I18-Microfocus Spectroscopy
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Ian T.
Burke
,
Patrizia
Onnis
,
Alex L.
Riley
,
Catherine J.
Gandy
,
Violeta
Ramos
,
Gavyn K.
Rollinson
,
Patrick
Byrne
,
Richard A.
Crane
,
Karen A.
Hudson-Edwards
,
Elin
Jennings
,
William M.
Mayes
,
J. Frederick W.
Mosselmans
,
Adam P.
Jarvis
Diamond Proposal Number(s):
[29808, 31675]
Open Access
Abstract: The erosion of legacy coastal municipal solid waste landfill sites will result in the dispersion of particulate material into nearby ecosystems with potential for effects on marine populations. Information on the speciation and solid phase associations of metal(loid) contaminants will help to predict contaminant behaviour and better understand ecosystem risks. Here, we investigate the solid phase composition of, and metal(loid) leaching from, fine fraction materials recovered from three actively eroding coastal landfill sites. High concentrations of a range of potentially toxic elements (As, Cd, Cr, Cu, Pb, Ni and Zn) were present in multiple samples, but metal(loid) leaching rates were very low (≪1 wt%) in both deionised water and seawater solutions. Therefore, particulate dispersion is the most likely mode of contaminant transport occurring at these sites. The fine fraction materials were dominated by fine sand sized (63–180 μm) quartz grains and silt sized (<63 μm) matrix components, which were likely to be poorly retained on beaches and easily transported offshore. Four priority contaminants (As, Cu, Pb and Zn) were found to occur primarily in adsorbed or precipitate forms, as either coatings on other particles or as discrete <10 μm particles. Dilution of these fine-grained contaminated particles within natural pelitic sediments will likely reduce the overall ecosystems impacts; but the risks to filter and bottom feeding organisms, and the potential for biomagnification across trophic levels are poorly understood.
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Oct 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[23496]
Open Access
Abstract: Arsenic immobilization in soils and sediments is primarily controlled by its sorption onto or incorporation into reactive soil minerals, such as iron (oxyhydr)oxides. However, coexisting ions (e.g., dissolved bicarbonate, phosphate, silica, and organic matter) can negatively impact the interaction of the toxic arsenate species with iron (oxy)hydroxides. Of special note is inorganic phosphate, which is a strong competitor for sorption sites due to its analogous chemical and structural nature to inorganic arsenate. Much of our understanding of this competing nature between phosphate and arsenate focuses on the impact on mineral sorption capacities and kinetics. However, we know very little about how coexisting phosphate will alter the stability and transformation pathways of arsenate-bearing Fe (oxyhydr)oxides. In particular, the long-term fate and behavior regarding arsenate immobilization are unknown under anoxic conditions. Here, we document, through mineral transformation reactions, the immobilization of both phosphate (P) and arsenate [As(V)] in secondary mineral products and characterize their changing compositions during the transformations. We did this while controlling the initial P/As(V) ratios. Our results document that, in the absence or at low P/As(V) ratios, the initial ferrihydrite rapidly transforms to green rust sulfate (GRSO4), which further transforms into magnetite after 180 days. Meanwhile, high P/As(V) ratios resulted in a mixture of GRSO4 and vivianite, with magnetite as a minor fraction. Invariably, the speciation and partitioning of As(V) were also affected by the P/As(V) ratio. A higher P/As(V) ratio also led to a faster partial reduction of mineral-bound As(V) to As(III). The most important finding is that the initial ferrihydrite-bound As(V) became structurally incorporated into magnetite [low P/As(V) ratio] or vivianite [high P/As(V) ratio] and was thus immobilized and not labile. Overall, our results highlight the influence of coexisting phosphate in controlling the toxicity and mobility in anoxic, Fe2+-rich subsurface settings, such as contaminated aquifers.
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Jun 2025
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B18-Core EXAFS
I20-Scanning-X-ray spectroscopy (XAS/XES)
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Thomas S.
Neill
,
Katherine
Morris
,
Scott
Harrison
,
Pete
Apps
,
Nick
Bryan
,
Stephen
Parry
,
J. Frederick W.
Mosselmans
,
Giannantonio
Cibin
,
Bruce
Rigby
,
Francis R.
Livens
,
Samuel
Shaw
Diamond Proposal Number(s):
[17243, 21441]
Open Access
Abstract: Colloids present a challenge for nuclear decommissioning and disposal due to their potential to mobilise radionuclides. Waste retrieval and decommissioning of storage ponds for spent nuclear fuel and silos for radioactive waste at the Sellafield nuclear facility, UK, are high priorities. The particulates characterised here originate from facilities >60 years old and provide a unique opportunity to investigate the long-term fate of radionuclides in an aquatic, engineered storage environment. Radioactive effluents were obtained from a legacy pond and characterised using ultrafiltration, transmission electron microscopy (TEM) and actinide L3 edge X-ray absorption spectroscopy (XAS). TEM analysis showed discrete UO2-like nanoparticles, 5-10 nm in size, often co-associated with Mg-Al- and Fe-(oxyhydr)oxide colloidal phases. Uranium XAS indicated a mix of uranium oxidation states with EXAFS suggesting U(IV)-oxide nanoparticles and sorbed U(VI). Pu XANES identified Pu(IV) as the dominant oxidation state. Both U and Pu associates with large, Mg/Al- and Fe-(oxyhydr)oxide agglomerates highlights the potential for pseudo-colloid formation, explaining the basis of current particle filtration / abatement of technology. This study, which examines novel samples from a complex, highly radioactive facility using advanced techniques, provides a new understanding of radionuclide speciation and mobility in these environments and informs radioactive effluent treatment and disposal.
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Feb 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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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[28859, 30113]
Open Access
Abstract: Here, the novel technique of extended-range high-energy-resolution fluorescence detection (XR-HERFD) has successfully observed the n = 2 satellite in manganese to a high accuracy. The significance of the satellite signature presented is many hundreds of standard errors and well beyond typical discovery levels of three to six standard errors. This satellite is a sensitive indicator for all manganese-containing materials in condensed matter. The uncertainty in the measurements has been defined, which clearly observes multiple peaks and structure indicative of complex physical quantum-mechanical processes. Theoretical calculations of energy eigenvalues, shake-off probability and Auger rates are also presented, which explain the origin of the satellite from physical n = 2 shake-off processes. The evolution in the intensity of this satellite is measured relative to the full Kα spectrum of manganese to investigate satellite structure, and therefore many-body processes, as a function of incident energy. Results demonstrate that the many-body reduction factor S02 should not be modelled with a constant value as is currently done. This work makes a significant contribution to the challenge of understanding many-body processes and interpreting HERFD or resonant inelastic X-ray scattering spectra in a quantitative manner.
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Jul 2024
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[28515]
Open Access
Abstract: Mn-doped UO2 is under consideration for use as an accident tolerant nuclear fuel. We detail the synthesis of Mn-doped UO2 prepared via a wet co-precipitation method, which was refined to improve the yield of incorporated Mn. To verify the Mn-doped UO2 defect chemistry, X-ray absorption spectroscopy at the Mn K-edge was performed, in addition to X-ray diffraction, Raman spectroscopy and high-energy resolved fluorescence detection X-ray absorption near edge spectroscopy at the U M4-edge. It was established that Mn2+ directly substitutes for U4+ in the UO2 lattice, accompanied by oxygen vacancy (Ov) charge compensation. In contrast to other divalent-element doped UO2 materials, compelling evidence for U5+ in a charge compensating role was not found. This work furthers understanding of the structure and crystal chemistry of Mn-doped UO2, which could show potential advantages as a novel efficient advanced nuclear fuel.
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Jan 2024
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[4516]
Open Access
Abstract: Titanium occurs as Ti3+, in addition to the more usual Ti4+, in extraterrestrial materials such as Lunar basalts and chondritic meteorites. The proportion of Ti as Ti3+ was investigated by Ti K-edge X-ray absorption near edge structure (XANES) spectroscopy for five silicate glass compositions quenched from melts equilibrated at 1400°C, atmospheric pressure, and oxygen fugacities (fO2) in log units relative to the fayalite-magnetite-quartz (FMQ) buffer from FMQ+3.3 to FMQ-10.2 (+6.6 to -6.9 log units relative to the iron-wüstite, IW, buffer). All spectra could be well fit using a linear combination of the spectra recorded from the most oxidised and reduced samples of the same composition, indicating that the samples only contain two Ti species. Ti3+/ΣTi (where ΣTi = Ti3+ + Ti4+) = 0 for the most oxidised samples but is unknown for the most reduced. Thus, the linear combination fit results were used in a regression model in which Ti3+/ΣTi of the reduced end-member was varied to give Ti3+/ΣTi values of the other samples that best fit the thermodynamically expected dependence of Ti3+/ΣTi on fO2. The most reduced samples were found to have Ti3+/ΣTi ∼ 0.6. The resulting modified equilibrium constants of the Ti oxidation reaction, logK', are linearly correlated with the optical basicity (
parameterisation of melt composition, such that as
increases, Ti3+/ΣTi decreases, at constant fO2. This correlation allows Ti3+/ΣTi to be predicted for other compositions and, assuming that the temperature dependence of Ti3+/Ti4+ is parallel to FMQ, a general equation relating Ti3+/Ti4+ to fO2 was obtained: log(Ti3+/Ti4+) = -0.25ΔFMQ - 0.32(19) - 3.44(32)
. This equation was used to predict Ti3+/ΣTi as a function of fO2 for high-Ti Mare basalt, chondrule (CV and CM), and calcium aluminium inclusion (CAI; Type A and B) compositions. For melts of these compositions Ti3+ = Ti4+ at ∼ FMQ-10.8, -9.5, -9.3, -10.6, and -10.2 (∼ IW-7.5, -6.2, -6.0, -7.3, and -6.9), respectively, independent of temperature.
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Nov 2023
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[30309]
Open Access
Abstract: Understanding the effects of high energy neutron damage on REBa2Cu3O$_{7-\delta}$ (REBCO) coated conductor is of vital importance for the design of the magnetic confinement systems for compact nuclear fusion power plants. However, neutron irradiation campaigns can only be carried out in a few facilities, and the experiments are very slow and expensive partly because the samples become radioactive. Ion irradiation provides an easily accessible alternative route to studying the effects of radiation on high temperature superconductors, which not only increases the volume of technical data that can be obtained but also enables more complex experiments such as in situ cryogenic irradiation. The question is, does ion damage offer a good proxy for neutrons? Here we use high energy resolution fluorescence detected x-ray absorption spectroscopy to probe the effects of fast neutron irradiation on the local environment around the copper ions in the REBCO layer of coated conductor tapes. We find that the spectral changes are similar to those induced by helium ion irradiation, suggesting that both projectiles produce the same types of structural defect in the REBCO lattice, although there is some evidence of an additional type of defect present in the sample heavily damaged by He+ ion irradiation. It is also shown that the linear degradation of superconducting transition temperature (Tc) of coated conductors with the calculated number of displacements per atom occurs at the same rate for neutrons and helium ions. Together these results provide new evidence suggesting that helium ions can emulate neutron point defect damage in REBCO high temperature superconductor reasonably well, increasing confidence that helium ions could be used as a useful proxy for neutrons in future experiments.
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Aug 2023
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[23496]
Open Access
Abstract: Vivianite, a hydrated ferrous phosphate [FeII3(PO4)2 · 8 H2O] that forms in oxygen-poor, but Fe2+-rich conditions is important in nutrient cycling in anoxic environments. In natural vivianites, isomorphic substitution of divalent cations for structural Fe(II) are typical. However, anion substitution is rare; in particular, arsenate (AsVO43−) substitution has never been documented in natural vivianites. Only partial substitution has been reported in synthetic analogues, and parasymplesite [FeII3(AsO4)2 · 8 H2O], the arsenic end member of the vivianite mineral group, is found in hydrothermal deposits. In this study, we detail structural changes in synthesised As-vivianites (FeII3[(PO4)1−x(AsO4)x]2 · 8 H2O) with systematically increased degrees of As(V) substitution (0.22 ≤ x ≤ 0.95). As(V) was successfully incorporated into the vivianite crystal structure, creating a homogenous, solid solution between AsVO43− and PO43−. Like both end members, the intermediate As-vivianites crystallised in the monoclinic system (C2/m space group), and retained the platelet crystal habit of As-free vivianite, even at the highest As(V) substitution. This uniform incorporation of As(V), and its replacement of PO43−, provides a potentially stable sink for arsenic in anoxic soils and sediments, and may have implications in ferruginous early Earth oceans.
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Aug 2023
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I18-Microfocus Spectroscopy
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Alexander P.
Morrell
,
Richard A.
Martin
,
Helen M
Roberts
,
Hiram
Castillo-Michel
,
J. Frederick W.
Mosselmans
,
Kalotina
Geraki
,
Adrian T.
Warfield
,
Paul
Lingor
,
Wasif
Qayyum
,
Daniel
Graf
,
Maria
Febbraio
,
Owen
Addison
Diamond Proposal Number(s):
[17638, 23569]
Open Access
Abstract: Exposures to exogenous particles is of increasing concern to human health. Characterising the concentrations, chemical species, distribution, and involvement of the stimulus with the tissue microanatomy is essential in understanding the associated biological response. However, no single imaging technique can interrogate all these features at once which confounds and limits correlative analyses. Developments of synchronous imaging strategies, allowing multiple features to be identified simultaneously, is essential to assess spatial relationships between these key features with greater confidence. Here we present data to first highlight complications of correlative analysis between the tissue microanatomy and elemental composition associated with imaging serial tissue sections. This is achieved by assessing both the cellular and elemental distribution in 3-dimensional space using optical microscopy on serial sections and confocal X-ray fluorescence spectroscopy on bulk samples respectively. We propose a new imaging strategy using lanthanide tagged antibodies with X-ray fluorescence spectroscopy. Using simulations, a series of lanthanide tags were identified as candidate labels for scenarios where tissue sections are imaged. The feasibility and value of the proposed approach is shown where an exposure of Ti was identified concurrently with CD45 positive cells at sub-cellular resolutions. Significant heterogeneity in the distribution of exogenous particles and cells can be present between immediately adjacent serial sections showing clear need of synchronous imaging methods. The proposed approach enables elemental compositions to be correlated with the tissue microanatomy in a highly multiplexed and non-destructive manner at high spatial resolutions with the opportunity for subsequent guided analysis.
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May 2023
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