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 11 of 11 for “"Boson peak"”.
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Raman Spectroscopy Of Glasseswith High And Broad Raman Gain In The Boson Peak Region
… the relationship between glass structure and the Boson peak (enhancement of the low-frequency vibrational density of states) and report new inelastic neutron scattering spectra for niobium-phosphate glasses. Polarization resolved Raman spectra of glasses based on tellurite and phosphate formers …
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Vibrational dynamics in strong glasses: the cases of densified v-SiO2 and v-SiSe2
… glasses focusing on the origin and nature of the boson peak (BP). This feature is an universal characteristic of glasses and a fingerprint of the presence of disorder. Two samples have been chosen for this study. The first is permanently densified vitreous SiO$_2$. Permanent densification has been …
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Quantum Theory of Glasses
… of around two hundred molecular units. The Boson Peak and the plateau in thermal conductuvity, observed at higher temperatures, arise from the same motions but the motions are no longer fully coherent.
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Non-affine lattice dynamics of disordered solids
… scalings behaviours of the position of the boson peak. Furthermore, we describe the elastic heterogeneities occurring in a bond-depleted two- dimensional lattice with long-range interactions. The dependence of the concomitant correlations of the local elastic moduli are studied in detail in …
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Neutron scattering investigations on the unusual phase behavior of water
… as dynamic crossover, dynamic heterogeneity and boson peak, are observed above the conventional glass-transition temperature. Possible explanations are discussed in the frameworks of the liquidliquid critical point scenario of water and the extended mode-coupling theory. Computer simulations are …
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Terahertz spectroscopy to explore the role of vibrational dynamics in systems with varying structural order and disorder
… in increased anharmonic effects, obscured the boson peak, and influenced the vibrational density of states. The effect of the relative water content in aqueous mixtures of glycerol at room temperature was also explored. By utilising four different model biopharmaceuticals, the effect of size on …
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Neutron scattering investigations on the liquid-liquid transition in deeply cooled confined water
… the dynamic properties, including the so-called "boson peak", the librational motion, and the relaxation process of the confined water, are also studied with dynamic neutron scattering. The time scales of these motions cover a broad range from 10-2 picosecond to hundreds of nanoseconds. The …
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A viscoelastic hydrodynamic approach to the density fluctuations in classical liquids
… suggested, that is, the puzzling low-frequency boson peak and the beta-relaxation may be different manifestations of the transverse modes in liquids with different fragility. In a parallel manner, the idea of viscoelastic hydrodynamics is also applied to describe the density fluctuations …
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From atoms to cities : A bottom-up analysis of infrastructure materials and systems
… vibrational modes at low THz regime known as Boson peak. These models are further utilized to calculate the heat capacity and transport properties using Green-Kubo formalism in equilibrium molecular dynamics. While considering other phases in cement paste, the use of mean-field homogenization …
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The Dynamics of Molecular Glasses Studied by Light Scattering
… whole dielectric spectrum including the alpha-peak, its high frequency wing, and fast dynamics, is applied. The crossover temperature extracted from the phenomenological analysis and defined by the emergence of the high frequency wing upon cooling agrees well with the critical temperature …
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Vibrational and mechanical properties of disordered solids
The recent development of a framework called non-affine lattice dynamics made it possible to calculate the elastic moduli of disordered systems directly from their microscopic structure and potential energy landscape at zero temperature. In this thesis different types of disordered systems were …