TY - JOUR. T1 - Mechanism of ammonia formation on Rh(111) studied by dispersive near-edge X-ray absorption fine structure spectroscopy. AU - Nagasaka, Masanari. AU - Kondoh, Hiroshi. AU - Amemiya, Kenta. AU - Nakai, Ikuyo. AU - Shimada, Toru. AU - Yokota, Reona. AU - Ohta, Toshiaki. PY - 2010/2/11. Y1 - 2010/2/11. N2 - The reaction mechanism of ammonia formation on a Rh(111) surface was investigated by means of dispersive near-edge X-ray absorption fine structure (dispersive-NEXAFS) spectroscopy. Nitrogen-covered Rh(111) surfaces were exposed to gaseous hydrogen (1.0-5.0 × 10-7 Torr) at constant surface temperatures (330-390 K) to form ammonia which desorbs immediately from the surface. Continuous data acquisition of nitrogen K-edge NEXAFS spectra enables us to monitor coverage changes of surface species during the progress of the reaction. The obtained NEXAFS spectra were well reproduced by summation of the standard spectra for N and NH. We found that the NH species, which is considered as a ...

In situ time-resolved X-ray absorption near-edge structure (XANES) and X-ray diffraction (XRD) measurements are applied to track the phase transition processes of LixNi0.5Mn1.5O4, which is one of the most promising positive electrode materials for lithium ion batteries with its high redox potential

The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5{sup ′}-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5{sup ′}-monophosphate, and adenosine 5{sup ′}-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety. ...

TY - JOUR. T1 - An extended x-ray absorption fine structure spectroscopy investigation of cadmium sorption on cryptomelane (KMn8O16). AU - Randall, SR. AU - Sherman, DM. AU - Ragnarsdottir, KV. PY - 1998. Y1 - 1998. M3 - Article (Academic Journal). VL - 151. SP - 95. EP - 106. JO - Chemical Geology. JF - Chemical Geology. SN - 0009-2541. ER - ...

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TY - JOUR. T1 - Local structure of LiCoO 2 nanoparticles studied by Co K-edge x-ray absorption spectroscopy. AU - Maugeri, L.. AU - Iadecola, A.. AU - Joseph, B.. AU - Simonelli, L.. AU - Olivi, L.. AU - Okubo, M.. AU - Honma, I.. AU - Wadati, H.. AU - Mizokawa, T.. AU - Saini, N. L.. PY - 2012/8/22. Y1 - 2012/8/22. N2 - We have studied the local structure of LiCoO 2 nanoparticles by Co K-edge x-ray absorption spectroscopy as a function of particle size. Extended x-ray absorption fine structure data reveal substantial changes in the near neighbor distances and the associated mean square relative displacements with decreasing particle size. X-ray absorption near edge structure spectra show clear local geometrical changes with decreasing particle size, similar to those that appear in the charging (delithiation) process. The results suggest that the LiCoO 2 nanoparticles are characterized by a large atomic disorder confined to the Co-O octahedra, similar to the distortions generated during the ...

Extended X-ray absorption fine structure and X-ray absorption near-edge structure techniques were used to study in detail the structural characteristics of FeCo-Al2O3 nanocomposite xerogels and aerogels. The fort-nation of bcc FeCo alloy, which cannot be assessed unambiguously by X-ray diffraction, dispersed within the alumina matrix was evidenced in the final samples obtained by heat treatment at 800 degrees C in reducing atmosphere. Aerogel samples reduced below 800 degrees C still present a fraction of oxidized metal together with the bcc alloy. The investigation of the xerogels and aerogels calcined at increasing temperature indicates that Fe(111) and Co(II) ions are present and they are located in the tetrahedral sites of the spinel structure of the matrix (gamma-Al2O3); moreover, the precursor of the spinel is more ordered in the aerogel sample than the xerogel sample. ...

Heptacene was generated by surface-assisted didecarbonylation of an α-diketone precursor on a Ag(111) surface. Monitoring of the surface reaction and characterization of the adsorbed heptacene was performed with scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT) calculations. The surface-assisted formation of heptacene occurs around 460 K. Both the heptacene and the precursor molecules are oriented along the high-symmetry directions of the (111) surface and their molecular π systems face towards the substrate. The interaction with the Ag(111) substrate is not laterally uniform, but appears to be strongest on the central part of the molecule, in line with the expectations from Clars rule. In the STM images, heptacene shows a dumbbell shape, which may correspond to the substantial out-of-plane deformations of heptacene on Ag(111). As revealed by DFT, the center of the ...

x-ray magnetic circular dichroism (XMCD) x-ray x ray detector x ray centers in hyderabad x pole xpert dance pole x pole x frame banner stand x banner stands x banner stand x back chair x X-ray navigation X-ray microtomography X-ray emission spectroscopy X-ray emission X-ray cross section X-ray absorption spectroscopy X-ray absorption near-edge structure X-ray Physics X-ray Microscopy X-ray Diffractometry (PXRD) X-ray CT X-ray Binaries X-ray Analysis X-ray Absorption Fine Structure (XAFS) X-pinch X-machines X-linked mental retardation X-inactivation X-band Radar X-Ray Optics X-Ray Fluorescence (XRF) Spectroscopy X-Ray Bursters X-Ray Absorption Spectroscopy (in Materials C X-Men (Marvel Comics) X-Group X-FEM X ray Inspection X ray Imaging X ray Fluorescence X ray Film X ray Equipment X ray Diffraction X ray Computed Tomography X ray Absorption X chromosome inactivation X chromosomal Inactivation X Ray Photoelectron Spectroscopy X Ray Photoelectron X Ray Microscope X Ray Market X Ray Devices X Ray

The one-dimensional (1D) TiO2 nanotubes (NTs) and their derivatives have been extensively studied due to their wide applications, such as photocatalysts, solar cell, paints and so on. Since TiO2 has a wide band gap (~3.0 eV), its photo-absorption as the photocatalyst only occurs in the UV region that wastes mostly solar energy. Therefore, the solution to higher photocatalytic efficiency has been sought for some time. This thesis presents a study of the size-dependent phase transitions of TiO2 NTs using synchrotron-based X-ray techniques. The chemical environment including local symmetry and the luminescence origin of the TiO2 NTs can be tracked by X-ray absorption near-edge structures (XANES) and X-ray excited optical luminescence (XEOL) technique. As a result, the anatase-to-rutile transition highly depended on the sizes of NTs with the same annealing treatment. Additionally, the shortest NTs require a lower temperature to start the amorphous-to-anatase transition.

TY - JOUR. T1 - Anatase-TiO2 nanomaterials. T2 - Morphological/size dependence of the crystallization and phase behavior phenomena. AU - Fernández-García, Marcos. AU - Wang, Xianqin. AU - Belver, Carolina. AU - Hanson, Jonathan C.. AU - Rodriguez, José A.. PY - 2007/1/18. Y1 - 2007/1/18. N2 - Nanoparticulated TiO2 materials with anatase structure were synthesized by using a microemulsion method. Three different syntheses with varying surfactant-to-water molar ratio (CD) were used to obtain amorphous solid precipitates at room temperature. The structural characteristics of these solid precursors were studied by using X-ray absorption structure (X-ray absorption near-edge structure and extended X-ray absorption fine structure) and Raman spectroscopies, which showed that all lack 3D (tridimensional) order but contain a different degree of 2D-confmed connectivity. While heating such solid precursors under dry air, marked differences appeared in the phase behavior; the onset temperature for ...

In situ X-ray absorption spectroscopy has afforded detailed structural and electronic characterization of a newly developed stabilized Pt-skin/PtCo alloy nanoparticle catalyst for CO-tolerant H2 oxidation. The X-ray absorption near-edge structure (XANES) results show the significant effects of H and CO adsorption o

Sulfur and iron concentrations in wood from three 17th century shipwrecks in the Baltic Sea, the Ghost wreck, the Crown and the Sword, were obtained by X-ray fluorescence (XRF) scanning. In near anaerobic environments symbiotic microorganisms degrade waterlogged wood, reduce sulfate and promote accumulation of low-valent sulfur compounds, as previously found for the famous wrecks of the Vasa and Mary Rose. Sulfur K-edge X-ray absorption near-edge structure (XANES) analyses of Ghost wreck wood show that organic thiols and disulfides dominate, together with elemental sulfur probably generated by sulfur-oxidizing Beggiatoa bacteria. Iron sulfides were not detected, consistent with the relatively low iron concentration in the wood. In a museum climate with high atmospheric humidity oxidation processes, especially of iron sulfides formed in the presence of corroding iron, may induce post-conservation wood degradation. Subject to more general confirmation by further analyses no severe conservation ...

The safety and feasibility of industrial electrochemical production of sodium chlorate, an important chemical in the pulp and paper industry, depend on the selectivity of the electrode processes. The cathodic reduction of anodic products is sufficiently suppressed in the current technology by the addition of chromium(VI) to the electrolyte, but due to the high toxicity of these compounds, alternative pathways are required to maintain high process efficiency. In this paper, we evaluate the electrochemical hydrogen evolution reaction kinetics and selectivity on thermally formed manganese oxide-coated titanium electrodes in hypochlorite and chlorate solutions. The morphology and phase composition of manganese oxide layers were varied via alteration of the annealing temperature during synthesis, as confirmed by scanning electron microscopy, X-ray diffraction, synchrotron radiation X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy measurements. As shown in ...

Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms ...

Bioaccessibility tests and mineralogical analyses were performed on arsenic-contaminated tailings and soils from gold mine districts of Nova Scotia, Canada, to examine the links between soil composition, mineralogy, and arsenic bioaccessibility. Arsenic bioaccessibility ranges from 0.1% to 49%. A weak correlation was observed between total and bioaccessible arsenic concentrations, and the arsenic bioaccessibility was not correlated with other elements. Bulk X-ray absorption near-edge structure analysis shows arsenic in these near-surface samples is mainly in the pentavalent form, indicating that most of the arsenopyrite (As1−) originally present in the tailings and soils has been oxidized during weathering reactions. Detailed mineralogical analyses of individual samples have identified up to seven arsenic species, the relative proportions of which appear to affect arsenic bioaccessibility. The highest arsenic bioaccessibility (up to 49%) is associated with the presence of calcium−iron ...

The valence states of Mn in mixed-valent layer and tunnel structure manganese dioxides (MnO2), usually referred to as phyllomanganates and tectomanganates, can be measured by X-ray absorption near-edge structure (XANES) spectroscopy with a precision and accuracy that are difficult to estimate owing to the paucity of well-characterized standards. A compilation of the Mn K-edge XANES spectra of most naturally occurring manganates, synthetic analogs of known structure and chemical composition, and pure-valence phase species is presented and made available as an open source. We intend this compilation to serve as a basis for the spectroscopic determination of the fractions of the Mn 2+, 3+, and 4+ valences in mixed-valent manganates and phase mixtures. The XANES derivatives of tectomanganates and phyllomanganates with no or little Mn3+ in the MnO2 layer exhibit intensities, shapes, and relative energy positions of the main features characteristics of a particular valence composition. For these ...

SEE PDF Full Length Article Writers: Ariadne C. Catto, Luís F. da Silva, Maria Inês B. Bernardi, Sandrine Bernardini, Khalifa Aguir, Elson Longo, and Valmor R. Mastelaro. Keywords: cobalt; gas sensor; ozone; XANES spectroscopy; XPS; zinc oxide. Abstract: A detailed study of the structural, surface, and gas-sensing properties of nanostructured CoxZn1-xO films is presented. X-ray diffraction (XRD) analysis revealed a decrease in the crystallization degree with increasing Co content. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopies (XPS) revealed that the Co2+ ions preferentially occupied the Zn2+ sites and that the oxygen vacancy concentration increased as the amount of cobalt increased. Electrical measurements showed that the Co dopants not only enhanced the sensor response at low ozone levels (ca. 42 ppb) but also led to a decrease in the operating temperature and improved selectivity. The enhancement in the gas-sensing properties was attributed to the ...

X-ray absorption spectroscopy (XAS). -EXAFS (extended X-ray absorption fine structure) for determination of metal site fine structures (metal-metal and metal-ligand distances at ~0.02 Å resolution, chemical nature and number of metal ligands).. -XANES (X-ray absorption near edge structure) for determination of metal oxidation state and site geometry. ...read more, for example here or here X-ray absorption linear dichroism spectroscopy (XALDS) for determination of orientations of interatomic vectors within, for example, the protein matrix, in crystals and partially oriented systems (such as proteins in biological membranes). ...read more, for example here or here. XAS under elevated gas pressure ...read more, for example here. X-ray emission spectroscopy (XES) for probing metal oxidation state, spin state, site geometry, electronic configuration, ligand structures, etc. ...read more, for example here or here. Time-resolved XAS/XES to follow structural changes and redox transitions at metal ...

Fujisawa et al. studied the electronic structures of CuFeS2 and CuAl0.9Fe0.1S2 by observing the phenomenon and analyzing the data of the states of Fe and Cu, and the valence-band of unit cell. The S 3p-Fe 3d bonding is found covalent base on the obvious tail of DAPT the XPS spectra of Cu 2p and S 2p [43]. Mikhlin et al. compared and analyzed the abraded chalcopyrite. and bornite in a vacuum chamber by X-ray absorption near-edge structure (XALES) to exam the electronic structure [44]. The result showed the Cu L3-edge had a strong pre-edge peak and a small post-edge peak, the Fe L2,3-edge energy was consistent with the Fe2+ oxidation state and S L-edge spectra was clearly observed [44]. It is widely accepted that the Neel temperature of CuFeS2 is extremely high, at 823 K [45] and [46]. Edelbro et al. proposed that the energy bands (−13.8 to 12.5 eV), which is lower than Fermi level, selleck chemical is similar to that of sphalerite. Woolley et al. demonstrated that, at temperature above 50 K and ...

Polarization-dependent grazing incidence X-ray Absorption Spectroscopy (XAS) measurements were completed on oriented single crystals of magnesite [MgCO3] and brucite [Mg(OH)2] reacted with aqueous uranyl chloride above and below the solubility boundaries of schoepite (500, 50, and 5 ppm) at pH 8.3 and at ambient (PCO2 = 10-3.5) or reduced partial pressures of carbon dioxide (PCO2 = 10-4.5). X-ray Absorption Near Edge Structure (XANES) spectra show a striking polarization dependence ( = 0° and  = 90° relative to the polarization plane of the incident beam) and consistently demonstrated that the uranyl molecule was preferentially oriented with its Oaxial=U(VI)=Oaxial linkage at high angles (60-80º) to both magnesite () and brucite (0001). Extended X-ray Absorption Fine Structure (EXAFS) analysis shows that the effective number of U(VI) axial oxygens is the most strongly affected fitting parameter as a function of polarization. Furthermore, axial tilt in the surface thin films (thickness ...

TY - JOUR. T1 - Local fivefold symmetry in liquid and undercooled Ni probed by x-ray absorption spectroscopy and computer simulations. AU - Di Cicco, A.. AU - Iesari, F.. AU - De Panfilis, S.. AU - Celino, M.. AU - Giusepponi, S.. AU - Filipponi, A.. PY - 2014/2/12. Y1 - 2014/2/12. N2 - Presence and significance of fivefold configurations in liquid metals are investigated by combining x-ray absorption spectroscopy and computer simulations (molecular dynamics and reverse Monte Carlo) in liquid and undercooled liquid nickel. We show that icosahedral short-range ordering (ISRO), probed by common-neighbor (CNA) and spherical invariant (Wî6) analysis, involves a limited fraction (14-18% in undercooled nickel for different structural models) of local atomic configurations. The emerging picture for the liquid structure is that of a mixture of nearly icosahedral structures embedded in a disordered network mainly composed of fragments of highly distorted icosahedra (40-45% of the total), structures ...

2010.12.13 The reseach article Noradrenaline and a Thiol Analogue on Gold Surfaces: an IRAS, XPS and NEXAFS Study. was published in Journal of Physical Chemistry C. Self-assembled monolayers and multilayers of a noradrenaline analogue (Nor-Pt) on gold substrates as well as multilayers of noradrenaline have been investigated by means of the molecular orientation, the molecule−surface interaction, the molecular composition and the functional group availability for further biointeraction processes, using X-ray photoelectron spectroscopy (XPS), infrared reflection−absorption spectroscopy (IRAS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy ...

Macromolecular arrays containing Zn-diethynylporphyrin coordinated to platinum tethers were studied using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the N K-edge. Porphin (Pf), 2,8,12,18-tetraethyl-5,15-diethynyl-3,7,13,17-tetramethylporphyrin (PfNH) and 2,8,12,18-tetraethyl-5,15-diethynyl-3,7,13,17-tetramethylporphyrinatozinc(II) (Zn-Pf2), have been taken as experimental models. The resonances assignment is supported by static-exchange (STEX) calculations for the porphin (Pf) and Zn-porphin (Zn-Pf1) molecules. By calculation, four pi* resonances occur for porphin (Pf) and two for Zn-Pf1. Experimentally we detect four resonances for porphin and PfNH, and two for the Zn-complexed ones. They can be assigned to core excitations to a couple of energy split pi* orbitals for each not equivalent N atom. Our calculations justify the observed low pi* intensity as due to an extended delocalization of the pi* orbitals. The NEXAFS investigations on platinum complex/Zn-porphyrinato ...

We have calculated the N 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of nitrogen-doped monolayer graphene (NG) using density functional theory (DFT) with the equivalent core hole approximation. The hexavacancy (6V) defect and its dependence on the nitrogen-doping concentration have been analyzed in detail via both N 1s -, pi* and N 1s -, sigma* transitions. The NEXAFS spectra are sensitive to the doping concentration of N in the pi* region: diluted doping weakens the main pi* peak and smears the oscillations in this region. The vacancy defect leads to a red-shift in both the pi and sigma spectra. A pyridinic nitrogen at the 6V defect center exhibits a sharp pi* peak at 398.4 eV, which agrees well with the experimental pre-edge structure at 398.6 eV. The sigma* peak is split in two, which can serve as the fingerprint to reveal the nature of the defect. A structural change from pyridinic to pyrrolic NG results in a distinctive difference in the spectral shape. The ground-state ...

Controlling molecular orientation is of great importance in organic thin films due to the fact that the fundamental properties of functional nanomaterials depend on molecular orientation at the nanoscale. However, controlling molecular orientation cannot be achieved without having an extensive understanding about the controlling factors in the organic film growth processes. Most previous studies have been devoted to monolayer structures. The structure of multilayer films has not been well investigated. This study was performed using a phenomenological approach, in which the morphology and orientation of n-alkane thin films were studied as a function of substrate identity, interface treatment, substrate temperature and deposition rate. The experimental techniques that were used include IR-spectroscopy, polarized optical microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray microscopy. The kinetic and thermodynamic factors that govern the orientation of organic ...

High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.. ...

The magnetic properties of the bis(phthalocyaninato)terbium complexes [Tb{Pc(SR)8}2] (1) containing eight beta-positioned long-chain alkylthio substituents SR (a: R=n-C8H17, b: R=n-C12H25) were studied by SQUID measurements, which revealed that both compounds are single-molecule magnets with an effective energy barrier for spin reversal significantly higher than that found for pristine bis(phthalocyaninato)terbium [Tb(Pc)2]. Thin films on gold were fabricated from 1?a and 1?b by chemisorption from solution and were characterised by near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS). In the case of 1?a, atomic force microscopy (AFM) was used in addition. The results are in accord with the formation of self-assembled monolayers which contain the macrocyclic rings mainly in an approximately horizontal orientation. The chemisorption is primarily due to the peripheral SR substituents, giving rise to coordinatively bound thioether units, whose alkyl chains ...

Abstract: Amorphous, low-porosity carbon spheres on the order of a few micrometers in size were prepared by carbonization of squalane (C30H62) in supercritical CO2 at 823 K. The spheres were characterized and used as catalysts supports for Pd. Near-edge X-ray absorption fine structure studies of the spheres revealed sp2 and sp3 hybridized carbon. To activate carbons for interaction with a metal precursor, often oxidative treatment of a support is needed. We showed that boiling of the obtained spheres in 28 wt % HNO3 did not affect the shape and bulk structure of the spheres, but led to creation of a considerable amount of surface oxygen-containing functional groups and increase of the content of sp2 hybridized carbon on the surface. This carbon was seen by scanning transmission electron microscopy in the form of waving graphene flakes. The H/C atomic ratio in the spheres was relatively high (0.4) and did not change with the HNO3 treatment. Palladium was deposited by impregnation with Pd acetate ...

The increasing uses of rare-earth-doped upconversion nanoparticles (UCNPs) have obviously caused many concerns about their potential toxicology on live organisms. In addition, the UCNPs can be released into the environment, then transported into edible crop plants, and finally entered into food chain. Here, the soybean is chosen as a model plant to study the subchronic phytotoxicity, translocation, and biotransformation of NaYF4 UCNPs. The incubation with UCNPs at a relative low concentration of 10 mu g mL(-1) leads to growth promotion for the roots and stems, while concentration exceeding 50 mu g mL(-1) brings concentration-dependent inhibition. Upconversion luminescence imaging and scanning electron microscope characterization show that the UCNPs can be absorbed by roots and parts of the adsorbed UCNPs are then transported through vessels to stems and leaves. The near-edge X-ray absorption fine structure spectra reveal that the adsorbed NaYF4 nanoparticles are relatively stable during a 10 d ...

The Near Edge X-ray Absorption Fine Structure (NEXAFS) experimental stations uses a tunable, focused monochromatic beam of soft X-rays (0.1 keV to 2.2 keV) t

The electronic properties of Au crystal and nano Au have been investigated by theory and experiment. Molecularly capped nano-Au was synthesized using the two-phase method. Au nano-particles have been characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). They retain the fcc crystal structure. Their sizes have been determined to be in a range from 5.5 nm to 1.7 nm. The L3 X-ray Absorption Near Edge Structure (XANES) of nano-Au and Au foil have been recorded using synchrotron radiation, and examined by theoretical calculation [1] based on the first principles [2,3]. Both theory and experiment show that the nano-Au particles have essentially all the Au L3 XANES features of bulk Au in the near edge region with less pronounced resonance peaks. It is also shown that nano Au exhibits lower 4f binding energy than bulk Au in good agreement with quantum confined Au systems reported previously [3,4].

A broad range of chemical reactions are triggered by the absorption of light. Examples include photosynthesis and charge transfer in semiconductors and molecules. Electronic dynamics which evolve on the few femtosecond to attosecond timescale are expected to play an important role in these processes. We aim to investigate these dynamics with transient X-ray absorption near edge structure (XANES) spectroscopy. XANES spectroscopy uses resonant excitation of particular atoms in a molecule to provide a highly localised probe of electronic structure. By employing attosecond soft x-ray pulses generated via high harmonic generation for XANES spectroscopy this atomic scale spatial resolution can in principle be combined with the attosecond temporal resolution required for tracking electronic dynamics. I shall present development of a beamline for transient XANES spectroscopy and progress towards visible pump, soft x-ray probe experiments in the organic polymer poly(hexylthiophene ...

Micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy has been used by several recent studies to determine the oxidation state and coordination of iron in silicate glasses. Here, we present new results from Fe μ-XANES analyses on a set of 19 Fe-bearing felsic glasses and 9 basaltic glasses with known, independently determined, iron oxidation state. Some of these glasses were measured previously via Fe XANES (7 rhyolitic, 9 basaltic glasses; Cottrell et al. 2009), while most felsic reference glasses (12) were analyzed for the first time. The main purpose of this study was to understand how small changes in glass composition, especially at the evolved end of silicate melt compositions occurring in nature, may affect a calibration of the Fe μ-XANES method.. We performed Fe μ-XANES analyses at different synchrotron radiation sources [Advanced Photon Source (APS), Argonne, U.S.A., and Angströmquelle Karlsruhe (ANKA), Germany] and compared our results to existing calibrations obtained ...

X-ray Absorption Spectroscopy (XAS) is a technique to analyze the elemental properties of a material. It can also allow one to understand the chemistry on a molecular level and whether the material is amorphous or crystalline. XAS has dignificant advantages compared to other methods since it is element specific, no high vacuum required, and no specific sample preparation is required. The XAS experiments can be either static (before and/or after reactions) or dynamic (in situ reactions) while the materials can be in solid, liquid, or gaseous states. ...

Ecosystems throughout the world are experiencing significant biogeochemical perturbation from anthropogenic activities. As one example, manganese (Mn) is enriched in surface soils at the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) in Pennsylvania due to past atmospheric inputs from industrial sources. At the SSHCZO, large quantities of Mn that are leached from soil components into solution are taken up by vegetation each year; as a result, only relatively small quantities of Mn are transferred from hillslopes into the stream. Here, we combined mass balance models at the containerized seedling (mesocosm) and pedon-scales with synchrotron-source spectroscopies (X-ray fluorescence and X-ray absorption near edge structure) to examine Mn geochemistry in the soil-plant system and the impact of vegetation on Mn transport in forested catchments.. Manganese uptake into vegetation exceeded Mn losses in soil leachate, and net Mn loss from soils decreased in the presence of vegetation due to ...

We propose an asymmetric bilayer structure in which the magnetic remanence (MR) is controlled by the in-plane strain of the top NiFe2O4 (NFO) layer epitaxially constrained by the bottom Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) substrate. In this asymmetric structure, an electric-field-induced giant piezoelectric strain from the bottom PMN-PT layer is effectively transferred to the top NFO layer. We have shown that the room-temperature magnetic remanence (MR) of the 100-nm-thick NFO layer is enhanced by 46% when an electric-field-induced in-plane compressive strain is about -0.1%. Synchrotron x-ray absorption near edge structure study supports a scenario of the cation-charge redistribution between Ni2+ and Fe3+ ions under the condition of an electric-field-induced in-plane compressive strain ...

Copper powder was introduced into the lithium sulfur battery system to capture intermediate polysulfides and Cu xS (x = 1 or 2) species was generated depending on the chain length of polysulfides. This phenomenon was verified by X-ray absorption near edge structure technique. The results indicated that copper can be oxidized to CuS by Li 2S x (x ≥ 6), and a mixture of Cu 2S and CuS was obtained when x ranges from 3 to 6. While Cu 2S is eventually formed in the presence of Li 2S 3. After several cycles activation, the polysulfide-shuttle effect and self-discharge phenomenon which hinder the application of lithium sulfur batteries are found nearly eliminated Further experiments demonstrated that in the case of Cu 2S generation, a high specific sulfur capacity of 1300 mAh g -1 could be delivered, corresponding to 77.6% sulfur utilization, while the Coulombic efficiency approximates around 100%. As a result, self-discharge experiment further demonstrated that polysulfides almost disappear in the ...

Hexane selenol (CH3(CH2)(5)SeH) was adsorbed from gas phase in ultra-high vacuum on polycrystalline Cu and studied with synchrotron radiation based photoelectron spectroscopy (PES) and Near edge X-ray absorption fine structure spectroscopy (NEXAFS). Adsorption was done on a bare copper surface at room temperature (RT), on a thin oxide on Cu at room temperature, and on a thin layer of water on Cu at 140 K.. ...

TY - JOUR. T1 - Application of polarised ultra-soft X-Ray absorption spectroscopy to the characterisation of the structure of molecular interfaces.. AU - Hastie, G P. AU - Johnstone, J. AU - Roberts, K J. AU - Fisher, D. PY - 1996. Y1 - 1996. M3 - Article. VL - 166. SP - 67. EP - 71. JO - Journal of Crystal Growth. JF - Journal of Crystal Growth. SN - 0022-0248. ER - ...

The DXAS beamline is an experimental station dedicated to dispersive x-ray absorption spectroscopy (acronym for DXAS) techniques, in the hard x-ray energy range (5 to 14 keV). The peculiarity of this beamline is the capability to collect absorption spectra over an extended range of photon energies without any mechanical movement of its optical elements. The DXAS is especially suited for detecting weak signals in XANES (X-ray Absorption Near-Edge Spectroscopy) and XMCD (X-ray Magnetic Circular Dichroism) experiments and for tracking time-dependent evolution of chemical reactions.. DXAS is installed on a 1.67T bending-magnet source, and it was opened to users in 2005. The beamline is comprised by the synchrotron light source, a vertically focusing bendable mirror, a bent crystal polychromator, and an area detector. The beam path over the optical elements starts when it hits the bendable mirror, used for vertical focusing as well as harmonic rejection. Then the light beam impinges onto a ...

Dive into the research topics of In situ electron yield detection of X-ray absorption fine structure of electrodes continuously emersed from electrolyte solutions. Together they form a unique fingerprint. ...

A means for intracavity sum frequency generation is described in which a er operates simultaneously, cw, at two wavelengths where the net gain at one wavelength is substantially lower than that at the other. The optical alignment of the resonator provides a region where both fundamental wavelengths are overlapped, and another region where both feedback paths are spatially distinct. An active feedback mirror is located in the path of the lower net gain laser transition to provide optical amplification at that wavelength. The laser resonator further contains a sum frequency generating crystal for intracavity sum frequency generation of the two fundamental wavelengths. The sum frequency generating crystal is placed near a laser resonator cavity mode waist in the region where both wavelengths are spatially superimposed, producing the sum frequency of the two wavelengths. An intracavity polarization rotator provides the appropriate orientation of the polarization of the two fundamental wavelengths in the

Very small, thioglycerol (TG)-capped CdS nanoparticles were synthesized by a wet chemical technique and investigated in the framework of this thesis. Also glutathione-capped particles were investigated for a comparison of the capping agents. High-resolution photoelectron spectroscopy using high-brilliance synchrotron radiation was applied as the major tool for the characterization of these particles. Additionally, the particles were investigated with UV-VIS absorption spectroscopy, XPS using a laboratory source, valence band photoemission spectroscopy (VBPES), near-edge x-ray absorption spectroscopy (NEXAFS), and micro-Raman spectroscopy to address various aspects of the particles. In the beginning, an overview on size quantization effects is given to create a theoretical background behind the work presented in this thesis. Furthermore, an overview of various conventional techniques for size determination is presented. Exact information about size, shape and size distribution of nanoparticles is ...

As shown in Figure 122, the subnanometric Pt species are finely dispersed in the MCM-22 crystallites. The size of the Pt species and their location in the crystallites was determined with the help of aberration-corrected electron microscopy. The Pt atoms and clusters are located both in the surface cups of MCM-22 and within the zeolite framework. In particular, a large proportion of the subnanometric Pt species are located in the internal space of the structure.. A [email protected] sample has been studied at beamline BM23 using X-ray absorption spectroscopy (XAS) to examine the local environment of Pt and to estimate the coordination number of Pt species. The Fourier transform of extended X-ray absorption fine structure (EXAFS) spectra of [email protected] and the Pt and PtO2 reference are shown in Figure 123a. Considering the first shell, the [email protected] spectrum is dominated by a peak centred around 2.65 Å with a smaller contribution at 2.08 Å (both distances are not phase corrected). Comparing with ...

Nanoscale zerovalent iron (NZVI) that was aged in simulated groundwater was evaluated for alterations in composition and speciation over 6 months to understand the possible transformations NZVI could undergo in natural waters. NZVI was exposed to 10 mN of various common groundwater anions (Cl-, NO3-, SO42-, HPO42-, and HCO3-) or to dissolved oxygen (saturated, similar to 9 mg/L). Fresh and exposed NZVI samples, along with Fe-oxide model compounds, were then analyzed using synchrotron radiation X-ray absorption spectroscopy (XAS) to yield both relative oxidation state, using the X-ray absorption near edge structure (XANES), and quantitative speciation information regarding the types and proportions of mineral species present, from analysis of the extended X-ray absorption fine structure (EXAFS). Over 1 month of aging the dissolved anions inhibited the oxidation of the NZVI to varying degrees. Aging for 6 months, however, resulted in average oxidation states that were similar to each other ...

Graphene-based materials have been studied in a wide range of applications including catalysis due to the outstanding electronic, thermal, and mechanical properties. The unprecedented features of graphene-based catalysts, which are believed to be responsible for their superior performance, have been characterized by many techniques. In this article, we comprehensively summarized the characterization methods covering bulk and surface structure analysis, chemisorption ability determination, and reaction mechanism investigation. We reviewed the advantages/disadvantages of different techniques including Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), X-Ray diffraction (XRD), X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (XAFS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high

TY - JOUR. T1 - Electronic properties of hybridized poly (3, 4-ethylenedioxythiophene). T2 - Polystyrene sulfonate with surface-capped CdSe nanocrystals. AU - Wang, Seok Joo. AU - Park, Hyung Ho. PY - 2009/2/9. Y1 - 2009/2/9. N2 - The chemical state and electronic properties of hybrid material based on poly (3, 4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and pyridine-capped CdSe nanocrystals have been investigated using photoemission spectroscopy, near-edge x-ray absorption fine structure, and ultraviolet photoelectron spectroscopy. With a high dipole moment as well as high physical momentum, CdSe nanocrystals hindered the rearrangement of PEDOT:PSS and induced PSS-rich surface during film formation. Thus, the work function value was decreased by dedoping of PEDOT or charge localization in PEDOT. Through heat treatment, the behavior of π - π transition in C 1s and the work function value was nearly restored, gradually; these mean recovery of electrostatic bonding nature ...

The electronic structure of copper sulfides was studied using X-ray absorption at Cu K and L-2,L-3 and S L-2,L-3 edges and X-ray emission spectroscopy at S L-2,L-3 thresholds. The experimental data were compared with results of local density approximation calculations taking into account the calculated valence band contributions and core-level chemical shifts between inequivalent sites. The presence of divalent Cu was detected in CuS with X-ray absorption spectroscopy in the high-energy-resolution fluorescence detection (HERFD) mode. The S L-2,L-3 emission spectrum of CuS was found to be significantly broader than that of Cu2S due to contributions from inequivalent S sites. This difference in the spectral width was used to distinguish between sulfide species formed on the Cu foil exposed to Na2S solutions. The Cu-S interaction processes for Cu films of different thicknesses exposed to Na2S solutions were monitored in situ using X-ray absorption spectroscopy in the HERFD mode at the Cu K edge. It ...

FAME, the French Absorption spectroscopy beamline in Material and Environmental science, is dedicated to X-ray absorption spectroscopy. FAME covers a wide variety of scientific fields (materials science, biophysics, chemistry) but focuses mainly in geochemical sciences where, in most cases, the probed elements are highly diluted.. FAME being a bending magnet beamline, the optical elements have been designed in order firstly to maximize the photon flux on the sample and secondly to optimize the beamline stability and reduce the non-statistical noise (Proux et al. Journal of Synchrotron Radiation 13 (2006) 59-68). Moreover, for an optimal acquisition of XAS spectra on diluted elements, the intense x-ray beam on the sample needs to be associated with a highly sensitive detection system: fluorescence detection is achieved with a 30-element Canberra Ge solid state detector.. Opened to users since 2002, the beamline offers several sample environments, either to improve the measurements (helium ...

Aqueous gallium(III) citrate complexes have been studied in the 10(-2) M concentration range with extended X-ray absorption fine structure (EXAFS) and FTIR techniques. From EXAFS data, one mononuclear and one oligomeric species were identified at different Ga(III) to citrate ratios. The first shell of the mononuclear complex was found to be distorted, with average Ga-O bond lengths of 1.95 and 2.06 Angstrom, in agreement with the solid-state structure of Ga(Cit)(2)(3-) (Cit = citrate). Also the oligomeric species was found to have a distorted first shell, with average Ga-O bond lengths of 1.95 and 2.04 Angstrom. This complex was found to contain two Ga-Ga distances at 3.03 and 3.56 Angstrom, typical for edge and corner sharing GaO6 octahedra, respectively. The gallium(III) and aluminum(III) citrate systems were compared by means of FTIR, and were found to be analogous. The IR results suggest that the bond lengths derived from EXAFS for the 1:2 gallium(III) citrate complex also provide a good ...

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The principal method of probing the structure of these films was the non-linear optical technique of Sum Frequency Generation (SFG). The experimental techniques used in this work are first introduced together with a theoretical description of SFG. There then follows an overview which describes semiconductor nanoparticle monolayers and the application of SFG to them. The work was subsequently extended to the investigation of multilayers of semiconductor nanoparticles incorporated within fatty acid films. Whilst SFG of monolayers is well understood SFG of multilayer films is not and most of this dissertation has been devoted to providing a systematic description of SFG of multilayer films adsorbed onto both metal and dielectric substrates. The observed multilayer SFG spectrum is shown to be a superposition of SFG signals coming from the surface layer, in contact with air, and the lowermost layer, in contact with the substrate. The SFG spectrum is a simple numerical addition of the two signals when ...

As essential media currently used in several technological applications, the accurate molecular level description of ionic liquids (ILs) at the gas-liquid interface is of utmost importance. The inherently surface-sensitive technique, sum frequency generation (SFG) spectroscopy, in combination with bulk-sensitive vibrational spectroscopic techniques such as FTIR and Raman, have been used in this report to characterize the surface of cyano-containing ILs, such as [BMIM][SCN], [BMIM][DCA], [BMIM][TCM], and [EMIM][TCB] at the gas-liquid interface. By structural variation of the anion while keeping the cation constant, emphasis on the molecular arrangement of the anion at the gas-liquid interface was reported. Vibrational modes seen in the C-H stretching region revealed the presence of the cation with an orientation independent of the type of anion. A similar arrangement at the surface as reported in previous studies was found. All three anions of varying symmetry, namely, [DCA]- (C2v), [TCM]-(D3h), ...

The zinc contents of fragments of Escherichia coli glutamyl-tRNA synthetase, as well as the conservation of the CYC sequence only in zinc-containing glutamyl-tRNA synthetases, suggested that the 98CYCX24-CRHSHEHHADDEPC138 includes some or all residues involved in binding its zinc atom (Liu, J., Lin, S.-X., Blochet, J.-E., Pézolet, M., and Lapointe, J. (1993) Biochemistry 32, 11390-11396). Extended x-ray absorption fine structure (EXAFS) shows that this zinc atom has a four-coordinate non-planar coordination environment with 3 sulfur and 1 nitrogen atoms with bond lengths, respectively, 2.37 +/- 0.02 A and 2.01 +/- 0.02 A, presumably belonging to 3 cysteine residues and 1 histidine residue. Conservative replacement of each histidine and cysteine residue of the 98C-138C segment, respectively, with glutamine (Q) and serine (S), yields variants H129Q, H131Q, H132Q, and C138S (which sustain the growth at 42 degrees C of E. coli JP1449, whose glutamyl-tRNA synthetase is thermosensitive) and C98S, C100S,

Methods Products formed in the reaction between glucose and methionine or its metabolites were analysed in vitro using gas chromatography. Flatus samples from patients with colon cancer and exhaled air samples from patients with lung cancer were analysed using near-edge x-ray fine adsorption structure spectroscopy and compared with those from healthy individuals. The tumour proliferation rates of mice into which HT29 human colon cancer cells had been implanted were compared with those of mice in which the cancer cells were surrounded by sodium hyaluronate gel to prevent diffusion of gaseous material into the healthy cells. ...

High quality rutile Ti1-xSnxO2 nanofilms were successfully grown in a layer-by-layer mode at a moderately low temperature of 400 °C using pulsed laser deposition (PLD). High solid solubility of up to x = 0.216 has been achieved in the Ti1-xSnxO2 films despite theoretical prediction by Density functional theory (DFT) of large formation energy (∼5.64 eV) required for the substitutional alloy to exist at such high Sn concentration. The resultant films have smooth interfaces and step-terraced surfaces with well controlled stoichiometry and are optically transparent. Sn L3-edge Extended X-ray absorption fine structure (EXAFS) reveals the substitution of Sn4+ in the Ti4+ lattice sites of TiO2. The lattice spacing along [110] increases linearly with increment in x due to substitution of Sn4+ ions in the Ti lattice sites of the Ti1-xSnxO2 films. X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering (RBS) show that Sn is uniformly distributed on the surface and in the bulk of the films. ...

Over the last few months, Renishaw engineers and beamline scientists from the Swiss Norwegian beamlines (SNBL) have developed novel Raman probes to advance cutting-edge Synchrotron research. Wouter van Beek and a team of scientists working at SNBL, use simultaneous X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), Raman, and mass spectroscopies (MS), to monitor the kinetics of catalytic reactions insitu.

The chemical composition of functionalized supports is an important parameter that determines their performance in a broad range of applications, e.g. for immobilizing molecular machines. Pyridine-functionalized surfaces, for instance, are often used for the growth of SurMOF. In this article, a critical analysis of XPS (X-ray photoelectron spectroscopy) and NEXAFS (near edge X-ray absorption fine structure) data for pyridine-functionalized surfaces is presented in order to compile correlations that have been indiscernible before. Samples with aromatic backbones are compared to samples with aliphatic backbones. Furthermore, the pyridine head-groups are compared to terpyridine head-groups where the functional groups are diluted by unfunctionalized monolayer molecules to ensure well-ordered monolayers. Oxidation during ageing of the surfaces in air is also addressed. Moreover, the addressability of the samples for the deposition of metal ions and supramolecules is investigated and the samples are ...

TY - JOUR. T1 - The role of in situ generated nano-sized metal particles on the coulombic efficiency of MGeO3 (M = Cu, Fe, and Co) electrodes. AU - Kim, Chang H.. AU - Jung, Yoon S.. AU - Lee, Kyu T.. AU - Ku, Jun H.. AU - Oh, Seung M.. N1 - Funding Information: This work was supported by WCU program through KOSEF funded by the Ministry of Education, Science and Technology (400-2008-0230). The authors also wish to acknowledge the Research Center for Energy Conversion and Storage for financial support, and the Pohang Light Source (PLS) for the XAS measurements.. PY - 2009/7/15. Y1 - 2009/7/15. N2 - To improve the coulombic efficiency of GeO2 electrode, a Cu-containing ternary metal oxide (CuGeO3) was prepared and the electrochemical behavior of Cu component was studied. The GeO2 electrode shows a low coulombic efficiency in the first cycle (43%), which is mainly caused by a poor Ge oxidation kinetics (Ge + 2Li2O → GeO2 + 2Li+ + 2e-). The X-ray absorption spectroscopy (XAS) data illustrate that ...

The CAT end station of the CAT-ACT beamline at ANKA is dedicated to catalytic research using X-ray spectroscopic techniques. It will be operated by the Grunwaldt group at the Institute for Chemical Technology and Polymer Chemistry (http://www.itcp.kit.edu/grunwaldt/) and the Institute of Catalysis Research and Technology (http://www.ikft.kit.edu/234.php).. Synchrotron radiation based techniques have evolved as key speciation methods in catalysis research, especially with respect to in-situ and in-operando X-ray based characterization techniques as a basis for a rational design of heterogeneous catalysts. Knowledge of oxidation state and coordination environment of the catalytically active centers, nanoparticle morphology etc. contributed significantly to a deeper understanding of heterogeneously catalyzed reactions and serves today as a basis for the design of new catalysts and for first-principles kinetic modeling. The beamline design places emphasis on in situ X-ray Absorption Spectroscopy ...

The frontier electronic structures of Ru(tcterpy)(NCS)3 [black dye (BD)] and Ru(dcbpy)2(NCS)2 (N719) have been investigated by photoelectron spectroscopy (PES), X-ray absorption spectroscopy (XAS) and resonant photoelectron spectroscopy (RPES). N1s XAS has been used to probe the nitrogen contribution in the unoccupied density of states, and PES, together with RPES over the N1s edge, has been used to delineate the character of the occupied density of states. The experimental findings of the frontier electron structure are compared to calculations of the partial density of states for the nitrogens in the different ligands (NCS and terpyridine/bipyridine) and for Ru4d. The result indicates large similarities between the two complexes. Specifically, the valence level spectra show two well separated structures at low binding energy. The experimental results indicate that the outermost structure in the valence region largely has a Ru4d character but with a substantial character also from the NCS ...

In this PhD thesis a new experimental approach has been introduced to shed fundamental insight in the architecture and molecular transport barriers of large zeolite crystals. More specifically, we have investigated diffusion limitation in large as-prepared and dealuminated zeolite crystals of AFI and MFI topology by using a combination of ... read more the template removal method with UV-Vis, confocal fluorescence and synchrotron-based IR micro-spectroscopy. Furthermore, a thorough comprehension of the internal architecture and related intergrowth phenomena was obtained through employment of focused ion beam milling - electron backscattered diffraction and electron tomography, atomic force microscopy and X-ray absorption spectroscopy. The goal of this correlative characterization approach was threefold: (1) resolving the intergrowth structure; (2) relating the examined structures to the crystal growth mechanism and (3) understanding the diffusion limiting behavior of the related intracrystalline ...

X-ray Research on Short-lived Isotope Provides New Possibilities for Cancer Treatment - Scientists Improve Understanding of Mysterious Actinium. Excerpted from August 22, 2016 SLAC News Feature. A recent paper published in Nature Communications reveals insights about the element actinium that could support new classes of anticancer drugs. A team of researchers from the Los Alamos National Laboratory has conducted x-ray absorption fine structure experiments on SSRLs Beam Line 11-2 to characterize the molecular and electronic structure, including chemical bonds in actinium compounds.. Using synchrotron-based tools to obtain a better understanding of the structure of Actinium-225, for example, looks promising. It has a relatively short half-life (10 days) and emits powerful alpha particles as it decays to stable bismuth. This makes it a perfect candidate for a novel cancer treatment technique called targeted-alpha therapy, where alpha emissions from radioisotopes destroy malignant cells while ...

Institute of Materials Structure ScienceThe Institute of Materials Structure Science (IMSS), which is affiliated to KEK acting as an Inter-University Research Institute Corporation, promotes interdisciplinary and complimentary use of four types of quantum beams, synchrotron radiation (SR), neutron, muon and positron, in materials and life sciences research. The successful candidate will become an assistant professor of Electronic Structure Group of the Photon Factory (PF), and will play a role in promoting surface and interface sciences using soft X-ray magnetic circular dichroism and soft X-ray absorption spectroscopy, and in developing experimental techniques using soft X-ray. He/she will also be expected to take the responsibilities of operation and maintenance of the related beamlines and experimental apparatuses as well as to promote active user programs of the PF including industrial applications ...

Woolery G.L.; Powers L.; Winkler M.; Solomon E.I.; Spiro T.G., 1984: Extended x ray absorption fine structure studies of bi nuclear copper site of oxy hemo cyanin deoxy hemo cyanin metaquo hemo cyanin met fluoro hemo cyanin and met azido hemo cyanin from arthropods and mollusks

Plant performance is, at least partly, linked to the location of roots with respect to soil structure features and the micro-environment surrounding roots. Measurements of root distributions from intact samples, using optical microscopy and field tracings have been partially successful but are imprecise and labour-intensive. Theoretically, X-ray computed micro-tomography represents an ideal solution for non-invasive imaging of plant roots and soil structure. However, before it becomes fast enough and affordable or easily accessible, there is still a need for a diagnostic tool to investigate root/soil interplay. Here, a method for detection of undisturbed plant roots and their immediate physical environment is presented. X-ray absorption and phase contrast imaging are combined to produce projection images of soil sections from which root distributions and soil structure can be analyzed. The clarity of roots on the X-ray film is sufficient to allow manual tracing on an acetate sheet fixed over the ...

Noethnitzer Str. 40, 01187 Dresden, Germany.. Research Interests:. 1) low-dimensional and geometrically frustrated magnetic systems such as the hexagonal perovskite Ca3Co2O6 and isostructural (Sr,Ca)3ABO6 showing unconventional magnetic structure with strange magnetization jumps, reminiscent of Quantum Tunneling of Magnetization (QTM), and large thermoelectric power and magnetoresistance.. 2) high-Tc superconductive materials and related intermetallic systems. 3) metal-insulating transition in highly correlated systems. Experimental techniques employed:. 1) Powder samples synthesis in furnace under high-pure Argon and Oxygen atmosphere. 2) Single crystal growth using flux method. 3) X-ray absorption spectroscopy (EXAFS and XANES). 4) High resolution powder x-ray and neutron diffraction (Rietveld analysis). 5) Single crystal x-ray and neutron diffraction. 6) Magnetic X-ray scattering. 7) Characterisation of samples at low temperature using a range of techniques including transport, magnetic, ...

3. Antibiotics That Act on Cell Wall Biosynthesis B 43 O R1 S N H O N R2 COO- Category 1. First Generation R1 Cephalothin O S Cephazolin R2 O N N N N N N S S 2. Second Generation Cefamandole N N N N S OH Cefuroxime O O N O O Cefoxitin O S NH2 O 3. Third Generation N Cefotaxime H2N O S N N Ceftriaxone H2N S S N N O N O N OH N Ceftazidime H2N +N S N 4. 18 Continued. This has led to multiple waves of semisynthetic ␤-lactams over the 50 years of their clinical use. Scholar and Pratt (2000) note five categories of penicillins (Fig. Second Generation Cefamandole N N N N S OH Cefuroxime O O N O O Cefoxitin O S NH2 O 3. Third Generation N Cefotaxime H2N O S N N Ceftriaxone H2N S S N N O N O N OH N Ceftazidime H2N +N S N 4. 18 Continued. This has led to multiple waves of semisynthetic ␤-lactams over the 50 years of their clinical use. Scholar and Pratt (2000) note five categories of penicillins (Fig. 18A) based on narrow- versus broad-spectrum activities and whether there is antipseudomonal activity. ...

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Electrochemical conversion of CO2 into liquid fuels, powered by renewable electricity, offers one means to address the need for the storage of intermittent renewable energy. Here we present a cooperative catalyst design of molecule-metal catalyst interfaces with the goal of producing a reaction-intermediate-rich local environment, which improves the electrosynthesis of ethanol from CO2 and H2O. We implement the strategy by functionalizing the copper surface with a family of porphyrin-based metallic complexes that catalyse CO2 to CO. Using density functional theory calculations, and in situ Raman and operando X-ray absorption spectroscopies, we find that the high concentration of local CO facilitates carbon-carbon coupling and steers the reaction pathway towards ethanol. We report a CO2-to-ethanol Faradaic efficiency of 41% and a partial current density of 124 mA cm−2 at −0.82 V versus the reversible hydrogen electrode. We integrate the catalyst into a membrane electrode assembly-based system and

PREFACE. 1. FUNDAMENTALS OF SPECTROSCOPY.. Introduction.. Quantum Mechanics.. Particle in a Box.. Properties of Waves.. References.. Problems.. 2. X-RAY CRYSTALLOGRAPHY.. Introduction.. Scattering of X Rays by a Crystal.. Structure Determination.. Neutron Diffraction.. Nucleic Acid Structure.. Protein Structure.. Enzyme Catalysis.. References.. Problems.. 3. ELECTRONIC SPECTRA.. Introduction.. Absorption Spectra.. Ultraviolet Spectra of Proteins.. Nucleic Acid Spectra.. Prosthetic Groups.. Difference Spectroscopy.. X-Ray Absorption Spectroscopy.. Fluorescence and Phosphorescence.. RecBCD: Helicase Activity Monitored by Fluorescence.. Fluorescence Energy Transfer: A Molecular Ruler.. Application of Energy Transfer to Biological Systems.. Dihydrofolate Reductase .. References .. Problems.. 4. CIRCULAR DICHROISM, OPTICAL ROTARY DISPERSION, AND FLUORESCENCE POLARIZATION.. Introduction.. Optical Rotary Dispersion.. Circular Dichroism.. Optical Rotary Dispersion and Circular Dichroism of ...

X-ray absorption spectroscopy investigations on radioactive matter using MARS beamline at SOLEIL synchrotron Isabelle LLorens, Pier Lorenzo Solari, Bruno Sitaud, René Bes, Sebastiano Cammelli, Hervé Hermange, Guillaume Othmane, Samir Safi, Philippe Moisy, Sandrine Wahu, Carole Bresson, Michel L. Schlegel, Denis Menut, Jean-Luc Bechade, Philippe Martin, Jean-Louis Hazemann, Olivier Proux, Christophe Den Auwer Radiochim. Acta (2014), 102, 957-972 ...

A systematic X-ray absorption spectroscopy investigation of the local coordination in gallium nanostructures has been performed as a function of temperature and particle size. It is shown that the nanostructure strongly affects the polymorphism of solid gallium and the (meta)stability range of the liquid phase (in agreement with previous works) and that the surface tension acts in the same direction as hydrostatic pressure in stabilizing the Ga solid phases. The effect of surface free energy is first to favor the metallic arrangement of the δ phase and then to stabilize a liquid-like phase based on dimeric molecules even at 90 K. The Ga−Ga distance in the dimers is lower in the liquid phase than in the α solid. The experimental results are discussed in comparison with molecular dynamic calculations to assess the presence of covalent character of the dimeric Ga2 units in liquid nanostructured gallium ...

The interaction of guest Pt(II) ions with UiO-66-X (X = NH₂, H, NO₂, OMe, F) series metal-organic frameworks (MOFs) in aqueous solution was investigated using in situ X-ray absorption spectroscopy. All of these MOFs were found to be able to coordinate with Pt(II) ions. The Pt(II) ions in UiO-66-X MOFs generally coordinate with 1.6-2.4 Cl and 1.4-2.4 N or O atoms. We also studied the time evolution ...

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Journal de Physique IV, Journal de Physique Archives représente une mine d informations facile à consulter sur la manière dont la physique a été publiée depuis 1872.

O Misoprostol (nome comercial Cytotec) não tem mais sua venda permitida nas farmácias brasileiras, a única forma de conseguir o princípio ativo legalmente no Brasil é através dos hospitais em procedimentos autorizados judicialmente.. Desta forma, pode-se entender que todo Cytotec vendido no Brasil se dá de forma ilegal, contrabandeado do Paraguay na maioria das vezes sendo incerto saber se a procedência do medicamento é confiável ou não. Não há qualquer certeza se é ou não produto de falsificação ou adulteração.. Na maioria das vezes criminosos anunciam a venda deste medicamento em sites online porém o fazem apenas para aplicar golpes nas mulheres desesperadas que estão correndo atrás do famoso Cytotec. Nós, obviamente não recomendados a compra deste medicamento destas pessoas, pois certamente você estará correndo risco de ter seu dinheiro levado embora sem qualquer satisfação ou de estar tomando algum medicamento que não se sabe exatamente o que é.. O único site ...

95. C. Lambertz, N. Leidel, K. Havelius, P. Chernev, J. Noth, M. Winkler, T. Happe, M. Haumann, O2 reactions at the six-iron active site (H-cluster) of [FeFe]-hydrogenase. J. Biol. Chem. 286, 40614-40623 (2011). 94. N. Planas, L. Vigara, C. Cady, P. Miro, P. Huang, L. Hammarström, S. Styring, N. Leidel, H. Dau, M. Haumann, L. Gagliardi, C. J. Cramer, A. Llobet, Electronic structure of oxidized complexes derived from cis-[RuII(bpy)2(H2O)2]2+ and its photoisomerization mechanism. Inorg. Chem. 50, 11134-11142 (2011). 93. P. P. Samuel, A. Döring, S. Horn, K. Havelius, S. Reschke, L. Leimkühler, M. Haumann, C. Schulzke, A crystallographic and Mo K-edge XAS study of molybdenum-oxo bis-, mono-, and non-dithiolene complexes: first-sphere coordination and non-innocence of ligands. Eur. J. Inorg. Chem. 28, 4387-4399 (2011). 92. J. Fritsch, S. Löscher, O. Sanganas, E. Siebert, I. Zebger, M. Ludwig, M. Stein, A. De Lacey, H. Dau, B. Friedrich, O. Lenz, M. Haumann, NiFe and FeS cofactors in ...

Não eu não voltei para o Cá Aqui. Na verdade, nem sei se quero voltar a escrever. Perdi o rumo. Mais uma vez. Perdi o gosto pela escrita. Meu trabalho tirou todo o prazer que sentia ao ver um arquivo do word aberto em branco bem na minha frente. Mas você não pode deixar que isso influencie tanto? Jura? Então me ensina como faz? Me ensina como é que separamos a vida pessoal da profissional se eu sou uma só? Se você, que lê o Cá Aqui, sabe de uma forma, uma resposta ou alguma técnica, passe adiante. Aqui fica o meu lamento, a pouca vontade, o cansaço demasiado e a raiva repreendida de quem, um dia, achou que poderia escrever por liberdade de criar e de se expressar. Não, eu não posso. Essa á a razão de tamanho desgosto. Por isso, me ausento do blog cada vez mais sem saber ao certo que rumo tomar - como se as escolhas estivessem por milhares... ...

RESUMO A erupção fixa por drogas é uma reação de hipersensibilidade a medicamento não imediata, caracterizada por placas eritematosas ou violáceas, arredondadas, recorrentes, de bordas bem definidas e que aparecem sempre na mesma localização cada vez que o medicamento culpado é administrado. A prática habitual é evitar a droga envolvida e utilizar um medicamento estruturalmente diferente. Contudo, há situações em que não há terapêutica segura e eficaz. Em tais situações, a dessensibilização é a única opção. Descrevemos o caso de um paciente que apresentou erupção fixa por drogas por sulfametoxazol-trimetoprim, tendo sido submetido à dessensibilização com sucesso, mas necessitou repetição do procedimento duas vezes, por recidiva da reação após reintrodução inadvertida em dose plena. Em reação de hipersensibilidade a medicamento não imediata, a indicação é controversa e não há padronização técnica. Além disso, não se conhece o tempo durante o qual essa

FMS1205P - FS: Nanoworld and Synchrotron Radiation. The essence of nanoworld, i.e. nanoscience and technology, is the ability to understand and manipulate matter at the atomic level. Structures and electronic and magnetic structures behave differently when their dimensions are reduced to the range of between one and a few hundred nanometres (1 nanometre = 10-9 metre). They exhibit novel and much-improved mechanical, electrical, optical, chemical and biological properties, due entirely to their nanoscopic size. The nanoworld is therefore an exciting new realm that brings together the traditional disciplines of physics, chemistry, materials science, biology and engineering. To understand the nanoworld, we will introduce basic and advance spectroscopy and scattering synchrotron-based techniques such as x-ray absorption, x-ray magnetic circular dichroism, resonant soft x-ray scattering, xray photoemission spectroscopy, ultraviolet photoemission spectroscopy, angular-resolved photoemission spectroscopy and x

We have the pleasure to announce the upcoming workshop on Total Absorption Spectroscopy: present and near future, to be held at IFIC, Valencia (Spain) from December-16th to December-19th, 2019. This workshop aims to bring together the present and prospective TAS community to review the present status of the different TAS detectors (Lucrecia, DTAS & Rocinante) at the different facilities (ISOLDE, RIKEN, FAIR, JYFL...), as well as discuss the near-future experimental programme, future plans and ideas.. A session of the workshop will be devoted to instrumentation and analysis methods, within the NUSPIN working group on High-Efficiency and Fast Timing Scintillators, and is partially funded by the NUSPIN network in the framework of ENSAR2 (HORIZON2020).. ...

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