E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[39072]
Open Access
Abstract: Potassium-ion batteries (KIBs) are a promising beyond–lithium-ion chemistry, offering advantages similar to sodium-ion systems in terms of earth-abundant materials and safety, with the additional benefit of reversible graphite intercalation and potential for improved low-temperature performance. These features make KIBs attractive for low-cost electric vehicles and stationary battery energy storage systems. However, they currently fall short of the cycle life required by these applications. A major source of capacity fade is instability of the solid electrolyte interphase (SEI), which is influenced by electrolyte chemistry, temperature, and the electrochemical history of the cell. Many studies use potassium metal as a proxy to investigate SEI behaviour on graphite. On potassium metal, the SEI can form chemically via direct reaction with the electrolyte or electrochemically during potassium plating. In contrast, during charging of a graphite electrode, SEI formation occurs exclusively through electrochemical reduction. It therefore remains unclear to what extent the SEI formed on potassium metal is representative of that formed on graphite. Here, we employ X-ray photoelectron spectroscopy (XPS) to probe differences between chemical and electrochemical SEI formation on potassium metal, graphite, and inert electrodes in two contrasting potassium bis(fluorosulfonyl)imide (KFSI)-based electrolytes: 1 m KFSI in tetraethylene glycol dimethyl ether (G4) and 1 m KFSI in 1,3-dioxane (13-DX). Four-dimensional scanning transmission electron microscopy (4D-STEM) phase mapping provides complementary structural insight. We establish relationships between SEI chemistry, electrolyte composition, electrode material, formation pathway, and applied potential, offering guidance for rational electrolyte design.
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Apr 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
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Alexander I.
Large
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Henry
Hoddinott
,
Haamidah
Sana
,
Elizabeth
Jones
,
James J. C.
Counter
,
Matthijs
Van Spronsen
,
Santosh
Kumar
,
David C.
Grinter
,
Pilar
Ferrer
,
Bernd
Von Issendorff
,
Richard Edward
Palmer
,
Georg
Held
Diamond Proposal Number(s):
[29320, 29935, 33291]
Open Access
Abstract: The importance of cluster-size eects in heterogeneous catalysis is now well recognized. X-ray photoelectron spectroscopy (XPS) is an obvious technique to study size-dependent changes in the chemical composition and electronic structure of catalyst nanoparticles. However, as XPS is an averaging technique based on the detection of electrons, experiments require a narrow distribution of cluster size and a conducting homogeneous support in order to avoid sample charging, which would prevent accurate measurements of chemical shifts. Traditional methods of catalyst synthesis by impregnation/calcination of support powders lead to very large particle size distributions (typically ± 50 %) and insulating samples. They therefore fail both of the above criteria and make it extremely dicult to extract precise sample characterisation. Here we present an alternative approach designed to enable XPS analysis in vacuum and under reaction conditions, whereby: (i) nanoparticles are synthesized by gas condensation and passed through a mass filter, which allows size selection in the range of 1 to 10000 atoms with typically ±4% accuracy; (ii) these particles are deposited onto a thin Al2O3 film grown on Al foil, which mimics the properties of conventional alumina supports while being conductive enough to avoid any charging-related artefacts in the XPS spectra. In vacuum, size-dependent Pd 3d binding-energy shifts up to 1.65 eV were recorded for supported Pd nanoparticles. Changes in the chemical composition of Pd nanoparticles were studied by near-ambient pressure (NAP)-XPS under dry and wet reaction conditions for methane oxidation (CH4 + O2 [+ H2O]) in the temperature range between 150 ◦C and 450 ◦C. Under dry reaction conditions large Pd particles appeared to oxidise almost fully to Pd(II), whereas smaller clusters showed a mix of Pd(0) and Pd(II) oxidation states. Under wet conditions, oxidation starts at lower temperatures and particles of all sizes were fully oxidised when the highest temperature was reached. Sintering during the temperature ramp cannot be excluded, especially for the smaller particles, and may be part of the reason for the dierent behaviour under wet conditions. This study clearly shows composition changes which are particle-size dependent and demonstrate.
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Mar 2026
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I08-Scanning X-ray Microscopy beamline (SXM)
I14-Hard X-ray Nanoprobe
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Open Access
Abstract: Advances in X-ray nanoprobe beamlines at synchrotrons across the world present exciting opportunities for rich multimodal imaging of biomineral structures and their formation processes. The combination of techniques provides a sensitive probe of both chemistry and structure, making X-ray nanoprobes an important tool for investigating crystallite growth and orientations, interfaces and assembly of building blocks into hierarchical structures. A discussion of these capabilities is presented with reference to recent examples using a range of nanoprobe imaging techniques for investigating enamel structure, as well as coccolith properties. Key opportunities for the use of X-ray nanoprobes lie in exploiting the penetrating power and coherence properties of synchrotron X-rays in order to image in situ processes or apply coherent diffractive imaging techniques to obtain higher resolutions. To this end initial results demonstrating the observation of calcium phosphate mineralisation, in a liquid environment, using nano-X-ray fluorescence mapping are presented, and the role of X-ray dose and beam induced effects is considered. Finally novel results from tomographic ptychography imaging of a Mytilus Edulis mussel shell calcite prisms are discussed, where the segmentation of the phase density into organic and mineral content give insights into the mechanisms underlying mineral prism formation and the role of the organic matrix in biomineralisation.
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May 2025
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I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[23602, 28688]
Open Access
Abstract: Coccolithophore microalgae intracellularly produce nanostructured calcitic platelets, known as coccoliths, through a biologically-controlled mineralization process. Mature coccoliths are secreted to the cell surface and assembled into a shell that envelops the cell. The large-scale global production of coccoliths, followed by their sedimentation to the ocean floor, significantly contributes to carbon cycling. Despite progress in understanding the biomineralization pathway of coccoliths, we are still limited in our ability to predict how future climate conditions will impact coccolith formation and thus ocean carbon fluxes. Investigating coccolith biomineralization at the single-cell level is therefore critical to advance our understanding but remains challenging since current imaging techniques lack the combined spatial and temporal resolution coupled with element-specific detection to follow processes in situ. In light of this gap, nanobeam-scanning X-ray fluorescence microscopy (nano-XRF) in the hard X-ray regime is employed here to investigate the intracellular elemental distribution of the coccolithophore Gephyrocapsa huxleyi (formerly Emiliania huxleyi) achieving a resolution of 100 nm and elemental detection from phosphorus (P) to zinc (Zn). Calcium- and phosphorus-rich intracellular bodies, previously proposed to be involved in coccolith biomineralization, were observed in cells initially prepared ex situ by drying. Interestingly, nano-XRF imaging reveals metal species (e.g., Mn, Fe, Zn) within these bodies that were not detected in earlier studies, suggesting multiple biological roles for these structures. Moving towards native-state imaging, G. huxleyi was then imaged in hydrated state using a dedicated liquid cell device. Measurements were performed on G. huxleyi cells both with and without coccolith shell in sea water medium and compared to those of dried cells, demonstrating comparable image quality. The future potential and limitations of liquid cell nano-XRF imaging for coccolithophores and other microorganisms are further discussed.
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Mar 2025
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I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[32152]
Open Access
Abstract: A biomimetic peptide (P11-4), which is predominantly negatively-charged, facilitates the nucleation of hydroxyapatite (HAp). P11-4 self-assembles into fibrils via β-sheet formation, creating a 3D-gel-network. Here, X-ray nanoimaging and correlative scanning electron microscopy (SEM) investigated P11-4’s surface chemistry and its ability to nucleate HAp in the absence of the 3D-gel-network. P11-4 was deposited on silicon nitride (SiN) windows, which were immersed in a mineralising solution (MS) and then mapped using nano-X-ray fluorescence (n-XRF) and differential phase contrast imaging at the hard X-ray nanoprobe beamline (I14) at Diamond Light Source. Elemental calcium and phosphorus maps were extracted using n-XRF, and compared with and without P11-4. The windows were subsequently mapped using SEM and Energy Dispersive Spectroscopy (EDS) to confirm the morphology and elemental compositions of the formed structures. The calcium:phosphorus ratios were calculated to identify the phases formed. P11-4 increased the calcium and phosphorus signals with time in MS compared to the control (without P11-4). After 12 hours in MS, calcium ions accumulated on the deposited β-sheets, attracting phosphorus ions at later time points. From the morphology in the images and EDS analysis, the spherical calcium phosphate (CaP) structures appeared to be amorphous, indicating the formation of precursors, likely amorphous CaP, at early time points. In the presence of P11-4, these structures grew and fused into larger CaP formations over time, unlike in the control. Nano-imaging techniques highlighted that P11-4’s surface chemistry accelerates the kinetics and controls the initial CaP crystallisation process, resulting in an amorphous CaP phase.
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Mar 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Jake M.
Seymour
,
Ekaterina
Gousseva
,
Frances
Towers Tompkins
,
Lewis G.
Parker
,
Najaat O.
Alblewi
,
Coby J.
Clarke
,
Shusaku
Hayama
,
Robert G.
Palgrave
,
Roger A.
Bennett
,
Richard P.
Matthews
,
Kevin R. J.
Lovelock
Diamond Proposal Number(s):
[24305, 28565, 30597]
Open Access
Abstract: Using a combination of liquid-phase experimental X-ray spectroscopy experiments and small-scale calculations we have gained new insights into the speciation of halozincate anions in ionic liquids (ILs). Both core and valence X-ray photoelectron spectroscopy (XPS) were performed directly on the liquid-phase ILs, supplemented by Zn 1s X-ray absorption near edge structure (XANES) spectroscopy. Density functional theory (DFT) calculations were carried out on both 1- and 2- halozincate anions, in both a generalised solvation model SMD (Solvation Model based on Density) and the gas phase, to give XP spectra and total energy differences; time-dependent DFT was used to calculate XA spectra. Speciation judgements were made using a combination of the shape and width of experimental spectra, and visual matches to calculated spectra. For 2- halozincate anions, excellent matches were found between experimental and calculated XP spectra, clearly showing that only 2- halozincate anions were present at all zinc halide mole fraction, x, studied. At specific x (0.33, 0.50, 0.60) only one halozincate anion was present; equilibria of different halozincate anions at those x were not observed. All findings show that chlorozincate anion and bromozincate anion speciation matched at the same x. Based on the results, predictions are made of the halozincate anion speciation for all x up to 0.67. Caution is advised when using differences in calculated total energies obtained from DFT to judge halozincate anion speciation, even when the SMD was employed, as predictions based on total energy differences did not always match the findings from experimental and calculated spectra. Our findings clearly establish that the combination of high-quality experimental data from multiple spectroscopies and a wide range of calculated structures are essential to have high confidence in halozincate anion speciation identification.
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Apr 2024
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Open Access
Abstract: Poly(Ni-btt), an organometallic coordination polymer (OMCP) characterized by the coordination between benzene-1,2,4,5-tetrakis(thiolate) (btt) and Ni2+ ions, has been recognized as a promising p-type thermoelectric material. In this study, we employed a constitutional isomer based on benzene-1,2,3,4-tetrakis(thiolate) (ibtt) to generate the corresponding isomeric polymer, poly(Ni-ibtt). Comparative analysis of poly(Ni-ibtt) and poly(Ni-btt) reveals several common infrared (IR) and Raman features attributed to their similar square-planar nickel-sulfur (Ni-S) coordination. Nevertheless, these two polymer isomers exhibit substantially different backbone geometries. Poly(Ni-btt) possesses a linear backbone, whereas poly(Ni-ibtt) exhibits a more undulating, zigzag-like structure. Consequently, poly(Ni-ibtt) demonstrates slightly higher solubility and an increased bandgap in comparison to poly(Ni-btt). The most noteworthy dissimilarity, however, manifests in their thermoelectric properties. While poly(Ni-btt) exhibits p-type behaviour, poly(Ni-ibtt) demonstrates n-type carrier characteristics. This intriguing divergence prompted further investigation into the influence of OMCP backbone geometry on the electronic structure and, particularly, the thermoelectric properties of these materials.
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Sep 2023
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I18-Microfocus Spectroscopy
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Martin V.
Appleby
,
Rory A.
Cowin
,
Iona
Ivalo
,
Samantha L.
Peralta-Arriaga
,
Craig C.
Robertson
,
Stuart
Bartlett
,
Ann
Fitzpatrick
,
Andrew
Dent
,
Gabriel
Karras
,
Sofia
Diaz-Moreno
,
Dimitri
Chekulaev
,
Julia A.
Weinstein
Diamond Proposal Number(s):
[28403, 30784]
Open Access
Abstract: The study aims to understand the role of the transient bonding in the interplay between the structural and electronic changes in heteroleptic Cu(I) diimine diphosphine complexes. This is an emerging class of photosensitisers which absorb in the red region of the spectrum, whilst retaining a sufficiently long excited state lifetime. Here, the dynamics of these complexes are explored by transient absorption (TA) and time-resolved infrared (TRIR) spectroscopy, which reveal ultrafast intersystem crossing and structural distortion occurring. Two potential mechanisms affecting excited state decay in these complexes involve a transient formation of a solvent adduct, made possible by the opening up of the Cu coordination centre in the excited state due to structural distortion, and by a transient coordination of the O-atom of the phosphine ligand to the copper center. X-ray absorption studies of the ground electronic state have been conducted as a prerequisite for the upcoming X-ray spectroscopy studies which will directly determine structural dynamics. The potential for these complexes to be used in bimolecular applications is confirmed by a significant yield of singlet oxygen production.
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Jul 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Open Access
Abstract: Noncovalent interactions are essential in the formation and properties of a diverse range of materials. However, reliably identifying the noncovalent interactions remains challenging using conventional methods such as X-ray diffraction, especially in nanocrystalline, poorly crystalline or amorphous materials which lack long-range lattice periodicity. Here, we demonstrate the accurate determinations of deviations in the local structure and tilting of aromatic rings during the temperature-induced first order structural transition in the 1:1 adduct of 4,4’-bipyridinium squarate from low temperature form HAZFAP01 to high temperature HAZFAP07. This work demonstrates how Pair Distribution Function (PDF) analyses can improve our understanding of local structural deviations resulting from noncovalent bonds and guide the development of novel functional materials.
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Jan 2023
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Open Access
Abstract: We present a charge density study of two linkage isomer photoswitches, [Pd(Bu4dien)(NO2)]BPh4.THF (1) and [Ni(Et4dien)(NO2)2] (2) using Hirshfeld Atom Refinement (HAR) methods implemented via the NoSpherA2 interface in Olex2. HAR is used to explore the electron density distribution in the photoswitchable molecules of 1 and 2, to gain an in-depth understanding of key bonding features and their influence on the single-crystal-to-single-crystal reaction. HAR analysis is also combined with ab initio calculations to explore the non-covalent interactions that influence physical properties of the photoswitches, such as the stability of the excited state nitrito-(η1-ONO) isomer. This insight can be fed back into the crystal engineering process to develop new and improved photoswitches that can be optimised towards specific applications.
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Dec 2022
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