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Raman spectroscopy of biological molecules and inorganic compounds

Posted on:2010-06-04Degree:Ph.DType:Dissertation
University:University of South CarolinaCandidate:Gardner, Jasmine ErvinFull Text:PDF
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.Chapters two and three describe 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 acyl-homoserine lactones (AHLs). This study served as foundational work to discover in what ways we could discriminate between AHLs with similar molecular structures. The overall goal of this project is to monitor and discriminate AHLs in their natural environment at concentrations ranging from ppb to ppm. So for this, we used surface enhanced Raman spectroscopy to increase our limit of detection. The second part of this work shows that there is a significant enhancement in the Raman intensity of the AHL when it is adsorbed to gold colloids, which were used as the SERS substrate. This increase in sensitivity allows us to record a limit of detection of 45 muM, which is at the high end of biological relevancy for this molecule. We were also able to spectrally discriminate between the AHLs used in this study.Chapters four and five contain work that illustrates the capability of remote measurements using Raman spectroscopy. Chapter four describes a portable AOTF coupled anti-stokes remote Raman system used to suppress fluorescence. 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 anti-stokes system to spatially discriminate between two materials in a fluorescent matrix. Chapter five 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.
Keywords/Search Tags:Raman spectroscopy, Inorganic compounds, Resonance raman, Raman intensity, Raman system used
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