Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"Local density of states"”.
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Fundamental limits to local density of states in absorptive system
… responses such as absorption, scattering and local density of states (LDOS) are proposed given intrinsic material losses by Owen, etc. The absorption and scattering limits are validated in Owen's work while the LDOS of common structures fall short of the limits. To validate those theoretical …
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Light-matter interaction in silicon nanophotonic structures
… devices. At first, spectroscopic investigation of energy transfer among Er ions and Si-nanoparticles for optical amplification has been reported. Successively, light propagation in dielectric resonator and waveguides has been addressed, in particular considering photon Local Density of States …
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Character of the Electronic States Near the Metal -Insulator Transition in Gallium Manganese Arsenide
The character of electronic states near the Mott-Anderson metal-insulator transition in the ferromagnetic semiconductor Ga1-xMn xAs is studied by cross sectional scanning tunneling microscopy. 200nm thick samples grown by MBE at UCSB with doping levels from 1.5%, close the metal-insulator …
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Electronic band structure of III-V quantum dots using tight-binding and the k.p approximation
… dot by reconstructing an effective continuum local density of states using FEM solutions to the Schr{\""o}dinger equation. The local density of states predicted by the tight-binding model is shown to compare qualitatively to the continuum reconstructed LDOS. The local charge density between …
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Character of the electronic states near the metal-insulator transition in Gallium Manganese Arsenide
The character of electronic states near the Mott-Anderson metal-insulator transition in the ferromagnetic semiconductor Ga1-xMnxAs is studied by cross sectional scanning tunneling microscopy. 200nm thick samples grown by MBE at UCSB with doping levels from 1.5%, close the metal-insulator …
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Electrochemical and NMR Studies of Fuel Cell Catalysts and Carbon Monoxide Surface Diffusion
Surface diffusion of CO adsorbed on Pt nanoparticle catalysts was measured at the solid/liquid interface at and near room temperature, 253 K--293K, by using electrochemical nuclear magnetic resonance (EC-NMR) spectroscopy and a spin labeling pulse sequence. 2H NMR data indicate that the electrolyte …
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A computational electromagnetic framework for waveguide quantum electrodynamics
… respectively) problems is presented. The essence of this framework is to use the dyadic Green's function (DGF) to obtain the local density of states (LDOS) and radiative shift of a two-level system (TLS) embedded in an arbitrary electromagnetic continuum. The dressed states of the system are also …
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Modeling of fluids and waves with analytics and numerics
… instabilities in concentric cylindrical flows of N fluids with arbitrary viscosities, thicknesses, densities, and surface tensions in both the Stokes regime and for the full Navier-Stokes problem. The resulting mathematical model, based on linear-stability analysis, can quickly predict the …
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Scanning tunneling microscopy and spectroscopy of nanometer scale metallic features on silicon surfaces
Nanometer scale metals are of great interest due to their potential applications in the future of molecular/atomic scale devices. For example, nanometer scale metal contacts on semiconducting single-walled carbon nanotubes (SWNTs) can determine the transport performance of SWNT based field effect …
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Scanning tunneling microscopy characterization and metallic nanocontacts for atomically precise graphene nanoribbons
… Once the ribbons are synthesized, confirmation of their geometries and investigating their electronic properties are essential for further implementation in devices. This dissertation addresses investigations of three different solution-synthesized atomically precise GNRs by scanning tunneling …
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Topics in theory of superconductivity
… parts on three different topics in theory of superconductivity. In the first part a theory of nonlocal electrodynamics of unconventional superconductors is developed and applied to calculate the magnetic penetration depth in the Meissner state for a simple d-wave model of the cuprate high …
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Investigating the relationship between the superconducting and pseudogap states of the high-temperature superconductor Bi-2201 using scanning tunneling microscopy
… is considerable controversy regarding the nature of the relationship between the superconducting and pseudogap states of high-temperature superconductors. Although there exist a large number of theories regarding their relationship, the theories fall into one of two broad classes. The first class …
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Active materials in photonic crystals
… arising from embedding active materials inside of photonic crystal structures. These structures strongly modify the photonic local density of states (LDOS), leading to quantitative and qualitative changes in the behavior of active materials. First, I show that the emission spectrum of point-like …
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STM Study of Interfaces and Defects in 2D Materials
… and spectroscopy (STM/STS) investigation of interfaces and defects 2D transition metal dichalcogenides (TMDCs). The first part of the thesis focuses on the synthesis of 2D TiSe2 with chemical vapor transport (CVT). By properly choosing the growth condition, Sub-10 nm TiSe2 flakes were …
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The electronic structure of galena and hematite surfaces: applications to the interpretations of STM images, XPS spectra and heterogeneous surface reactions
… scanning tunneling spectroscopy (STS) spectra of galena (PbS) and hematite (a-Fe203) were calculated using ab-initio methods in order to interpret experimental images and spectra that were taken in previous studies. These calculations have helped to understand which states of the mineral …
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Inverse Design of Random Emitters in Nanophotonics
… In this work, we present a trace formulation of random emitters that can be efficiently combined with inverse design, even for topology optimization over thousands of design degrees of freedom. We begin with a trivial case where the emitter is at a single location with random orientations, …
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Using multiplexers to study the statistics of quantum phenomenon in one-dimensional wires
… the differential conductance quantised in units of $G_Q=2e^2/h$. However, the transport behaviour below the first plateau is still not fully understood, including the 0.7 anomaly and the 0.25 anomaly in the linear and non-linear transport regimes respectively. In this work, we utilise a …
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Resonance Fluorescence in a Photonic Crystal
… for the atom, that modifies the decay of the exited state, especially if the atom frequency is close to the band gap. The population inversion is investigated als well as the emission spectrum. The dynamics is analysed in the context of open quantum systems. Due to the multiple …
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First-principles and Many-Body Methods: Implementations and Applications to Study Spintronic Materials
… materials are instrumental for the development of spintronic technology. Before we are able to engineer spintronic devices, it is necessary to understand the properties of materials from which spintronic devices are made, otherwise time and other resources will be wasted. In this thesis, we …
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Synthesis and Characterization of Platinum-Based Fuel Cell Catalysts
… were obtained by spontaneous deposition of Ru onto platinum nanoparticles. Their reactivity toward methanol oxidation maximized at ruthenium packing density 0.4--0.5, displaying twice the activity of the commercial Pt-Ru alloy catalyst. COs adsorbed on these Pt/Ru nanoparticle consisted …
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