Date of Award
Doctor of Philosophy
For analytical applications, an often overlooked property of light is its plane of polarization. However, since life processes usually favor one enantiomeric isomer, polarization sensitive techniques are necessary to answer a variety of chemical questions. The crux of this thesis, therefore, will be to present recent advances in the measure- ment and utilization of the polarization properties of light;Since optical activity is usually an indication of biological activity, past or present, optical rotation detection (ORD) can impart a unique selectivity to the chromatographic analysis of complicated geochem- ical samples. The advantages of selective detection will be demon- strated for several coal liquids, and LC-ORD will be shown to be useful for the fingerprinting of coals as well as for following the degree of processing of a fossil fuel;A recent trend in liquid chromatography has been the develop- ment of microcolumn technology. Microcolumns can be operated at reduced cost, and frequently, with improved efficiency over con- ventional sized columns. Using selected Glan-Thompson polarizing prisms, a liquid based Faraday modulation cell and a laser source, a micropolarimeter has been constructed with a one microliter flow cell that is compatible with microcolumn chromatography. When an optically active solvent is used with the micropolarimeter, optically inactive analytes can be detected as they elute from a microcolumn. This technique, termed indirect polarimetry, has converted the very selective micropolarimeter into a sensitive universal detection scheme superior to the conventional refractive index detector. Additionally, it will be shown that indirect polarimetry can be used to detect analyte absorptions with excellent sensitivity. The theoretical and experimental considerations necessary to obtain simultaneous selective, universal and absorption information will be discussed;Finally, Raman spectra can be obtained by monitoring the polar- ization properties of a probe field while it interacts with a Raman shifted pump field. An analytical investigation of this technique, the Raman induced Kerr effect will be presented, along with a unique;optical null capable of suppressing spectral and nonresonant background interferences; *DOE Report IS-T-1189. This work was performed under Contract W-7405-eng-82 with the U.S. Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Donald Robert Bobbitt
Bobbitt, Donald Robert, "Analytical applications of ultrasensitive polarization measurements " (1985). Retrospective Theses and Dissertations. 8679.