Date of Award

Spring 2026

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Dr. S. Michael Angel

Abstract

This dissertation describes the use of multiple Raman spectroscopic techniques for the detection and characterization of non-hazardous organic and inorganic compounds. The first two applications involve the use of Raman and surface enhanced Raman spectroscopy to thoroughly analyze autoinducers (AI) produced by gram negative bacteria. The second set of applications involves the use of anti-stokes Raman and resonance Raman spectroscopy to remotely detect inorganic compounds at distances of up to 12 meters away.

This work describes the use of Raman spectroscopy for the characterization and discrimination of signaling molecules used in bacterial communication. Our initial work shows the potential of Raman spectroscopy to discriminate between various crystalline N-acyl homoserine lactones (AHLs). The most pronounced spectral differences were due to the alkane chain length of the amide linked side chain of the molecule, and the carbonyl substitution on the third carbon of the N- (beta-Ketocaproyl)-DL- homoserine lactone. However, AHLs typically exist in aqueous environments in the nM to mM concentration range. Since non-enhanced Raman spectroscopy not capable of reaching detecting AHLs in their natural aqueous environment, we used surface enhanced Raman spectroscopy to increase our limit of detection. There is a significant enhancement in the Raman intensity observed from AHLs when the molecules are adsorbed to the gold colloids, which were used as the SERS substrate. This increase in sensitivity allows us to record a biologically relevant detection limit of 45 uM. We were also able to spectrally discriminate between the AHLs used in this study.

The focus of the work then shifts to illustrate the capability of remote measurements using Raman spectroscopy. A portable AOTF coupled anti-stokes remote Raman system that is used to suppress fluorescence is described. In this work, we obtain fluorescent-free Raman spectra and Raman images of sulfur and titanium dioxide in the presence of a highly fluorescent background. We also show the capability of the system to spatially and spectrally discriminate between two materials in the presence of a fluorophore. Chapter four describes another telescope based remote resonance Raman system used to detect and characterize a pigment in ambient light conditions. In this work we discuss the effect of laser power, excitation wavelength, and analyte concentration on the measured resonance Raman intensity.

Rights

© 2026, Jasmine Ervin Gardner

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