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Title: Photophysical processes in organic semiconductors and amyloid fibrils
Author: Essex, Rosemary Jane
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2004
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This thesis is concerned with the photophysics of organic materials and intermolecular order of guest dyes in self-assembled protein structures. Photophysical processes in polyfluorenes and iridium-containing polyfluorenes copolymer complexes were investigated. Interchain singlet energy transfer processes were investigated by studying the copolymers in various concentrations in a polystyrene matrix. The amount of polyfluorenes in the co-polymers was also varied so that intrachain energy transfer processes could be studied. The singlet exciton decays were fitted to a stretched exponential function to obtain a value for the dimensionality of the system. It was found that although intersystem crossing is an important decay channel, a significant proportion of excitons must still undergo singlet diffusion before decaying back to the ground state. The binding of dye molecules to amyloid fibrils was investigated through a study of their morphology and chemical interaction. Native protein with dye was compared to fibrils with dye by various spectroscopic techniques, which illuminated a significant morphological difference. Possible binding sites between the dye an fibril were suggested. The excited-state dynamics of the dye bound fibrils was also investigated and were found to be considerably different from native protein with dye. The order of the system was investigated through polarisation anisotropy measurements. A new excited state species was found to exist in the fibrillised protein with dye, which also gave a negative anisotropy indicating a particular order in the system. The fibrils themselves are highly ordered and stable structures and the eventual aim is to utilise them as templates for optoelectronic devices.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available