I15-1-X-ray Pair Distribution Function (XPDF)
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Janis
Timoshenko
,
David
Kordus
,
Jette K.
Mathiesen
,
Uta
Hejral
,
Patrik
Zeller
,
Gereon
Behrendt
,
Eylül
Öztuna
,
Jihao
Wang
,
Zahra
Gheisari
,
Rene
Eckert
,
Stephan
Reitmeier
,
Andreas
Reitzmann
,
Holger
Ruland
,
Jan
Folke
,
Thomas
Lunkenbein
,
Beatriz
Roldan Cuenya
Diamond Proposal Number(s):
[28439]
Open Access
Abstract: Sample homogeneity on the microscopic scale is critical for the reliable interpretation of x-ray absorption spectra collected in transmission mode. Unfortunately, it is not always easy to ensure it in practice. Especially in operando studies of catalysts and functional materials, the microstructure of the sample can evolve during its operation and even become the key descriptor for understanding structure-property relationships of the material, as exemplified by the transformations taking place in technical iron-based catalysts for ammonia synthesis under operating conditions. Here we present a simple approach for the identification and quantification of the material's microgranular structure effect on its x-ray absorption spectrum. We demonstrate that the quantitative information on the sizes of microscopic sample particles can be extracted from the observed distortions in the x-ray absorption near-edge structure spectra. The obtained insight can also be used to correct for the artifacts in extended x-ray absorption fine structure fitting, associated with the presence of microscopic inhomogeneities in the sample.
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Jul 2025
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B16-Test Beamline
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Diamond Proposal Number(s):
[28722]
Open Access
Abstract: This paper presents a novel method of using cumulative integrated intensity (CII) to analyse rocking curve x-ray diffraction imaging (RC-XRDI) data. This method overcomes several limitations of traditional complex non-ideal curve fitting, which often results in inaccurate peak detection and full width at half maximum (FWHM) extraction. These complex non-ideal rocking curves arise in cases where additional features are present, such as peak splitting and multiple peaks. The application of the method also avoids the need for curve fitting and time-consuming calculations, allowing the extraction of peak widths at various normalized height-intensities (FWxM) and revealing extra information about defects. By analysing the broadening and peak position of the rocking curves for different defects, RC-XRDI provides insights into the nature and distribution of these defects within the material. Applied to RC-XRDI of a 4H-SiC 10 μm-thick homo-epitaxial layer on a substrate, the CII method was used to detect shifts in peak position and generate maps of full width at 1%, 10%, and 50% of maximum intensity, offering a detailed view of defect-induced broadening. Our results demonstrate that the CII method provides improved accuracy and requires fewer computations compared to curve-fitting techniques, making it particularly useful where precise defect characterization is critical. Moreover, background intensity was detected pixel-by-pixel using cubic smoothing splines, and the CII method provided robust validation for the precision of this background detection.
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May 2025
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Open Access
Abstract: High-resolution imaging has revolutionized materials science by offering detailed insights into the atomic structures of materials. Electron microscopy and spectroscopy rely on analysing backscat- tered and transmitted electrons as well as stimulated radiation emission to form structural and chemical maps. These signals contain information about the elastic and inelastic electron-scattering processes within the sample, including collective and single electron excitations such as plasmons, inter- and intraband transitions. In this study, ab initio and Monte Carlo simulations were performed to investigate the behaviour of high-energy primary and secondary electrons in scanning transmission experiments on CsPbBr$_3$ nanosamples. CsPbBr$_3$ is a perovskite material known for its high photoluminescence quantum yield, making it promising for applications in light-emitting devices and solar cells. This study explores and estimates the reflection and transmission of primary and secondary electrons based on their kinetic energy as well as sample thickness and electron affinity. The spatial distribution and energy spectra of the secondary electrons are also examined and calculated to understand their generation depth and energy dynamics. These findings establish a theoretical framework for studying electron-material interactions and can aid in optimizing scanning microscopy techniques for imaging and characterizing advanced materials.
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Apr 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Abstract: The technique of extended-range high-energy-resolution fluorescence detection (XR-HERFD), developed from X-ray absorption spectroscopy, X-ray emission spectroscopy and resonant inelastic X-ray scattering (RIXS), has been used to successfully observe a new X-ray fluorescent satellite in manganese. The experimental methodology, spectral processing and analysis, and how statistical information and structure can be defined, extracted and used from HERFD spectra are detailed. Novel approaches to measure and improve accurate data uncertainty in XR-HERFD, HERFD and RIXS data sets are also presented. This includes definitions of intrinsic resolution and improvements to the resolution of the output and data by a factor of two relative to raw data or standard processing. Novel systematics common in HERFD and RIXS experiments are detailed, including background subtraction and elastic Bragg harmonics, with approaches to dealing with them.
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Dec 2024
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Valerio
Bellucci
,
Sarlota
Birnsteinova
,
Tokushi
Sato
,
Romain
Letrun
,
Jayanath C. P.
Koliyadu
,
Chan
Kim
,
Gabriele
Giovanetti
,
Carsten
Deiter
,
Liubov
Samoylova
,
Ilia
Petrov
,
Luis
Lopez Morillo
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Rita
Graceffa
,
Luigi
Adriano
,
Helge
Huelsen
,
Heiko
Kollmann
,
Thu Nhi
Tran Calliste
,
Dusan
Korytar
,
Zdenko
Zaprazny
,
Andrea
Mazzolari
,
Marco
Romagnoni
,
Eleni Myrto
Asimakopoulou
,
Zisheng
Yao
,
Yuhe
Zhang
,
Jozef
Ulicny
,
Alke
Meents
,
Henry N.
Chapman
,
Richard
Bean
,
Adrian
Mancuso
,
Pablo
Villanueva-Perez
,
Patrik
Vagovic
Open Access
Abstract: X-ray multi-projection imaging (XMPI) is an emerging experimental technique for the acquisition of rotation-free, time-resolved, volumetric information on stochastic processes. The technique is developed for high-brilliance light-source facilities, aiming to address known limitations of state-of-the-art imaging methods in the acquisition of 4D sample information, linked to their need for sample rotation. XMPI relies on a beam-splitting scheme, that illuminates a sample from multiple, angularly spaced viewpoints, and employs fast, indirect, X-ray imaging detectors for the collection of the data. This approach enables studies of previously inaccessible phenomena of industrial and societal relevance such as fractures in solids, propagation of shock waves, laser-based 3D printing, or even fast processes in the biological domain. In this work, we discuss in detail the beam-splitting scheme of XMPI. More specifically, we explore the relevant properties of X-ray splitter optics for their use in XMPI schemes, both at synchrotron insertion devices and XFEL facilities. Furthermore, we describe two distinct XMPI schemes, designed to faciliate large samples and complex sample environments. Finally, we present experimental proof of the feasibility of MHz-rate XMPI at the European XFEL. This detailed overview aims to state the challenges and the potential of XMPI and act as a stepping stone for future development of the technique.
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Nov 2024
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[21780]
Open Access
Abstract: Welded components contain complex residual stress fields which are important to quantify when assessing their structural integrity. Often such assessments involve finite element simulation of the components; thus it is essential to include residual stress fields in the model. While previous methods have been proposed to include residual stresses in finite element models (e.g. using iterative methods or eigenstrain reconstruction of residual stresses), these can be theoretically cumbersome and computationally expensive. In this work a novel technique for reconstruction of residual stresses in welds is presented, based on iterative stress imposition and relaxation, and using limited residual stress data from energy dispersive X-ray diffraction (EDXD) measurements. This method is validated using a combination of neutron imaging of small sections of the weld and finite element analysis. A root mean squared (RMS) error of 127.26
ɛ
was achieved between the FE model and the EDXD measurement. Although the method is only viable for relatively simple geometries such as pipes and plates, this covers the most likely use cases in relevant industries such as nuclear energy. Reconstruction of residual stress fields can assist structural integrity assessments by requiring less measured residual stress data. As well as reducing measurement costs our method may enable less overly-conservative assessments, particularly for flaws that do not lie on a weld centreline. This work also demonstrates that neutron imaging residual strain measurement is a valuable tool for validating methods of weld residual stress modelling.
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Nov 2024
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[25602]
Open Access
Abstract: By developing a 3D X-ray modeling and spatially correlative imaging method for fibrous collagenous tissues, this study provides a comprehensive mapping of nanoscale deformation in the collagen fibril network across the intact bone-cartilage unit (BCU), whose healthy functioning is critical for joint function and preventing degeneration. Extracting the 3D fibril structure from 2D small-angle X-ray scattering before and during physiological compression reveals of dominant deformation modes, including crystallinity transitions, lateral fibril compression, and reorientation, which vary in a coupled, nonlinear, and correlated manner across the cartilage-bone interface. A distinct intermolecular arrangement of collagen molecules, and enhanced molecular-level disorder, is found in the cartilage (sliding) surface region. Just below, fibrils accommodate tissue strain by reorientation, which transitions molecular-level kinking or loss of crystallinity in the deep zone. Crystalline fibrils laterally shrink far more (20×) than they contract, possibly by water loss from between tropocollagen molecules. With the calcified plate acting as an anchor for surrounding tissue, a qualitative switch occurs in fibrillar deformation between the articular cartilage and calcified regions. These findings significantly advance this understanding of the complex, nonlinear ultrastructural dynamics at this critical interface, and opens avenues for developing targeted diagnostic and therapeutic strategies for musculoskeletal disorders.
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Nov 2024
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[31385]
Open Access
Abstract: A free-standing and compact reaction cell for combined in situ/operando x-ray spectroscopy, scattering, and imaging measurements at high pressures and high temperatures is described. The cell permits measurements under realistic operating conditions (up to 50 bar and 1000 °C), under static and flow conditions (up to 100 ml/min), over a wide range of hard x-ray energies, variable detection modes (transmission, fluorescence, and scattering), and at all angles of rotation. An operando XAS, x-ray fluorescence, x-ray computed tomography, and x-ray diffraction computed tomography case study on the reduction of a heterogeneous catalyst is presented to illustrate the performance of the reaction cell.
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Oct 2024
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Open Access
Abstract: Background:
A key issue with the established method of cryo-electron tomography (Cryo- ET) often lies in the challenge of accurately locating complexes or proteins of interest within the crowded cellular environment of the generated tomograms. This project aims to use cryo-scanning transmission electron microscopy (STEM) to highlight regions of tomograms containing the protein of interest by tagging with a minimally-sized heavy atom nanoparticle for downstream processing. A fine balance must be achieved between resolution, signal-to-noise ratio (SNR), depth of focus, and damage to the lamella.
Methods:
A scan generator offers alternative (non-raster) methods of scanning the beam to offset damage and allow higher electron fluences to be used without compromising ice quality. Small raster and interleaved scans (< 200 nm) were compared in the same quantifoil hole of vitreous ice, using an equal overall electron fluence and flux.
Analysis of elastic scattering cross section theory yields an approximate minimal size of nanoparticles for detection in STEM of vitreous amorphous specimens. Single particle-like sample preparation was employed to freeze varying sizes of gold nanoparticles (0.8-4 nm) in different thicknesses of ice. These were subsequently exposed to STEM to assess a drop-off in SNR with increasing collection angles using an annular dark field detector.
Results:
Scanning in an alternative fashion using long dwell times demonstrated a significant reduction in mass loss. Raster scanning appeared to be marginally better than interleaved scanning when using shorter dwell times (20 μs), as evidenced by greater loss of intensity in the scanned areas, normalised to reference areas taken within the same hole of vitreous ice. However, using longer dwell times (250 μs or 500 μs) reversed this effect, showing raster scanning to be significantly more damaging than interleaved, melting the ice completely in thin samples for raster scanning, whilst maintaining the ice intact using an interleaved sequence.
Conclusions:
These findings provide valuable first steps toward optimizing cryo-STEM imaging for detecting nanoparticles and correlating these findings with in-situ Transmission Electron Microscopy (TEM).
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Oct 2024
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E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Open Access
Abstract: Background incl. aims: Conjugated polymers are an important class of organic light emitting diodes (OLEDs) and organic solar cells (OSCs). These materials are predominantly semi-crystalline or amorphous with intricate molecular packing and mixed variety of structural orders and disorders [1]. The susceptibility of these materials to ‘burn-in degradation’ [2] can induce blend-demixing and photo-induced ordering/disordering [3], thereby resulting in the performance losses of the devices [4]. Controlling this performance degradation during operation necessitates an understanding in changes in chemical structures and structural disorders at the nanoscale – the length scale commensurate with the transport of charge carriers. Yet direct nanoscale characterisation is limited for polymer semiconductors and their associated devices due to the irreversible changes in these materials structure when exposed to high-energy ion and electron beam conditions [5]. Here, we advance the structural characterisation of polymer semiconductors, whether in the form of free-standing films or cross-sectioned lamella, using low-dose four-dimesion scanning transmission electron microscopy (4D-STEM), enabling the analysis of the molecular packing, crystallinity, and atomic arrangement in the polymer semiconductors in response to temperature and ion milling-induced damage. Methods: Low-dose 4D-STEM analysis was conducted using established nanobeam scanning electron diffraction alignment at electron Physical Science Imaging Centre (ePSIC), Diamond Light Source. In particular, Merlin-Medipix detector and <1 mrad convergence semi-angle with 1-2 pA in probe current at 300 kV were used to minimize radiolytic damage. We obtained data at a range of camera lengths to enable both mapping of crystalline domains from Bragg scattering as well as reciprocal space (variance measures) and real space electron Pair Distribution Function (ePDF) analysis of disordered and amorphous regions. The materials under examination were free-standing polymer films (F8:F8BT, 1:1), prepared by spin-coating onto PDOT:PSS/ITO/Glass substrates. Subsequently, the multi-layered sample was submerged in deionized water, and the F8:F8BT films were floated onto carbon support films for 4D- STEM analysis. Additionally, we developed cryo-Focused Ion Beam (cryo-FIB) protocols to facilitate the structural examination of the cross-sectioned device model, Glass/ITO/PDOT:PSS/F8:F8BT (1:1). Results: The developed techniques reveal the formation of nano-crystalline domains in the F8:F8BT films after heat treatment. These domains are attributed to the crystallisation of F8 polymers, as evidenced by indexing some diffraction patterns aligning along the zone axis. Additionally, ePDF analysis allows us to characterise the atomic structures in amorphous areas with varying contrast. The analysis indicates that there were no chemical changes in the F8:F8BT blends induced by temperature. However, partial phase segregation occurred, as also supported by low-dose EELS analysis. We extended these analyses to a cross-sectioned device model prepared by cryo-FIB, and the findings demonstrate that our cryo-FIB protocol preserves the crystalinity of the polymer blends. ePDF shows that cryo-FIB milling does not alter the chemical structures of the films, i.e. intramolecular structure, but does affect the intermolecular arrangement. Conclusion: The developed electron microscopy techniques enable the characterisation of microstructures and nanoscale atomic arrangements in beam-sensitive polymer semiconductors, paving a pathway for examining phase segregation and chemical changes resulting from the burn-in degradation. By doing so, effective strategies can be developed to minimise structural degradation in polymer semiconductors, thereby preventing performance losses during operation.
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Oct 2024
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