains. Single-particle microanalysis shows that the free tropospheric (FT) samples are dominated (56-66%) by carbonaceous sulfate particles, while boundary layer (BL) samples are dominated (57-74%) by carbonaceous particles. Back-trajectory simulations suggest that FT particles are likely influenced by long-range transport and have undergone aqueous-phase processing. Conversely, in situ size distribution data show evidence of particle growth in the upper BL and just below the FT. This observation may indicate...

Multiscale Mechanisms of Twisted Carbon Nanotube Yarns Probed In Situ by Soft X‑rays during Tensile Loading

Fri, 6 Mar 2026 00:00:00 +0000

Piecing together carbon nanotubes (CNTs) into assemblies has so far failed to achieve the same elite strength performance metrics as individual CNTs, highlighting a critical deficiency in understanding the effects that the processing of individual nanostructures have on the performance of their derived macroscale assemblies, thereby hindering the development of a process-structure-performance map for these materials. In this work, we propose a method to decouple the distribution orientation of nanoscale tortuosity and the microscale twist of CNT dry-spun yarns under applied loads via in situ soft X-ray probing at high energy (1200 eV) and low energy (280 eV), respectively. With this decoupling enabled by in situ soft X-ray scattering, we acquired a deeper understanding of the deformation mechanisms of these yarns. We found that for untreated yarns, the twist angle of collective CNT bundles at the macroscale is more sensitive to applied stress than the nanoscale alignment...

Isolation of a Terminal Cobalt Nitride in a Metal–Organic Framework

Thu, 5 Mar 2026 00:00:00 +0000

Transition metal nitrides are reactive intermediates in biological and industrial processes. Chemists have synthesized molecular model complexes of such reactive species to understand their function and electronic requirements for new applications. However, molecular chemistry can suffer from intra- and intermolecular decomposition pathways, which preclude further discovery of unknown reactive species. Metal-organic frameworks offer an opportunity for creating long-lived forms of such species with the vacuum of the pore suppressing degradation while simultaneously enabling substrate access for controlled reactivity studies. Here, we report the characterization of an elusive terminal cobalt nitride species generated through photolysis or thermolysis of a site-isolated cobalt azide within the evacuated metal-organic framework CoN₃-MFU-4l. The first crystal structure of such a species is presented, with vibrational, X-ray absorption, and electron paramagnetic resonance...

Wildfire Produces Transient Minerals: Speciation, Reactivity, and Fate of Iron and Manganese in Surface Soils Post Wildfire

Thu, 5 Mar 2026 00:00:00 +0000

Wildfire leads to the deposition of an ash layer at the land surface. This material typically has alkaline properties, abundant pyrogenic carbon, and elevated metal concentrations compared to surface soils. Here, we compare ash and surface soils collected three weeks and two years after the Glass Fire (St. Helena, California, USA) to determine how wildfire affects the speciation and reactivity of iron (Fe) and manganese (Mn), two micronutrients that influence many soil processes. Synchrotron-based analyses revealed that wildfire generated stable Fe oxides like maghemite (γ-Fe₂O₃) and hematite (α-Fe₂O₃) that likely derived from surface soil or mineral dust rather than the vegetation, and Mn oxides such as hausmannite (Mn₃O₄) and bixbyite (Mn₂O₃) that derived primarily from aboveground biomass. However, these pyrogenic minerals were absent in soils collected two years after the fire. Their loss...

Selective semihydrogenation of acetylene in ethylene using defect-rich boron nitride catalyst from flux reconstruction

Tue, 3 Mar 2026 00:00:00 +0000

Efficient removal of trace acetylene from ethylene streams is essential for producing polymer-grade ethylene, yet achieving highly selective semihydrogenation without over-hydrogenation remains a long-standing challenge. A key barrier is the lack of a simple, low-cost catalyst that can activate hydrogen effectively while preventing ethylene from reacting further. Here we show that defect-rich boron nitride, prepared through a straightforward flux reconstruction method, serves as a highly selective and metal-free catalyst for acetylene semihydrogenation. The catalyst contains abundant open boron and nitrogen sites that enable efficient hydrogen activation and rapid release of ethylene, thereby avoiding over-hydrogenation. Experiments combined with isotope labeling and theoretical analysis reveal that these defects lower the energy barrier for hydrogen activation while accelerating product desorption. Our findings demonstrate a scalable strategy for defect engineering in boron nitride...

Multi-element tomography: leveraging absorption and phase contrast in soft x-ray ptychography

Fri, 27 Feb 2026 00:00:00 +0000

X-ray ptychography enables high-resolution imaging of multi-element systems by providing both optical density and phase contrast images. This study integrates few-energy ptychography with computed tomography to distinguish and spatially resolve nickel nanoparticles within a porous Al₂O₃ support. By leveraging contrast differences near a given absorption edge, our method achieves unambiguous 3D identification of an element using a single energy, significantly reducing acquisition time while maintaining nanoscale resolution. This approach is particularly valuable for studying catalytic processes, such as nanoparticle exsolution and dissolution in mesoporous alumina. High-resolution 3D imaging of these structures advances our understanding of catalytic dynamics, with implications for optimizing materials in environmental applications like dry reforming methane.

Synthesis of phosphorus-containing HZSM-5 zeolite particles: Control of phosphorus incorporation through a hydrophobic external-surface Shell

Wed, 25 Feb 2026 00:00:00 +0000

Selective blocking of external surface HZSM-5 zeolite (Si/Al of 11.5) silanol sites followed by impregnating the zeolite with phosphate leads to changes in the zeolite acidity and catalytic performance for n-butane cracking. A monolayer of organosilane capping the zeolite external surface by chemisorption of 3-cyanopropyldimethylchlorosilane formed a hydrophobic shell consisting of 0.36 cyano groups/nm2. Partial hydrolysis of the shell by wetting of the zeolite by water allowed tuning of the transport/chemical reaction tradeoff during aqueous impregnation of the zeolite with phosphate, facilitating efficient distribution of the phosphorus in the internal pore space. The procedure led to a higher degree of framework aluminum retention and a higher total Brønsted acid-site density than was observed with phosphorus-modified HZSM-5 prepared by conventional aqueous wet impregnation. Correspondingly, the phosphorus-modified catalyst had a higher activity for n-butane cracking than the...

Multielectron Bond Cleavage Processes Enabled by Redox-Responsive Phosphinimide Ligands

Tue, 24 Feb 2026 00:00:00 +0000

The activation of small molecules via multielectron redox processes offers promise in mediating difficult transformations related to energy conversion processes. While molecular systems that engage in one- and two-electron redox processes are widespread, those that participate in the direct transfer of four or more electrons to small molecules are very rare. To that end, we report a mononuclear Cr^II complex competent for the 4-electron reduction of dioxygen (O₂) and nitrosoarenes. These systems additionally engage in facile two-electron group transfer reactivity, including O atom excision and nitrene transfer. Structural, spectroscopic, and computational studies support bond activation processes that intimately occur at a mononuclear chromium(phosphinimide) center and highlight the unusual structural responsiveness of the phosphinimides in stabilizing a range of metal redox states.

Accurate informatic modeling of tooth enamel pellicle interactions by training substitution matrices with Mat4Pep

Tue, 24 Feb 2026 00:00:00 +0000

Extracellular matrices direct the formation of mineral constituents into self-assembled mineralized tissues. We investigate the protein and mineral constituents to better understand the underlying mechanisms that lead to mineralized tissue formation. Specifically, we study the protein-hydroxyapatite interactions that govern the development and homeostasis of teeth and bone in the oral cavity. Characterization would enable improvements in the design of peptides to regenerate mineralized tissues and control attachments such as ligaments and dental plaque. Progress has been limited because no available methods produce robust data for assessing organic-mineral interfaces. We show that tooth enamel pellicle peptides contain subtle sequence similarities that encode hydroxyapatite binding mechanisms by segregating pellicle peptides from control sequences using our previously developed substitution matrix-based peptide comparison protocol with improvements. Sampling diverse matrices,...

Polarization Control via Artificial Optical Nonlinearity in Dielectric Metasurfaces

Tue, 17 Feb 2026 00:00:00 +0000

Nonlinear optical phenomena are generally governed by geometry in matter systems, as they depend on the spatial arrangement of atoms within materials or molecules. Metasurfaces, through precisely designed geometries on a subwavelength scale, allow the optical response of a material to be tailored far beyond its natural properties. Therefore, metasurfaces are highly appealing for enabling the engineering of nonlinear optical interactions. Current studies of nonlinear metasurfaces predominantly focus on the phase control of the generated light. Nonetheless, investigating the tensorial nature of the nonlinearity of metasurfaces and its effect on the polarization of the generated light is critical to fully unlocking a range of applications, such as nonlinear vector beam generation and nonlinear polarization imaging. Here, we study the artificial optical nonlinearity of a dielectric metasurface originating from its meta-atom symmetry and describe the third-order nonlinear behavior...

Spin-Valley Locking in 2H‑TaS2 and Its Co-Intercalated Counterpart: Roles of Surface Domains and Co Intercalation

Tue, 17 Feb 2026 00:00:00 +0000

Tuning and probing spin-valley coupling is key to understanding correlated ground states in 2H-TaS₂. Its magnetically intercalated analogue, Co_1/3TaS₂, introduces additional degrees of freedom, including modified interlayer coupling and magnetism, to modulate spin-valley physics. Surface-sensitive probes like ARPES are essential for accessing surface spin texture, yet previous studies on 2H-TMDs have reported conflicting results regarding spin-polarized bands, leaving open whether these discrepancies are intrinsic or extrinsic. Here we performed spatially resolved spin-ARPES measurements on 2H-TaS₂ and Co_1/3TaS₂. Our results reveal robust spin-valley locking on both compounds. Importantly, Co intercalation enhances interlayer hybridization and introduces magnetism while preserving the TaS₂-derived spin texture. We further observe a spatial reversal of the out-of-plane spin polarization,...

Persistent structural distortion for anticipated improper ferroelectricity in ultrathin h-Lu1−xCaxMnO3 films

Tue, 17 Feb 2026 00:00:00 +0000

Improper ferroelectricity in hexagonal rare-earth manganites (h-RMnO₃, R = Ho-Lu, Y, Sc) arises from a geometric distortion as the primary order parameter, resilient to depolarizing fields and promising for ultrathin ferroelectric devices. However, the substrate-induced interface clamping effect, which suppresses the geometric distortion in the sub-nanometer regime, has thus far hindered the realization of two-dimensional improper ferroelectrics. This study demonstrates that doping with calcium can enhance ferroelectric structural distortion in h-LuMnO₃thin films. Compressively strained h-Lu_1-xCa_xMnO₃(x= 0.1, 0.2, 0.3, 0.4, 0.5) epitaxial thin films were stabilized on sapphire substrates using an h-ScFeO₃buffer layer. We have found that the interface clamping effect is entirely overcome when the doping concentration reachesx⩾ 0.2, establishing a potential quasi-2D ferroelectric system with a remarkably...

Replication of x-ray blazed gratings by nano-inscribing

Tue, 17 Feb 2026 00:00:00 +0000

A nano-inscribing technique was tested as a method of cost-effective replication of blazed diffraction gratings for x-rays. A saw-tooth mold for the nano-inscribing was fabricated by a double-replication process from a master blazed grating. The nano-inscribing was performed using a UV-curable resist of low viscosity to provide a small thickness of the resist replicas, required for a following transfer process. The nano-inscribing process was optimized to minimize surface relaxation and preserve the saw-tooth shape of the grooves, required for high diffraction efficiency. The quality of the replica gratings was evaluated via diffraction efficiency simulations. The simulations demonstrated that near theoretical efficiency can be achieved for the x-ray gratings made by the nano-inscribing approach.

Emergence of Coordination-Mediated Electronic States in Disordered Ni-Polyphenyl Architectures