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 49 for “"excitation spectrum"”.
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Evolution of the excitation spectrum of cuprate superconductors with doping and temperature
… the scanning tunneling microscope to measure the excitation spectra in the cuprates on the atomic scale as a function of doping and temperature. In this thesis, we will describe these techniques as well as a series of new experiments that reveal a surprisingly simple picture of how …
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Effect of potential shape and excitation spectrum on power harvested from ambient vibration
In recent years, there have been experimental developments in energy harvesting from ambient vibrations in small-scale sensing. The ultimate goal is to replace batteries in these sensors. Linear systems have a narrow bandwidth, but ambient vibrations occur over a potentially broad range of …
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Many-body effects in the thermodynamic properites of Fermi liquids and the electron-phonon system and in the excitation spectrum of liquid 4HE
… potential theory to the description of the excitations of liquid 4He at low temperature and I use recent experimental results to determine the parameters in the theory. I calculate the dispersion curve in the absence of dynamic mode-mode coupling and discuss the results.
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Many-Body Effects in the Thermodynamic Properties of Fermi Liquids and the Electron-Phonon System and in the Excitation Spectrum of Liquid Helium-4
In this thesis I study two separate topics in many-body physics. In the first part I consider many-body effects in the thermodynamic properties of Fermi liquids and of the electron-phonon system. Using normal liquid ('3)He as an example, I show that the T('3)lnT corrections due to spin fluctuations …
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Group IIB dimers: Spectroscopy of molecular cadmium and gain demonstration in molecular mercury
… \sp1P\sb1),$ was studied by laser excitation spectroscopy from the lowest metastable state, $\rm a\sp3\Pi\sb{g}.$ The excitation spectrum of the $\rm B\sp1\Sigma\sbsp{u}{+}\gets a\sp3\Pi\sb{g}$ transition in the 555-725 nm spectral range is presented. Birge-Sponner analysis of the …
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Topics in low temperature Fermi liquid theory
… liquids are discussed including the elementary excitation spectrum of 3 He under pressure, spin polarized 3 He, and an early attempt to formulate a Fermi liquid theory to describe the low temperature thermodynamic and transport properties of the heavy electron system UPt3. The elementary …
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Light scattering on the high-temperature superconductors
… inelastic background scattering or the phonon excitation spectrum.
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Temperature dependence of impurity resonances in cuprate superconductors
… the superconducting gap in the electronic excitation spectrum prevents scattering of low energy electrons. In high temperature superconductors (HTS) an additional gap, the pseudogap, develops well above the superconducting transition temperature Tc. The identity of this pseudogap and its …
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A System For Conducting Laser-Induced Fluorescence Measurements On Gas Mixtures Exposed To Alpha Radiation
… nm. The data collected was used to produce an excitation spectrum to compare with a simulated spectrum. These mixes were diluted with an ultra-high purity grade of N<sub>2 </sub>so that an experimental detection limit could be approximated. The excitation spectrum produced is in excellent …
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Eta photoproduction study with the upgraded Glasgow tagger at MAMI
… an excellent means by which to study the proton excitation spectrum. The existence and properties of some nucleon resonances are well established, but many more are still debated, meriting much theoretical and experimental attention. The proximity and widths of such excited states result in …
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Correlations in the one-dimensional Hubbard model
… Large Coulomb repulsion induces a gap in the excitation spectrum and a metal-insulator transition is predicted as the Coulomb repulsion parameter is changed.
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Angle-Resolved Photoelectron Spectroscopy Studies of the Many-Body Effects in the Electronic Structure of High-Tc Cuprates
… is that it gives access to the single-particle excitation spectrum of the material as a function of both momentum and energy with very high resolution. Other experimental techniques, such as inelastic neutron scattering (INS), Raman spectroscopy, or the newly estab-lished Fourier-transform …
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VUV emission from the heavy alkali metals and rare gas impurities in alkali metals
Core excitations in metals create a local change in potential that couples strongly to the sea of conduction electrons. The response of the electron liquid to this local shock is reflected in its excitation spectrum; this can be probed by various core-level spectroscopies. The research described in …
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Cyclotron resonance in cadmium telluride
… field in the (110) plane of the sample. An excitation spectrum revealed a maximum in the photosensitivity in the region of the first direct exciton peak. Changes in the shape of the resonance spectrum as a function of the intensity and wavelength of the incident illumination ""Tare recorded."
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Thermodynamic and tunneling measurements of van der Waals heterostructures
… measurements that access its quasiparticle excitation spectrum. Both techniques were applied to van der Waals materials, a class of crystals composed of layered atomic sheets with weak interplane bonding which permits the isolation of single and few-layer sheets that can be manually …
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Coulomb drag in quantum Hall systems near v = 1/2
… more accurate in this long wavelength limit. The excitation spectrum of the system in the absence of scattering consists of a discrete spectrum of 6 function poles. We introduce tools to deal with such expressions, but we find that we cannot yield any exact results from this approach due to …
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Topics in the Theory of High-Temperature Superconductors
… superconductors exhibit a pseudogap in the excitation spectrum above the superconducting transition temperature. It is likely that an understanding of the relationship between antiferromagnetism and superconductivity as well as an understanding of the nature of the pseudogap will be …
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Inter-Rydberg excitation spectroscopy of krypton dimers
An excitation spectrum of the krypton dimer 6p$\sp3\Pi\sb{\rm g}(0\sbsp{g}{-})$ $\gets$ 5s$\sp3\Sigma\sbsp{\rm u}{+}(1\sb{\rm u}$, 0$\sbsp{\rm u}{-})$ transition has been observed over 525 nm $\leq$ $\lambda$ $\leq$ 545 nm. An argon fluoride excimer laser was used to excite the atomic krypton 6p …
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Collective excitations in low dimensional systems and stochastic control of population growth in a fluctuating environment
… problems in the following areas: collective excitations in condensed matter physics, noise in gene network and stochastic control in biophysics. In the first area, I construct an effective field theory to describe Bose-Einstein Condensate (BEC) realized in an external potential. This theory …
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Spin fluctuations and high temperature superconductivity in the copper oxides
… and the superconducting properties. With a spin excitation spectrum and a quasiparticle-paramagnon coupling determined by fits to normal state experiments, the author obtains high transition temperatures and energy gap behaviors comparable to those measured for YBa2Cu301, YBa2Cu306.63 , and …
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