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Physical Sciences and Mathematics Commons

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Full-Text Articles in Physical Sciences and Mathematics

Computational Studies For Optimization And Design Of Extracting Agents For Separation Of Lanthanides And Actinides, Deborah Andrea Penchoff Dec 2014

Computational Studies For Optimization And Design Of Extracting Agents For Separation Of Lanthanides And Actinides, Deborah Andrea Penchoff

Doctoral Dissertations

Rare earths and actinides are of great interest given their varied applications in energy conversion and storage, such as in catalysis and batteries, and for advanced technological applications related to optical and magnetic properties (including electronics and automotive), amongst others. Many of the rare earth elements are considered endangered species due to their unique properties which have no clear alternatives that will maintain performance for important applications. The optimal approach is to find readily available alternatives for critical materials to ensure a certain standard of living and quality of life for future generations, but it is very likely that reusing …


Methods For Quantitative Local Structure Analysis Of Crystalline Materials Employing High Performance Computing, Tara Marie Michels-Clark May 2014

Methods For Quantitative Local Structure Analysis Of Crystalline Materials Employing High Performance Computing, Tara Marie Michels-Clark

Doctoral Dissertations

A fundamental computational methodology was investigated to extract quantitative local structure information from single crystal diffuse scattering data. The principles of a highly efficient, parallelizable local structure analysis using massively parallel computing resources at Oak Ridge National Laboratory (ORNL) are demonstrated on an organic hydrocarbon compound containing stacking faults, Tris(bicyclo[2.1.1]hexeno)benzene. A probabilistic model of the stacking variations with a five layer interaction depth was developed. The final model structure motif statistics are verified using the steady state distribution of Markov matrix representing the four to five layer transitions. The computations revealed that highly parallelizable “structure-clones” could replace less computationally efficient …


Understanding The Plasmonic Properties Of Metallic Nanostructures With Correlated Photon- And Electron-Driven Excitations, Vighter Ozezinimize Iberi May 2014

Understanding The Plasmonic Properties Of Metallic Nanostructures With Correlated Photon- And Electron-Driven Excitations, Vighter Ozezinimize Iberi

Doctoral Dissertations

The collective oscillation of the conduction band electrons in metal nanostructures, known as plasmons, can be used to manipulate light on length scales that are smaller than the diffraction limit of visible light. In this dissertation, a correlated approach is used to probe localized surface plasmon resonances (LSPRs) in metallic nanostructures, and their application to surface-enhanced spectroscopy. This correlated approach involves the measurement of LSPRs with dark-field optical microscopy (resonance-Rayleigh scattering), and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). Structural parameters of the exact same nanostructures obtained from the STEM are subsequently used in performing fully …