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Showing 1 to 20 of 125 for “"xas"”.
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XAS studies of metal speciation in hydrothermal fluids
… (0-7.68 m Cl⁻) at 400 and 600 bar. Quantitative XAS data interpretation revealed that Ni(II) chloroaqua complexes undergo a structural transition from octahedral at room temperature to distorted tetrahedral at elevated temperatures. Both heating and an increase in salinity promote the stability …
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Design, Fabrication and Characterization of a GaAs/InxGa1-xAs/GaAs Heterojunction Bipolar Transistor
Designs for PnP GaAs/InxGa1-xAs/GaAs heterojunction bipolar transistors (HBTs) are proposed and simulated with the aid of commercial software. Band diagrams, Gummel plots and common emitter characteristics are shown for the specific case of x=1, x=0.7, and x linearly graded from 0.75 to 0.7. Of the …
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Epitaxial aluminium gates in ultra-shallow GaAs/AlxGa1-xAs heterostructures for low disorder nanoelectronics
… suppression of surface charge in GaAs/Alx Ga1 xAs systems with ultra-shallow conduction channels by using epitaxial aluminium gates grown in the crystal growth system. We grow aluminium gates in the crystal growth chamber and find it prevents the formation of native surface oxides at the …
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Scanning transmission electron microscopy (STEM) and X-ray absorption spectroscopy (XAS) investigations of catalytic systems
… predominantly, X-ray absorption spectroscopy (XAS) and scanning transmission electron microscopy (STEM) or spherical aberration-corrected STEM (Cs-STEM). Although the majority of the work focuses on γ-Al2O3 supported nanoparticles because of their industrial importance for fuel production, …
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Extending first principles spectroscopy to disordered materials: a study on amorphous and crystalline aluminas
… (NMR) and X-ray absorption spectroscopy (XAS) are two locally sensitive techniques that do not rely on periodicity. To compare amorphous models to experiment, it is then necessary to extend first principles calculations of NMR and XAS to amorphous materials. In this thesis, I apply first …
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Mixed As/Sb and tensile strained Ge/InGaAs heterostructures for low-power tunnel field effect transistors
… The mixed arsenide/antimonide (As/Sb) InxGa1-xAs/GaAsySb1-y and Ge/InxGa1-xAs heterostructures allow a wide range of bandgap energies and various band alignments depending on the alloy compositions in the source and channel materials. Band alignments at source/channel heterointerface can be …
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Feasibility of superconductivity in semiconductor superlatices
… (high-Tc) superconductors. A GaAs-A1xGa1-xAs semiconductor structure is proposed which is predicted to superconduct at Tc = 2.0 K and may be analogous to the layered electronic structure of high-Tc superconductors. Formation of an alternating sequence of electron- and hole-populated …
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Tensile-Strained Ge/III-V Heterostructures for Low-Power Nanoelectronic Devices
… such as germanium (Ge) and InxGa1-xAs, enhance the ON-state current and improve the switching behavior of TFET devices, thus making these materials attractive candidates for further study. Moreover, epitaxial growth of Ge on InxGa1-xAs results in tensile stress (ε) within the Ge …
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Microstructure Evolution in Ion -Implanted Aluminum Gallium Arsenide
… microstructures observed in implanted AlxGa1-xAs. An amorphization model based on the physical and thermal properties of AlxGa1-xAs is presented. The variation of the microstructure with Al content is demonstrated to be a function of the distribution of energetic recoils in the material during …
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The femtosecond m-edge approach to the photodynamics of iron(II) complexes
… remained elusive. X-ray absorption spectroscopy (XAS) has long been used to study the electronic structure of transition metal compounds. For 1st-row transition metals, XAS employing soft X-rays (L2,3-edge XAS) or extreme ultraviolet light (XUV, M2,3-edge XAS) is particularly sensitive to the …
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Internal atomic-scale structure and photothermal dynamics of heterostructured nanomaterials
… modes, with X-ray absorption spectroscopy (XAS) as a crucial element-specific technique. Through a combination of optical spectroscopy, electron microscopy, elemental analysis, and the global analysis of the extended X-ray absorption fine structure (EXAFS) spectrum, we show that the intended …
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CONTACT PRESSURE MEASUREMENT
… The ternary semiconductor material A1xGa1-xAs has been known to exhibit piezoresistive behaviour. An investigation was carried out to find out the behaviour of the material and the possibility of configuring it into a contact pressure sensor for the measurement of contact pressure at the …
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OPERANDO X-RAY ABSORPTION SPECTROSCOPY STUDIES OF (PHOTO)ELECTRODE MATERIALS FOR H2 PRODUCTION/CONVERSION
… microscopy (TEM), X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. (2) The electrochemical performance, reaction mechanism, charge transfer kinetics, and overpotential of the synthesized electrodes were rigorously evaluated by cyclic …
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High oxygen permeation rates through poly(dimethyl siloxane) for fuel cells and oxygen reduction reaction mechanistic studies
… electrochemical X-ray Absorption Spectroscopy (XAS) cell for the study of mechanistic details of ORR electrocatalysis on platinum, the most commonly utilized ORR cathode material. The large ORR overpotential on Pt (~0.33 V loss at onset potential) accounts for the majority of polymer electrolyte …
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Developments in the Theory of X-ray Absorption and Compton Scattering.
… approaches for studying x-ray absorption (XAS) and x-ray photoemision (XPS) properties are described by single particle Green’s function theory. In strongly correlated systems, such as transition metal oxides, it is necessary to go beyond single particle treatment in order to reasonably …
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Experimental and theoretical investigation of the electronic structures of ferrocene-peptide conjugates
… is presented. Soft X-ray absorption (XAS) and emission (XES) spectroscopy using synchrotron radiation are used to probe the unoccupied and occupied partial densities of electronic states, respectively. The identities of the finalstate orbitals corresponding to all near-edge features in …
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Untersuchung der Methanoloxidation über Kupfer(poly) mittels Hochdruck-in-situ-Röntgenabsorptionsspektroskopie im weichen Energiebereich von 200 eV bis 1000 eV
… zur in situ Röntgenabsorptionsspektroskopie (XAS) im weichen Energiebereich von 200 eV bis 1000 eV unter Umgebungsbedingungen vorgestellt. Diese Apparatur wurde entwickelt, um oberflächenempfindliche Untersuchungen mit der Totalelektronenausbeutetechnik (TEY) bei Drücken von bis zu 20 mbar und …
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Comparative Analysis and Speciation of Sulfur K, L-edge X-ray Absorption Spectroscopy
… eV) S K, L-edge X-ray absorption spectroscopy (XAS). All the recorded spectra for both K, L-edges were measured in fluorescence yield (TFY) and total electron yield (TEY) and only TEY were considered for the purpose of this study. A direct qualitative approach was used to directly compare the …
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I. Raman scattering and x-ray diffraction study of annealing effects on confined LO and folded LA phonons in GaAs-AlAs superlattices ; II. Picosecond light scattering studies of relaxation and tunneling in GaAs/AlxGa1-xAs mulitple quatum well structures
… and the dynamics of electrons in GaAs/AlxGal-xAs multiple quantum well structures. In our study of the effects of annealing on a short-period GaAs/ AlAs superlattice we have used Raman scattering in conjunction with x-ray diffraction measurements to determine the effects of interface …
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Reliability and Mode Behavior of Aluminum Gallium Arsenide-Gallium Arsenide-Indium Gallium Arsenide Quantum Well Heterostructure Lasers
Data are presented on ten-stripe AlxGa1-xAs-GaAs-In yGa1-yAs quantum well heterostructure edge-emitting lasers showing results of stochastic recoupling of the laser at the Fabry-Perot interface. Scattering by epoxy or oil embedded with Al2O3 polishing compound or 10-mum diameter Al powder results …
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