Thesis (Ph. D.)--University of New South Wales, 2000. / Includes bibliographic references. Also available online.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Brédas, Jean-Luc; Committee Member: Kippelen, Bernard; Committee Member: Marder, Seth; Committee Member: Sherrill, David; Committee Member: Whetten, Robert. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Universiẗat, Diss., 1999--Hamburg.

Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2005. / "August, 2005." Title from electronic dissertation title page (viewed 09/24/2005). Advisor, David A. Modarelli; Committee members, Matthew Espe, Michael Taschner, Chrys Wesdemiotis, Stephanie Lopina; Department Chair, David Perry; Dean of the College, Charles B. Monroe; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 62-66).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 126-130).

Plasmon coupling is known to cause distance dependent red-shifts of the characteristic plasmon resonance and localize strong electric fields to the gap between individual nanoparticles. These effects form the basis of nanoscale plasmonic sensors designed by creating specic structures of coupled nanoparticles. The simplest of these structures, a nanoparticle dimer, can easily be assembled through molecular self-assembly, resulting in a structure called a plasmon ruler. These plasmon rulers are crucial tools for the measurement of nanoscale distances, but the impact of the molecular linker on the plasmonic response of the coupled system remains insufficiently understood. In this dissertation, plasmons rulers composed of 40 nm gold nanoparticles are utilized to systematically investigate the potential effects of one molecular linker, DNA, on the strength of the plasmon coupling at a variety of interparticle separations. The strength of the plasmon coupling is determined based on the shifting of the plasmon resonance, which, at separations below 2.7 nm, is significantly blue-shifted when compared to expected values from electromagnetic simulations and experiments without DNA linkers. This deviation indicates a reduced charge accumulation on the nanoparticles in the gap region and is ascribed to DNA-mediated charge transfer. Enhancements to the charge transfer capabilities of the DNA were also investigated, through the deposition of interstitial palladium nanocrystals on the DNA linkers. The deposition of these nanocrystals results in a variety of structural changes to the plasmon rulers, associated with blue- and red-shifts of the plasmon resonance relative to electromagnetic simulations without gap material and experimental spectra of structures without molecular or metallic linkers. The relative blue-shift of the resonance results from a variety of scenarios, including short interparticle separations bridged by DNA or palladium nanocrystals, the build-up of palladium nanocrystals within the gap, or the incorporation of discrete palladium nanoparticles in the DNA linkers. The underlying mechanisms of the observed spectral shifts are analyzed. The red-shifted resonances resulted from a significant build-up of palladium nanocrystals in the gap, effectively linking the gold nanoparticles and forming a hybrid nanorod-like structure.

>Magister Scientiae - MSc / The efficiency of organic photovoltaics is influenced by the structure of the polymer, the morphology of the film, the interfaces between the layers, the choice of electron acceptor material and the ratio between the electron acceptor material and the polymer. In this project, we have used regioregular poly (3-hexylthiophene) (rr-P3HT) as the electron donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), a derivative of the C60 fullerene, as the acceptor material. Different weight-ratios of rr-P3HT to PCBM were prepared by stirring for several hours in a chloroform solution and subsequently spin coated onto crystalline silicon and transparent conductive oxide/glass substrates. The effect of the PCBM concentration on the photo-induced optical emission and absorption properties of rr-P3HT was investigated by photoluminescence and ultraviolet-visible spectroscopy, respectively. Changes in the structural properties, as a function of the weight-ratio, were probed by high-resolution transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. Results show that the structural integrity and crystallinity of rr-P3HT is compromised with the addition of excessive amounts of PCBM, which has a negative impact on the optical absorption of rr-P3HT and the photo-induced charge transfer mechanism between the rr-P3HT and PCBM. This work illustrates that blending rr-P3HT with an equal weight of PCBM results in an optimum configuration for improved performance in organic photovoltaic devices.

214 pages / The Fock-Tani (unitary) transformation of the second- quantized Hamiltonian gives a representation which treats reactants and products symmetrically, and composites exactly. Each term in the Fock-Tani potential corresponds to a specific physical process and contains terms orthogonalizing continuum states to the bound states. The difficulty in carrying out this transformation can be lessened by working in a center of mass system, giving (n-1) reduced mass particles. After a general analysis of such systems, the Fock- Tani transformations in the 3→2-body case are carried out for the reactions a⁺+(b⁺c⁻)→(a⁺c⁻)+b⁺ and a⁻+(b⁺c⁻)→(a⁻b⁺)+c⁻. It is found that for (2) the transformation in the symmetrical reduced mass system can easily be carried out, but the Jacobi reduced mass system requires the more complicated d-matrix approach. This transformation has not yet been attempted in the full 3-body system but is likely to be as difficult as that for (1). First order differential and total cross sections are computed for resonant charge transfer in (1) for a proton- hydrogen initial state. The Fock-Tani T-matrix for the initial-state Jacobi system is found to be identical to that for the full 3-body system. That for the symmetrical reduced mass system gives an error of order l/mprot in the incident wave vector. A comparison of the Jacobi version and a previous special case Fock-Tani transformation, where the proton mass is taken as infinite, is also made. Cross sections for (ls→ls) positronium formation in positron-hydrogen collisions, calculated using the same program as for the proton-hydrogen case, are found to disagree with the previous Fock-Tani result, probably due to lack of convergence of the previous result. Cross sections for reactions (1) involving muons in hydrogenic isotopes (of interest in quantum electrodynamics and catalyzed fusion) are also calculated. Finally, extension of the results to higher order is considered. Polarized Schrodinger wave functions for a system containing a hydrogenic atom and a fully kinetic external charge are found to first order. These would be used in the Fock-Tani matrix elements to account for some initial- and final-state effects. Calculations of distorted second-quantized states and second and third order T-matrix elements are also outlined.

abstract: Sunlight, the most abundant source of energy available, is diffuse and intermittent; therefore it needs to be stored in chemicals bonds in order to be used any time. Photosynthesis converts sunlight into useful chemical energy that organisms can use for their functions. Artificial photosynthesis aims to use the essential chemistry of natural photosynthesis to harvest solar energy and convert it into fuels such as hydrogen gas. By splitting water, tandem photoelectrochemical solar cells (PESC) can produce hydrogen gas, which can be stored and used as fuel. Understanding the mechanisms of photosynthesis, such as photoinduced electron transfer, proton-coupled electron transfer (PCET) and energy transfer (singlet-singlet and triplet-triplet) can provide a detailed knowledge of those processes which can later be applied to the design of artificial photosynthetic systems. This dissertation has three main research projects. The first part focuses on design, synthesis and characterization of suitable photosensitizers for tandem cells. Different factors that can influence the performance of the photosensitizers in PESC and the attachment and use of a biomimetic electron relay to a water oxidation catalyst are explored. The second part studies PCET, using Nuclear Magnetic Resonance and computational chemistry to elucidate the structure and stability of tautomers that comprise biomimetic electron relays, focusing on the formation of intramolecular hydrogen bonds. The third part of this dissertation uses computational calculations to understand triplet-triplet energy transfer and the mechanism of quenching of the excited singlet state of phthalocyanines in antenna models by covalently attached carotenoids. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016