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Showing 1 to 19 of 19 for “"NEXAFS"”.
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Systematic Investigation of Intermolecular Interactions in NEXAFS Spectroscopy
Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy can be used to study molecular packing and order in organic materials, but only if the spectroscopic effects of intermolecular interactions are well understood. This work aims to contribute to an improved general understanding of the …
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High-resolution investigation of the electronic structure of organic thin films
… (PES) und Röntgenabsorptionsspektroskopie (NEXAFS) mit höchster Energieauflösung angewandt. Zusätzlich wurden ab initio Rechnungen zur theoretischen Simulation von NEXAFS Spektren durchgeführt. Hauptsächlich wurden dünne, vakuumsublimierte Filme aromatischer Modellmoleküle mit …
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Investigation of Size Specific Fe2O3 nanoparticles: Towards Single Nanoparticle Resolved Spectro-ptychography
… on Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, which provides elemental and chemical sensitivity. In this thesis, NEXAFS spectro-ptychography was used to obtain the Fe L2,3 NEXAFS absorption and phase spectra. The phase signal is theoretically related to the absorption …
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Simulationen von Röntgenabsorptionsprozessen zur Charakterisierung von Systemen in kondensierter Phase
… Genauer gesagt, werden Nahkantenabsorptions- (NEXAFS) sowie Röntgenphotoelektronenspektren (XPS) berechnet. In beiden Fällen wird ein Röntgenphoton von einem molekularen System absorbiert. Aufgrund der hohen Photonenenergie wird ein stark gebundenes kernnahes Elektron angeregt. Bei der XPS …
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Structure and Ozone Decomposition Reactivity of Supported Manganese Oxide Catalysts
… edge x-ray absorption fine structure (EXAFS and NEXAFS) showed that the manganese oxide was highly dispersed on the surface of the supports. EXAFS spectra suggest that the manganese active centers on all of the surfaces were surrounded by five oxygen atoms. These metal centers were of a …
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Effects of Biosolids on Carbon Sequestration and Nitrogen Cycling
… (1s) near edge x-ray absorption fine structure (NEXAFS) spectroscopic techniques; and 3) to compare biosolids types and tillage practices on short-term N availability in the Coastal Plain soils. Biosolids led to C accumulation in the soil surface (< 15 cm) after long-time application in both …
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Self-assembly of amino acids on noble metal surfaces : morphological, chemical and electronic control of matter at the nanoscale
… and near-edge x-ray absorption fine structure (NEXAFS) in ultrahigh vacuum (UHV). On Ag(111), methionine self-assembles into supramolecular chains following the <110> substrate axis, forming regular nanogratings with tunable periodicity. Within the nanowires, a zwitterionic dimerization scheme …
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Characterization of 2-methyl-8-quinolinolato gallium (Iii) chelates
… and emission), thermal and X-ray absorption (NEXAFS) study of gallium (III) bis(2-methyl-8-quinolinolato) carboxylate (2Meq2GaOR) chelates, where OR = acetato (OAc), trifluoroacetato (OTF) and dimethylpropianato (ODMP). These materials are compared with aluminum (III) tris(8-quinolinolato) …
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Soil Organic Nitrogen - Investigation of Soil Amino Acids and Proteinaceous Compounds
… X-ray Adsorption Fine Structure Spectroscopy (NEXAFS) techniques. Specific aims of this study were: 1) to assess potentially bioavailable pool of proteinaceous compounds and the immediately bioavailable pool of free amino acids in surface and subsurface soils of various ecosystems; 2) to …
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Trägereinfluss bei Vanadiumoxid-Katalysatoren zur selektiven Oxidation kurzkettiger Alkane
… ("BET"), XRD, FTIR-, UV/Vis-, Raman- und NEXAFS-Spektroskopie, TGA, TEM und SEM, XRF) wurde angewendet, um die Topologie der Vanadiumoxid-Titanoxid-Oberflächenstrukturen sowie die molekulare Struktur der Vanadiumcluster aufzuklären und ihren Einfluss auf die Ligandeneffekte der oxidativen …
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Uncovering molecular orientation and morphology at biotic/abiotic interface for peptide-based graphene sensors
… X-ray absorption fine structure spectroscopy (NEXAFS) as the primary investigation tool, atomic-level information was obtained about the orientation of the peptide backbones in relation to the graphene surface upon the VOC binding. At the same time, changes in morphology were assessed through …
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The adsorption of organic molecules on metal and semiconductor surfaces
… LEED, AES, TPD and synchrotron-based NIXSW and NEXAFS techniques. It was found that the coadsorption of CO does not induce an ordering of the disordered chemisorbed thiophene layer, in contrast to the behaviour of related benzene coadsorption systems where CO induces ordering of benzene …
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Landscape and environmental controls on soil organic matter decomposability in the High Arctic
… and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy to explore how variability in vegetation and soil moisture across the High Arctic landscape influences soil organic carbon (SOC). My results demonstrate that vegetation type significantly influences the size of labile and more …
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Catalytic Decomposition of a Perfluorinated Carbon Proxy Using Alumina-based Catalysts
… proportion between strong and weak acid sites (NEXAFS). Surface analysis methods were deployed to determine the phases present in the catalyst (XRD). Quantitative acid site calculations used thermogravimetric analysis (TGA) and back-titration methods. Potential catalysts were then tested to …
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Preparation and Reactivity of Niobium-Containing Hydrotreating Catalysts
… and near-edge X-ray absorption fine structure (NEXAFS). It was found that the electronic properties of the oxycarbide were modified by the interaction with the Al₂O₃ support, and that most of the oxygen atoms were associated with the niobium rather than the molybdenum atom. All of the …
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EXPLORING THE ROLE OF METAL VARIABILITY IN MOFS USING SYNCHROTRON RADIATION TECHNIQUES
… X-ray absorption fine structure spectroscopy (AP-NEXAFS) and in situ CO-dosed IR spectroscopy, the role of crystal size in determining the distribution of Cu(I) / Cu(II) species and the kinetics of defect formation under thermal activation is investigated. In following chapters, the presented work …
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Diffraction and Spectroscopy of Marine Calcite Biominerals: Insights into Structure and Geochemistry
… The near edge X-ray absorption fine structure (NEXAFS) spectra at the Na-edge do not appear consistent with Na directly substituting for Ca within the calcite test of A. lessonii. Observations may suggest that Na is incorporated in two distinct chemical environments, with both an ordered and …
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Switching of surface composition and morphology of binary polymer brushes
Switching of surface composition and morphology of binary polymer brushes in response to changes in solvent selectivity, heating above glass transition temperatures, and contact with a rubbery stamp was studied. The binary brushes: polystyrene/poly(2-vinyl pyridine) (PS/P2VP), …
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Electronic properties of metal-organic and organic-organic interfaces studied by photoemission and photoabsorption spectroscopy
In this work systematic studies of the organic semiconductor CuPc have been presented. In general the investigation can be devided in three parts. In the first one we have studied the electronic structure of clean CuPc thin film. The next two parts are devoted to organic-organic and metal–organic …