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Showing 1 to 20 of 23 for “"XAFS"”.
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Developments of time-resolved XAFS spectroscopy techniques - applications in homogeneous catalysis
… mechanisms. In this thesis the application of XAFS spectroscopy in homogeneous catalytic systems is explored. Theory and data-analysis procedures to reliable analyze and interpret the obtained XAFS data, and instrumentation to monitor homogeneous catalytic reactions in situ and in a …
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Spektroskopische Untersuchungen (TRLFS und XAFS) zur Wechselwirkung von dreiwertigen Lanthaniden und Actiniden mit der Mineralphase Calcit
… sowie die Röntgenabsorptionsspektroskopie (EXAFS) eingesetzt. Die untersuchten An(III) bzw. Ln(III) dotierten Calcite wurden in Durchflussexperimenten (unter konstanten Bedingungen) hergestellt. Die TRLFS erlaubt die Charakterisierung des Komplexierungszustandes von An(III) bzw. Ln(III) durch …
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Understanding the origin of the recovery of superconductivity in halogenated YBCO single crystal : atomic structure study
… multiple-edge x-ray absorption fine structure (XAFS) measurements about the Y K, Ba L_3, I L_3, Cu K and Br K-edges at room temperature on brominated (non-brominated) and iodinated (non-iodinated) YBCO single crystals. Our XAFS results at the Br K (brominated) and I L_3 -edges (iodinated) reveal …
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Operando Characterization of Lithium-Ion Batteries using Lab-Scale X-ray Emission/Absorption Spectroscopy
… (XES) and X-ray Absorption Fine Structure (XAFS) perform this role well through the generation/quenching of core holes in the sample. Laboratory-based core hole x-ray spectroscopy techniques have recently gained popularity as they are more accessible and provide energy resolution close to …
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An Investigation into Selenium Geochemistry in Phosphate Mine Soils
… X-ray absorption fine structure (XAFS) spectroscopy for both whole and a sequence of extracted soils. Lastly, competitive adsorption of Se with two dissolved organic carbon (DOC) species, citric and salicylic acid, was examined on an amorphous iron oxide mineral surface. A strong …
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Scattering and Absorption of X-rays by Interstellar Dust
… besonderes Absorptionsmerkmal (die sogenannten XAFS) untersucht, das von den festen Teilchen im interstellaren Medium verursacht wird. Die am meisten absorbierten Quellen erscheinen als die besten Kandidaten fuer eine erflgreiche Erkennung der XAFS. Da der Absorptionsquerschnitt fuer Staub den …
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Geochemical Conditions Affecting Uranium(VI) Fate And Transport In Soil And Groundwater In The Presence Of Phosphate
… probed using X-ray absorption fine-structure: XAFS) spectroscopy for different total U(VI) concentrations over a pH range 4-7 in the absence and presence of phosphate. The structure of precipitated U(VI) fit the meta-autunite group structure. While U(VI) adsorbed as bidentate edge-sharing …
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Festkörperredoxaustausch
… Charakterisierungsmethoden (TPHE, DRIFT, XAFS, XRD, TPAD) konnte nachgewiesen werden, dass der FKRA an Metallen mit niedrigem Schmelzpunkt in Kombination mit einem sehr niedrigen elektrochemischen Potential erfolgt. Die Träger benötigen als hinreichendes Kriterium …
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Spectroscopic and Kinetic Studies of Hydrodenitrogenation and Hydrodesulfurization over Supported Nickel Phosphide (Ni₂P)
… and X-ray absorbance fine structure (XAFS) spectroscopy. In situ FTIR was employed to study the acidity of Ni₂P/SiO₂ and probe the catalytic sites involved in the HDN of pyridine. Transient and steady-state kinetics of a surface intermediate that is formed upon pyridine adsorption and …
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High-throughput synthesis and characterization of vanadium mixed metal oxide pigments using synchroton radiation
… absorption fine structure (XAFS) spectroscopy, solid state UV-Visible and Raman<br/>spectroscopy, Scanning and Transmission electron microscopy (SEM and TEM).<br/><br/>Vanadium mixed metal oxide BiMeVOX with Me = Mo, Cu and Fe, and calcium<br/>pyrovanadate with Me = Pb, Cd, …
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Reactivity and Structure of Supported Nickel Phosphides (Ni₂P) in Deep Hydrodesulfurization Catalysis
… (FTIR) and X-ray absorption fine structure (XAFS) spectroscopy. The use of these techniques allowed better understanding of the nature of the active sites as well as the effect of supports. Activity tests were conducted in the HDS of 4,6-DMDBT and the HDN of quinoline. The performance of the …
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The role of additives in Fischer-Tropsch reactions
… methods such as X-ray Absorption Fine Structure (XAFS) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) and Brunner-Emmett-Taller surface area determination (BET). The characterisation was …
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Effect of ceria and zirconia on nanoparticulate rhodium catalysts
… area measurement, TEM, STEM HAADF, EDX, XPS, and XAFS.<br/>The combination of Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Mass Spectrometry (MS) and Energy Dispersive X-ray Absorption Fine Structure (EDE) techniques in a synchronous, time-resolved manner has been applied …
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Reconstruction of Rhodium Clusters During CO Oxidation and Consequences on The Reaction Mechanism
… (DRIFTS) and X-ray absorption fine structure (XAFS) spectroscopy, is usually implemented as characterization tools. However, understanding the limitation of the characterization tools is crucial to eliminate misleading conclusions. Therefore, the main object of this work is not only to …
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Composites of Spherical Polyelectrolyte Brushes and Nanoparticles – Synthesis, Characterization and Their Use in Catalysis
… TEM (HRTEM) and X-ray absorption fine structure (XAFS) analysis. The qualitative X-ray absorption near-edge structure (XANES) analysis using reference compounds confirmed the crystallographic similarity of the MnOxNP to a c-disordered birnessite. The local structure of the MnOxNP was investigated …
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Characteristics and Mechanisms of Heavy Metal and MTBE Adsorption on Zeolites and Applications in Permeable Reactive Barriers
… entire adsorption process. The synchrotron-based XAFS investigation was combined with batch adsorption tests and micro-structural methods to explore the mechanisms of Pb adsorption onto clinoptilolite and ZSM-5 with or without the presence of MTBE. The batch tests show that ZSM-5 has a low …
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Diluted Magnetic Semiconductor Cobalt and Europium Implanted ZnO Thin Film
… clustering. X-ray absorption fine structure (XAFS) confirms that Eu3+ had substituted for Zn2+ and resided in tetrahedral geometry without changing the wurtzite structure of ZnO host lattice in Zn1-xEuxO; whereas substitutional Co2+ and Co metallic clusters are coexisting in Zn1-xCoxO. But the …
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The development of ceria-based catalysts for automotive after-treatment applications
… were also extensively characterised using XAFS and XPS techniques to understand the effects of the ion beam treatment on the structure, morphology and Pt dispersion of the materials.
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Investigation of accelerated ageing protocols applied to Lean NOx Trap catalysts
… techniques involved were: XRD, XPS, XAFS, ICP and BET. The most significant changes observed were: sulfur poisoning, Pt sintering, ceria sintering and Pd-Pt alloying. Sulfur poisoning was exclusively observed on samples exposed to exhaust gasses. <br/><br/>Chapter III illustrates the …
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Structure Sensitivity in the Subnanometer Regime on Pt and Pd Supported Catalysts
… including x-ray absorption fine structure (XAFS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), diffuse reflectance infrared spectroscopy (DRIFTS), calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the structure of Pt/TiO2 and …
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