The Effects of Highly Reflecting Materials on Nearby Fluorescent Probes
Brazas, John Charles, Jr.
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Permalink
https://hdl.handle.net/2142/70242
Description
Title
The Effects of Highly Reflecting Materials on Nearby Fluorescent Probes
Author(s)
Brazas, John Charles, Jr.
Issue Date
1983
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Analytical
Abstract
This study has demonstrated the effects of highly reflecting materials on fluorescent molecules spaced within several thousand angstroms of that surface. The specific light environment resulting from reflection will affect the emission intensity and the lifetime of the excited state of these molecules. A layered system was designed and assembled allowing the positioning of a thin layer of fluorescent molecules to serve as a probe of the environment at a given distance from the reflecting surface. The typical profile of the experimental system was support/reflecting material/transparent spacer/probe layer. The probe layer was produced by spin-coating and the other layers by thermal evaporation.
A mathematical description was derived for the light intensity at the probe layer. This intensity is dependent on the wavelength of light, spacer thickness, angle of excitation and emission collection, and the refractive indices of the layers.
The refinement of the layer interfaces, optical constants, thicknesses, and reproducibility of assembly was investigated. The analysis of the system provided the information necessary to demonstrate the accuracy of the theoretical description of the assembly.
The system demonstrated a good correlation with theory. The dependence of the intensity of the probe layer emission on the angle of excitation or emission collection can be used to determine the optical thickness of the spacer layer. Using this information in conjunction with the effect of the environment on the spectral characteristics of the probe, the refractive index and any birefringence of the spacer layer can be determined.
Versatility is demonstrated by the use of different materials and its the application to less ideal conditions. Additional effects were demonstrated in the time domain as the fluorescence decay rate shows a dependence on the optical distance of the probe layer from the reflecting surface.
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