none

Thesis (Ph. D.)--University of Chicago, Dept. of Economics, June 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 270-292). Also available online.

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 8, 2010)

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 270-292). Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 324-353).

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1922. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed February 23, 2010)

This thesis presents spectroscopic studies of metallic nanoparticle localized surface plasmons and plasmon enhanced fluorescence. We investigated the dielectric sensitivity of silver nanoprisms to an external electric field and gold nanorods to the formation of a self-assembled surface monolayer. Dark field microscopy was used to image plasmonic scattering from single nanoparticles, and a liquid crystal tunable filter was used to construct corresponding spectra. The plasmon resonances of silver nanoprisms displayed both reversible red shifts and irreversible blue shifts along with drastic intensity changes upon exposure to an applied bias. The plasmon resonances of gold nanorods showed sensitivity to the presence of alkanethiol molecules adhered to the particle surface by a moderate red shift. An increase in the effective external dielectric caused a shift toward longer wavelengths. We imaged plasmon enhanced fluorescence in order to optimize experimental parameters for a developing project that can characterize nanoparticle structure on sub-wavelength dimensions. Preliminary controls were performed to account for the effect of O₂ plasma treatment, solvent and alkanethiol monolayer formation on surface plasmon resonances. We found that O₂ plasma treatment for different time intervals did not result in a plasmon shift compared to untreated nanoparticles exposed to N₂; however when exposed to solvent the surface plasmons of the treated particles shifted five times as far toward the red. Interestingly, the solvent effect only resulted in a plasmon shift when the particles were N₂ dried after solvent incubation. Gold nanorods incubated in ethanol showed no wavelength maximum shift in pure solvent over time, but shifted moderately to the red after incubation in a solution of alkanethiol molecules. Conditions for the plasmon enhanced fluorescence study were optimized using a dye conjugate of the same alkanethiol molecule used previously by formation from solution in a monolayer on the gold nanorod surface. The appropriate synthesis for dye functionalization, molecular concentrations, solvents and optical settings were determined. / text

Catalysts are essential for technological advances, because of their indispensable role in chemical and material manufacturing, energy conversion, and pollution control systems. Developing better catalysts is a highly desired goal that is impeded by the complexity of heterogeneous catalysts. This makes it extremely difficult to obtain information regarding active sites and reaction mechanisms, which is critical for improving catalyst design and performance. My research work has led to the understanding of how specific catalytic surface sites affect the performance of catalysts by constructing conceptually simpler planar model catalysts for kinetics and mechanism studies using model surface science tools and batch reaction testing. The work in this dissertation has demonstrated that planar model catalysts are versatile tools to probe reaction mechanisms on industrial catalysts. Supported gold nanoparticles have shown remarkable catalytic activity in a variety of reactions. However, many fundamental aspects of gold catalysts are still unclear, especially about the identity of active sites and oxidizing species. A Au(111) single crystal, the most stable and abundant facet on gold nanoparticles, is utilized to understand the reaction mechanisms of partial oxidation of 2-butanol and allyl alcohol. By controlling oxygen coverage on the surface, 100% selectivity to corresponding ketone and aldehyde, the desirable products, can be achieved. Two model catalysis systems, gold nanoclusters supported on a TiO₂(110) substrate and iron oxide dispersed on a Au(111) surface, were employed to understand the reaction pathways of CO oxidation and probe the role of the oxide/metal interface. The mechanistic and kinetic studies have shown that planar model catalysts are useful tools to probe reactions on industrial catalysts. The mechanistic understanding obtained from model catalyst studies can be used to create better catalysts. / text

Catalyst development is important to the contemporary world as suitable catalysts can allow chemical processes to proceed with reduced energy consumption and waste production. In order to design catalysts with improved performance, the fundamental studies that correlate catalytic properties with surface structures are essential as they can provide mechanistic insights into the reaction mechanism. Pd−Au bimetallic catalysts have shown exceptional performance for a number of chemical reactions, however, the interplay between the reactive species and surface properties are still unclear at the molecular level. In this dissertation, the catalytic chemistry of Pd−Au surfaces was investigated via model catalyst studies under ultrahigh vacuum conditions. A range of Pd−Au model surfaces were generated by annealing Pd/Au(111) surfaces and characterized/tested by surface science techniques. The findings in this dissertation may prove useful to enhance the fundamental understanding of structure-reactivity relation of Pd−Au catalysts in associated reactions.