Dense plasma environment affects the electronic structure of ions via variations of the microscopic electrical fields, also known as plasma screening. This effect can be either estimated by simplified analytical models, or by computationally expensive and to date unverified numerical calculations. We have experimentally quantified plasma screening from the energy shifts of the bound-bound transitions in matter driven by the x-ray free electron laser (XFEL). This was enabled by identification of detailed electronic configurations of the observed K{\alpha}, K\b{eta} and K{\gamma} lines. This work paves the way for improving plasma screening models including connected effects like ionization potential depression and continuum lowering, which will advance the understanding of atomic physics in Warm Dense Matter regime.

X-ray absorption near-edge structure (XANES) spectroscopy is key to understanding functional materials. We present, to our knowledge, the first use of hard x-ray near-field holography (NFH) for three-dimensional (3D), spatially resolved XANES. While NFH provides lensless imaging with an adjustable field of view, it entails complex reconstruction. Our method jointly reconstructs NFH data acquired at multiple energies and enforces a low-dimensional spectral model based on the physically motivated assumption that each voxel spectrum is a linear combination of a small number of constituents. We demonstrate the approach on a mixed metal oxide catalyst particle, achieving accurate spectral reconstruction and revealing 3D chemical heterogeneity. XANES in NFH mode has the potential to enable nano-scale in-operando XANES microscopy with a large field of view.

Clay-based 3D printing has emerged as a low-carbon alternative to cementitious additive manufacturing in construction. However, pore space, inhomogeneities, shrinkage, and crack formation in clay-sand-water mixtures are still poorly understood, particularly with respect to their influence on the structural integrity of clay-printed elements. This paper investigates the use of X-ray computed tomography (CT) for specimen-scale analysis of clay-sand-water mixtures used in additive manufacturing. One printed specimen and two manually prepared reference specimens in the wet and dried state were scanned with the ENCI CT system. The reconstructed and segmented volumes were used to quantify pore volume, equivalent spherical diameter, sphericity, a derived specific pore surface, and spatial porosity distribution. The printed sample exhibited markedly smaller pores than the manually prepared dried sample, indicating compaction during extrusion and layer deposition, while the dried sample showed larger and more crack-like pores consistent with shrinkage during drying. Local porosity maps and their coefficients of variation were further used to identify heterogeneous zones that may act as mechanically weaker regions. The results demonstrate the feasibility of CT-based assessment for characterizing internal porosity and heterogeneity in 3D-printed clay elements.

Hundreds of cuneiform clay tablets unearthed in South-western Asia remain sealed within clay envelopes, leaving their texts inaccessible to Assyriologists. Computed tomography (CT) enables looking inside the clay envelopes non-destructively. An interdisciplinary team developed a transportable high-definition CT scanner named by ENCI, designed for on-site use in museums and archives. ENCI allows researchers to visualise the cuneiform text written on hidden tablets, study clay inclusions, and analyse manufacturing techniques without opening the tablets. First deployed at the Louvre Museum in Paris in 2024, it was later used at the Museum of Anatolian Civilisations in Ankara to scan around fifty encased tablets, many of them letters. Combined with advanced 3D surface extraction and visualisation software, ENCI enables virtual unwrapping and detailed exploration of small objects. This technology opens new possibilities for studying cultural heritage artefacts on site, while also revealing mineral and organic inclusions and evidence of envelope formation methods.

Scanning an X-ray nanobeam instead of the sample can be highly advantageous in experimental scenarios where a fast sample movement is not possible, such as in-situ measurements. Here, fast sample scanning is often hampered by a heavy or bulky sample environment. In this contribution, we present first results of an X-ray beam scanning experiment using a multilayer X-ray mirror to deflect a nanofocused X-ray beam created by diamond compound refractive lenses. By slightly tilting this mirror within the angular acceptance range of the multilayer, a nanofocused X-ray beam was scanned in horizontal direction by 28 mu m in the focal plane of the optics. This tilting is driven by an underlying biaxial micro-electromechanical system (MEMS) that can be rapidly steered. The performance of this X-ray MEMS mirror and its influence on the focusing properties of the X-ray beam will be presented.

In-situ imaging of chemical reactions can provide valuable insight into nanoparticle growth and structural evolution. Hard X-ray imaging is an excellent tool for this purpose, as it combines high spatial resolution with high penetration depth, allowing for realistic reaction environments. While far-field ptychography is a well-established method at synchrotron radiation sources, its near-field analog has received less attention. In this work we show that near-field multi-slice ptychography is a competitive method for high-resolution in-situ imaging by studying the formation of gold nanocages via galvanic replacement. Our work extends near-field X-ray ptychography to sub-50 nm spatial resolution by using multilayer Laue lenses. These high numerical aperture optics enable to distinguish sample layers that are separated by less than 100 µm by multi-slicing techniques.

Au bipyramids hosting body-centered orthorhombic and tetragonal lattices (bc(o,t)) exhibit extraordinary stability at ambient conditions and even under high-temperature/high-pressure conditions. The phases undergo conversion to a conventional face-centered cubic (fcc) lattice only during annealing at 700 °C due to the unlocking of the geometrically induced stresses. The spatial distribution of the phases in the crystallite volume has revealed fcc capped bc(o,t) lattices with two halves of the bipyramid twisted by ∼6° along the length with approximately ± 5% strain. Understanding the spatial distribution and dynamics of these phases at high temperatures can provide detailed information on their thermal stability. Herein, using nanoprobe scanning X-ray diffraction microscopy (SXDM), in situ annealing of the bc(o,t) Au bipyramid (∼1.5 μm long and 300 nm wide) has been performed at different temperatures (up to 800 °C). The study reveals untwisting of the domains assisted by the supplied high temperature, while the existing lattices undergo variation in parameters with negligible changes in proportion. The study reveals and picturizes the dynamic change in diffracting volumes across a wide temperature range. Notably, despite annealing, ∼83% of the bc(o,t) content is still retained (with different lattice parameters), proposing the annealing route to produce unusual metastable lattices of gold.

Ultrashort, 25-fs pulses of x-ray free-electron laser (XFEL) radiation (9.3-keV photons; a pulse energy of 2 mJ) have been micro-focused on the surface of 3-micrometer Cu foil. The interaction experiment has been performed at the European XFEL facility in Schenefeld (Germany). In this contribution emphasis will be placed on the diagnosis and qualitative analysis of emitted highly charged Cu ions using an ion expansion model based on a shifted Maxwell-Boltzmann distribution of ion velocities. This phenomenological approach makes possible to evaluate the charge states of ions belonging to copper stable isotopes Cu-63 and Cu-65 and to determine the voltages by which ion jets are accelerated. This work, describing the properties of ions produced from a mid-Z elemental target exposed to ultrashort x-ray FEL pulses at an irradiance of 10 exa-watts per square centimetre, sheds light on processes occurring in volumetrically heated dense matter on several timescales.

Multimodal imaging of thin-film solar cells has been demonstrated at hard X-ray nanoprobes: simultaneously assessing X-ray beam induced current and X-ray fluorescence, lateral variations in the electrical performance and the distribution of absorber and trace elements can be correlated. Here, we complement the suite of modalities with scanning X-ray diffraction and map the crystallographic structure of Cu(In,Ga)Se2(CIGS) at the nanoscale: in the quaternary compound semiconductor, lattice strain and structural defects induced by tetragonal lattice distortions, steep vertical In/Ga gradients, and lateral inhomogeneities pose a great challenge. Investigating a series of solar cells with varying In/Ga ratio, we probed for the first time a statistically significant number of nearly 500 CIGS grains in the bulk layer of operational cells. Overall, we assessed the entirety of the Cu(In,Ga)Se2 Materials Science Tetrahedron—thanks to, first, extraordinary sensitivity with K-edge excitation allowing to correlate the lateral Cd and In/Ga distribution, local performance, and lattice spacing, second, detection of voids, some filled with CdS, in the CIGS layer, and third, performance-relevant findings from a crystallographic analysis of grain orientation and boundaries. Beyond further optimization of Cu(In,Ga)Se2 photovoltaic cells toward the detailed balance limit of solar-cell conversion efficiency, the developed methodology paves the way to extract a maximum of information from correlative hard X-ray nanoscopy at diffraction-limited storage rings.

Our newly developed technique of stereoscopic ptychography allows us to scan the sample simultaneously with two nanofocused X-ray beams at different angles. The stereoscopic views can, similar to human vision, considerably improve the in-depth perception beyond current limits of pure 2D imaging systems using single optics. We achieved a sub-30 nm lateral resolution and are able to recover phase images of two sample layers, which are separated by less than 500 nm, based on stereo projections. With stereo ptychography we improved the depth resolution by one order of magnitude compared to the established multi-slice ptychography. Here, we take these capabilities a step further by applying them to thicker samples. This is done by combining layer recovery through stereo imaging with multi-slice ptychography.

Hard X-ray ptychography has strongly developed during the last decade, enabling one to visualize structural properties of materials at high spatial resolution. By combining it with multi-slicing or tomographic techniques, optically thick samples can be investigated in 3D. Nevertheless, the depth resolution in multi-slicing is often limited to several micrometers by the ptychographic optical system and a full laminographic or tomographic investigation may be hindered by experimental constraints of limited space or acquisition time. Here, we introduce a stereoscopic imaging system using two inclined nanofocused X-ray beams to illuminate a sample at varying angles at the same time. Similar to human vision, adding these stereoscopic views results in considerably improved in-depth resolution beyond the current limits of pure 2D imaging systems. This is especially promising for experimental applications requiring bulky sample environments.

This study demonstrates a non-destructive approach to investigating the structure of bookbindings in historical manuscripts using high-resolution X-ray computed tomography (CT). We applied the portable CT scanner ENCI to a Georgian codex from the Graz University Library, MS 2058/1, the famous Sinai Lectionary. Three-dimensional reconstructions reveal the complex arrangement of the spine, cords, threads, and gatherings of folios. Individual characters written in vermilion and iron gall ink can be digitally segmented and distinguished. These results highlight the potential of X-ray tomography as a powerful, non-invasive tool for the structural and textual analysis of delicate manuscripts, offering new opportunities to study fragile or partially damaged books while preserving their physical integrity.

We demonstrate live-updating ptychographic reconstruction with the extended ptychographical iterative engine, an iterative ptychography method, during ongoing data acquisition. The reconstruction starts with a small subset of the total data, and as the acquisition proceeds the data used for reconstruction are extended. This creates a live-updating view of object and illumination that allows monitoring the ongoing experiment and adjusting parameters with quick turn around. This is particularly advantageous for long-running acquisitions. We show that such a gradual reconstruction yields interpretable results already with a small subset of the data. We show simulated live processing with various scan patterns, parallelized reconstruction, and real-world live processing at the hard X-ray ptychographic nanoanalytical microscope PtyNAMi at the PETRA III beamline.

Small voids in the absorber layer of thin-film solar cells are generally suspected to impair photovoltaic performance. They have been studied on Cu(In,Ga)Se 2 cells with conventional laboratory techniques, albeit limited to surface characterization and often affected by sample-preparation artifacts. Here, synchrotron imaging is performed on a fully operational as-deposited solar cell containing a few tens of voids. By measuring operando current and X-ray excited optical luminescence, the local electrical and optical performance in the proximity of the voids are estimated, and via ptychographic tomography, the depth in the absorber of the voids is quantified. Besides, the complex network of material-deficit structures between the absorber and the top electrode is highlighted. Despite certain local impairments, the massive presence of voids in the absorber suggests they only have a limited detrimental impact on performance.

An erratum is presented to correct the stated numerical aperture of the employed multilayer Laue lenses in our previously published paper [Opt. Express30, 31519 (2022)10.1364/OE.454863].

The origin of micrometeorites (MMs) from asteroids and comets is well-established, but the relative contribution from these two classes remains poorly resolved. Likewise, determining the precise origin of individual MMs is an open challenge. Here, cosmic-ray exposure ages are used to resolve the spatial origins of 12 MMs collected from urban areas and Antarctica. Their 26Al and 10Be concentration, produced during cosmic-ray irradiation in space, were measured by accelerator mass spectrometry. These data are compared to results from a model simulating the transport and irradiation of the MM precursors in space. This model, for the first time, considers a variety of orbits, precursor particle sizes, compositions and densities and incorporates non-isotropic solar and galactic cosmic-ray flux profiles, depth-dependent production rates, as well as spherical evaporation during atmospheric entry. While the origin for six MMs remains ambiguous, two MMs show a preferential tendency towards an origin in the Inner Solar System (Near Earth Objects to the Asteroid Belt) and four towards an origin in the Outer Solar System (Jupiter Family Comets to the Kuiper Belt). These findings challenge the notion that dust originating from the Outer Solar System is unlikely to survive long-term transport and delivery to the terrestrial planets. This article is part of the theme issue 'Dust in the Solar System and beyond'.

Cuneiform is the earliest known system of writing, first developed for the Sumerian language of southern Mesopotamia in the second half of the 4th millennium BC. Cuneiform signs are obtained by impressing a stylus on fresh clay tablets. For certain purposes, e.g. authentication by seal imprint, some cuneiform tablets were enclosed in clay envelopes, which cannot be opened without destroying them. The aim of our interdisciplinary project is the non-invasive study of clay tablets. A portable X-ray micro-CT scanner is developed to acquire density data of such artifacts on a high-resolution, regular 3D grid at collection sites. The resulting volume data is processed through feature-preserving denoising, extraction of high-accuracy surfaces using a manifold dual marching cubes algorithm and extraction of local features by enhanced curvature rendering and ambient occlusion. For the non-invasive study of cuneiform inscriptions, the tablet is virtually separated from its envelope by curvature-based segmentation. The computational- and data-intensive algorithms are optimized for near-real-time offline usage with limited resources at collection sites. To visualize the complexity-reduced and octree-based compressed representation of surfaces, we develop and implement an interactive application. To facilitate the analysis of such clay tablets, we implement shape-based feature extraction algorithms to enhance cuneiform recognition. Our workflow supports innovative 3D display and interaction techniques such as autostereoscopic displays and gesture control.

Epitaxially grown self-assembled semiconductor quantumdots (QDs)with atom-like optical properties have emerged as the best choicefor single-photon sources required for the development of quantumtechnology and quantum networks. Nondestructive selection of a singleQD having desired structural, compositional, and optical characteristicsis essential to obtain noise-free, fully indistinguishable singleor entangled photons from single-photon emitters. Here, we show thatthe structural orientations and local compositional inhomogeneitieswithin a single QD and the surrounding wet layer can be probed ina screening fashion by scanning X-ray diffraction microscopy and X-rayfluorescence with a few tens of nanometers-sized synchrotron radiationbeam. The presented measurement protocol can be used to cull the bestsingle QD from the enormous number of self-assembled dots grown simultaneously.The obtained results show that the elemental composition and resultantstrain profiles of a QD are sensitive to in-plane crystallographicdirections. We also observe that lattice expansion after a certaincomposition-limitintroduces shear strain within a QD, enabling the possibility of controlledchiral-QD formation. Nanoscale chirality and compositional anisotropy,contradictory to common assumptions, need to be incorporated intoexisting theoretical models to predict the optical properties of single-photonsources and to further tune the epitaxial growth process of self-assembledquantum structures.

The formation of small voids in polycrystalline absorbers has been repeatedly reported, whether after device fabrication or degradation. Although it certainly increases risk of delamination and complicates deposition of additional top layers and cells, it is not clear whether or how detrimental it is for photovoltaic performance. In our study, using synchrotron imaging, we non-destructively probe local performance deficits attributable to voids and highlight the complex 3D nature of structural defects in high-efficiency thin-film CIGS solar cells. We find that, although possibly detrimental at a local level, voids only have a minor effect at the device level, given the abundance of voids and the high efficiency of the cell. Our quantification of the absolute electron densities at the nanoscale may enable the development of adequate comprehensive models simulating structural and electronic defects. In the full presentation, we will show high-resolution images and 3D renderings of nanostructures in CIGS and put them in the context of spatially resolved performance measurements. Furthermore, we will showcase recent developments in X-ray imaging and give an outlook to technical developments at new X-ray sources that will become available in the coming years and enable a further increase of sensitivity and spatial resolution.