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30 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I18-Microfocus Spectroscopy	An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash Ilemona C. Okeme , Peter G. Martin , Christopher Jones , Richard A. Crane , Theophilus I. Ojonimi , Konstantin Ignatyev , Thomas B. Scott Spectrochimica Acta Part B: Atomic Spectroscopy DOI: 10.1016/j.sab.2020.105950 Diamond Proposal Number(s): [22876] Show Abstract ▼ Abstract: Fly ash represents a promising alternative source of rare earth elements (REE). However, information on REE containing mineral phases and their association with other fly ash components, vital for REE recovery from fly ash, is currently lacking. Herein, the mass fraction, distribution, crystallography and solid-state chemistry of REE, U and Th in Nigerian simulated fly ash samples were characterised using a range of laboratory and synchrotron x-ray based analytical techniques to underpin future extraction methodologies. Inductively coupled plasma mass spectrometry following full-acid digest of forty-five samples revealed recoverable average total REE content which ranged between 442 mgkg−1and 625 mgkg−1, comprising over 30 wt% of the critical REE Nd, Eu, Tb, Dy, Y and Er. These REE within the fly ash samples were found to be most frequently associated with discrete monazite, xenotime and Y-bearing zircon mineral particles, with the former the most detected, which could be beneficiated through gravity separation. Analysis of monazite particles isolated from the composite samples through a complimentary suite of analytical synchrotron radiation techniques revealed a core-shell pattern, with the shell rich in colocalised Ce, Nd and La, and the core enrich in both U and Th. Ce in monazite was found to exist in a mixed trivalent and tetravalent oxidation state, with the monazite structure amorphized due to the high temperature combustion process. Such results demonstrate the strong co-association and physical distribution of REE, U and Th within monazite in fly ash; knowledge of which can subsequently be used to optimise or develop a more selective, cost-effective and environmentally friendly solvent extraction methodology, by targeting the strongly colocalised and surface bound REE in fly ash monazite particles.	Aug 2020
B22-Multimode InfraRed imaging And Microspectroscopy	Transmission Fourier Transform Infrared (FT-IR) imaging, mapping, and synchrotron scanning microscopy with ZnS hemispheres on living mammalian cells at sub-cellular resolution Ka Lung Andrew Chan , Ali Altharawi , Pedro L. Fale , Cai Li Song , Sergei G. Kazarian , Gianfelice Cinque , Valerie Untereiner , Ganesh Sockalingum Applied Spectroscopy DOI: 10.1177/0003702819898275 Diamond Proposal Number(s): [17501] Show Abstract ▼ Abstract: Fourier transform infrared (FT-IR) spectroscopic imaging and microscopy of single living cells are established label-free technique for the study of cell biology. The constant driver to improve the spatial resolution of the technique is due to the diffraction limit given by IR wavelength making subcellular study challenging. Recently we have reported, with the use of a prototype ZnS transmission cell made of two hemispheres, that the spatial resolution is improved by the factor of the refractive index of ZnS, achieving a λ/2.7 spatial resolution using the synchrotron– IR microscopy with a 36x objective with numerical aperture (NA) of 0.5. To refine and to demonstrate that the ZnS hemisphere transmission device can be translated to standard bench-top FT-IR imaging systems, we have, in this work, modified the device to achieve a more precise path length, which has improved the spectral quality of the living cells, and showed for the first time that the device can be applied to study live cells with three different bench-top FT-IR imaging systems. We applied focal plane array (FPA) imaging, linear array, and a synchrotron single point scanning method and demonstrated that in all cases, subcellular details of individual living cells can be obtained. Results have shown that imaging with the FPA detector can measure the largest area in a given time whilst measurements from the scanning methods produced a smoother image. Synchrotron single point mapping produced the best quality image and has the flexibility to introduce over sampling to produce images of cells with great details, but it is time consuming in scanning mode. In summary, this work has demonstrated that the ZnS hemispheres can be applied in all three spectroscopic approaches to improve the spatial resolution without any modification to the existing microscopes.	Feb 2020
I09-Surface and Interface Structural Analysis	Effective attenuation length of keV photoelectrons in silicon measured by transmission through thin membranes Vladyslav Solokha , Tien-lin Lee , Axel Wilson , Kurt Hingerl , Jorg Zegenhagen Journal Of Electron Spectroscopy And Related Phenomena DOI: 10.1016/j.elspec.2018.03.003 Diamond Proposal Number(s): [15716] Open Access Show Abstract ▼ Abstract: We use 9 nm and 15 nm thin membranes for determining the effective attenuation length of photoelectrons in silicon. One side of silicon membranes was covered with a thin film of aluminium and exposed to X-rays with energies from 3 to 8 keV. We recorded Al 1s and 2s photoelectrons that were (a) emitted from the Al film directly and (b) transmitted through the membranes. With the help of the ratio of both yields, we obtained values for the effective attenuation length (EAL) of electrons with kinetic energies up to 7.9 keV in silicon. The experimentally determined EAL values are smaller than obtained from different predictive equations. Using a power law fit View the MathML sourceEAL(k,p)=kEkinp to the experimental and predicted EAL values we find that mainly different is the pre-factor of the power law, k, while the exponent, i.e. the dependence on kinetic energy Ekin is represented well. Our study underlines the feasibility of using membranes for investigating surfaces under (near) ambient pressure conditions by photoelectron spectroscopy and points out the advantages of employing hard X-rays.	Mar 2018
I06-Nanoscience I10-Beamline for Advanced Dichroism Theoretical Physics	Time-resolved X-ray detected ferromagnetic resonance of spin currents Gerrit Van Der Laan Journal Of Electron Spectroscopy And Related Phenomena 220, 137-146 DOI: 10.1016/j.elspec.2016.12.011 Diamond Proposal Number(s): [10191, 11500, 11501, 13047] Show Abstract ▼ Abstract: X-ray detected ferromagnetic resonance (XFMR) has recently emerged as a powerful synchrotron-radiation-based tool able to study the element-selective magnetization dynamics. Magnetic and chemical contrast in XFMR is obtained by X-ray magnetic circular dichroism (XMCD), while the phase difference between the magnetization precessions is monitored using stroboscopic probing. A unique property of time-resolved XFMR is the visualization of the magnetization precession for each individual layer in a magnetic device. Measurement of the amplitude and phase response of the magnetic layers gives a clear signature of spin-transfer torque (STT) coupling between ferromagnetic layers due to spin pumping.	Oct 2017
I09-Surface and Interface Structural Analysis	Non-dipolar effects in photoelectron-based normal incidence x-ray standing wave experiments Gerben Van Straaten , Markus Franke , Francois . Bocquet , F. Stefan Tautz , Christian Kumpf Journal Of Electron Spectroscopy And Related Phenomena 222, 106-116 DOI: 10.1016/j.elspec.2017.07.007 Diamond Proposal Number(s): [8449, 15122] Show Abstract ▼ Abstract: The normal incidence x-ray standing waves technique is one of the most well-established methods for investigating the geometric structure at interfaces and surfaces. It is able to measure vertical positions and distances of individual atomic species with highest precision (typically <0.02 Å). These data not only yield valuable structural information, but also represent an excellent benchmark for density functional theory and ab initio calculations. Non-dipolar effects are well known to strongly affect the result, in particular when light elements are involved. A correction mechanism for these effects is established, but in its commonly-used form it is based on one essential restriction, namely the assumption of perfect normal incidence of the x-rays with respect to the relevant lattice planes of the crystal. Here, we show that small deviations from normal incidence, as they are unavoidable in typical experimental setups, lead to significant systematic errors in the NIXSW results. The magnitude of this effect depends on the specific conditions in a non-linear way and may reach up to 5%, corresponding to several tenths of an Ångström in the adsorption height. We present a straightforward way of accounting for this effect, and demonstrate that recording the photoelectron yield in an angular-resolved mode is indispensable, since the correction parameters strongly depend on the electron take-off angle.	Jul 2017
B23-Circular Dichroism	The correlation of plasma proteins binding capacity and flavopiridol cellular and clinical trial studies Daniel P. Myatt Biomedical Spectroscopy And Imaging 6, 59 - 73 DOI: 10.3233/BSI-170165 Diamond Proposal Number(s): [1681, 2074] Open Access Show Abstract ▼ Abstract: Previous clinical research has suggested high-affinity binding of flavopiridol (FLAP) to human blood serum proteins, specifically either human serum albumin (HSA) or human alpha-1-acid glycoprotein (hAGP), when compared to fetal bovine serum albumin (BSA) or bovine alpha-1-acid glycoprotein (bAGP) used in pre-clinical assays. This high-affinity binding was suggested as the reason for its poor human clinical trial performance as a treatment for chronic lymphocytic leukaemia (CLL). Using three biophysical techniques, specifically circular dichroism (CD), isothermal calorimetry (ITC) and fluorescence spectroscopy, I show that FLAP does not have an overly high-affinity for either fetal BSA, HSA, bAGP or hAGP. I therefore suggest an alternate hypothesis that models the albumin and alpha-1-acid glycoprotein (AGP) binding sites at the different protein concentrations used in the fetal bovine pre-clinical assay and human physiological conditions. I use analytical ultracentrifugation (AUC) experiments to determine the validity of the theoretical models. The models can also be altered to account for the elevated AGP levels and reduced albumin levels seen in human cancer patients. Major differences in the concentrations of free available FLAP are observed between the fetal bovine pre-clinical model and human physiological conditions. A number of recommendations can therefore be made on how future pre-clinical assay studies should be conducted.	Jun 2017
	In situ X-ray Photoelectron Spectroscopy of Electrochemically Active Solid-Gas and Solid-Liquid Interfaces Axel Knop-gericke , Verena Pfeifer , Juan-jesus Velasco-velez , Travis Jones , Rosa Arrigo , Michael Hävecker , R. Schlögl Journal Of Electron Spectroscopy And Related Phenomena DOI: 10.1016/j.elspec.2017.03.010 Show Abstract ▼ Abstract: In this account the application of synchrotron radiation based X-ray photoelectron spectroscopy (XPS) for the investigation of electrochemically active gas-solid and liquid-solid interfaces will be discussed. The potential of Near Ambient Pressure XPS (NAP-XPS) for the estimation of the electronic surface structure of electrochemically active interfaces will be described by two examples. Thereto the oxygen evolution reaction (OER) over Pt and IrOx anodes will be introduced. In particular the analysis of XP core level spectra of IrOx requires the development of an appropriate fit model. Furthermore the design of reaction cells based on proton exchange membranes (PEM) and on electron transparent graphene membranes, which enables the investigation of liquid-gas and liquid-solid interfaces under electrochemical relevant conditions will be discussed. In the last part of this article a perspective to the EMIL project at the synchrotron radiation facility BESSY will be given. The purpose of this project is the implementation of two new beamlines enabling X-ray photoelectron spectroscopy in the X-ray regime from 80 eV − 8 keV under reaction conditions. The extension to the so called tender X-ray regime will allow the release of higher kinetic energy photoelectrons which have a higher inelastic mean free path compared to photoelectrons excited by soft X-ray radiation and therefore will enable the investigation of solid-liquid interfaces under electrochemical reaction conditions.	Mar 2017
B22-Multimode InfraRed imaging And Microspectroscopy	Detecting nutrient deficiency in plant systems using synchrotron Fourier-transform infrared microspectroscopy Holly J. Butler , Steven Adams , Martin R. Mcainsh , Francis L. Martin Vibrational Spectroscopy DOI: 10.1016/j.vibspec.2017.03.004 Diamond Proposal Number(s): [9755] Show Abstract ▼ Abstract: By 2050, it is estimated that the global population will have surpassed 9 billion people, presenting a significant challenge with regards to food security. In order to provide sufficient quantities of nutritious food in the future, it is necessary to improve agricultural productivity by up to 70%. Nutrient deficiencies are one particular threat to food security that can have a negative impact on crop yield and quality. Currently the standard agricultural approach to prevention is to supply an excess macronutrient fertiliser, such as nitrate or phosphate, during crop production. However, the efficiency of this approach is poor as deficiencies of specific nutrients, such as Ca, are not prevented in this circumstance, and fertiliser use is associated with a host of adverse environmental impacts. Herein, we describe a novel method to detect Ca deficiency using synchrotron radiation-based Fourier-transform infrared (FTIR) microspectroscopy in live and fixed tissue of the model plant Commelina communis, as a precursor to targeted nutrient remediation in the field.	Mar 2017
I18-Microfocus Spectroscopy	Chemical imaging analysis of the brain with X-ray methods Joanna F. Collingwood , Freddy Adams Spectrochimica Acta Part B: Atomic Spectroscopy DOI: 10.1016/j.sab.2017.02.013 Diamond Proposal Number(s): [4911] Show Abstract ▼ Abstract: Cells employ various metal and metalloid ions to augment the structure and the function of proteins and to assist with vital biological processes. In the brain they mediate biochemical processes, and disrupted metabolism of metals may be a contributing factor in neurodegenerative disorders. In this tutorial review we will discuss the particular role of X-ray methods for elemental imaging analysis of accumulated metal species and metal-containing compounds in biological materials, in the context of post-mortem brain tissue. X-rays have the advantage that they have a short wavelength and can penetrate through a thick biological sample. Many of the X-ray microscopy techniques that provide the greatest sensitivity and specificity for trace metal concentrations in biological materials are emerging at synchrotron X-ray facilities. Here, the extremely high flux available across a wide range of soft and hard X-rays, combined with state-of-the-art focusing techniques and ultra-sensitive detectors, makes it viable to undertake direct imaging of a number of elements in brain tissue. The different methods for synchrotron imaging of metals in brain tissues at regional, cellular, and sub-cellular spatial resolution are discussed. Methods covered include X-ray fluorescence for elemental imaging, X-ray absorption spectrometry for speciation imaging, X-ray diffraction for structural imaging, phase contrast for enhanced contrast imaging and scanning transmission X-ray microscopy for spectromicroscopy. Two- and three-dimensional (confocal and tomographic) imaging methods are considered as well as the correlation of X-ray microscopy with other imaging tools.	Feb 2017
B18-Core EXAFS	Facile room temperature deposition of gold nanoparticle-ionic liquid hybrid film on silica substrate S. Krishnamurthy , D. Harikishore Kumar Reddy , G. Sankar , Yeoung-sang Yun Spectrochimica Acta Part A: Molecular And Biomolecular Spectroscopy 170, 48 - 55 DOI: 10.1016/j.saa.2016.07.004 Show Abstract ▼ Abstract: This work presents facile synthesis of gold nanoparticle (Au NP)-ionic liquid hybrid film of < 10 nm by a simple two-step process at room temperature by deposition of Au NPs suspended in 1-hexyl-1methyl-pyrolidinium bromide, on Si (111) substrates. FTIR results demonstrated that ionic liquid properties remain unaltered during and after Au NP synthesis, and even coating on Si (111) substrate. XRD, XPS, and XAS spectral data confirm the presence of Au(0) while EXAFS data indicated the presence of small particles or incomplete surface species. Cross-sectional analysis using FE-SEM and edge length measurement using AFM showed that the film thickness is ca 10 nm.	Dec 2016

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