Doctoral Dissertations

Date of Award

12-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Michael J. Sepaniak

Committee Members

Tuan Vo-Dinh, James Q. Chambers, Earl L. Wehry, Robert N. Compton

Abstract

This two-part study investigates the feasibility of selective detection in remote analysis based on 1) surface-enhanced Raman scattering (SERS), and 2) separations-based fiberoptic sensing (SBFOS).

For the first case, the extremely sharp spectral features of Raman scattering can sometimes allow the analysis of multicomponent samples without complicated sample pretreatment steps. Furthermore, the giant signal-enhancing effect of SERS can enable trace level detection. A solid, surface-based metallic substrate approach is taken for the development of a practical SERS technology. Various substrates are described, including silver-coated alumina, silver-coated Ti02, and silver islands. These substrates are economical and easy to fabricate with a high degree of reproducibility. Furthermore, they are readily integrated with fiberoptic sensors for remote SERS detection. Three fiberoptic SERS sensor systems are described in this work. The surface-based substrates are also applied to the detection of organic vapors.

In the latter case, the high separation efficiency of capillary electrophoresis is coupled with laser-induced fluorescence (LIF) detection in the development of a fiberoptic sensor. Although LIF can offer exceptional detectability, its application to the analysis of complex samples can be difficult due to the broadband nature of fluorescence. It often requires sample pretreatment steps such as separations. In the SBFOS approach, separations can be performed remotely. Several complications are associated with the development of CE-based SBFOSs and are described in this work. Four SBFOS designs are described and applied to analysis environmentally and biomedically significant samples.

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