Title page for ETD etd-03072003-124722


Type of Document Dissertation
Author Salido, Sandra I
Author's Email Address ssalido@myyellowstone.net
URN etd-03072003-124722
Title Flow 1H Dynamic Nuclear Polarization Studies in Normal Liquids and Supercritical Fluid Carbon Dioxide
Degree PhD
Department Chemistry
Advisory Committee
Advisor Name Title
Dorn, Harry C. Committee Chair
Anderson, Mark R. Committee Member
Tanko, James M. Committee Member
Taylor, Larry T. Committee Member
Wightman, James P. Committee Member
Keywords
  • Proton
  • Polarization
  • Supercritical fluid
  • Nuclear
  • Dynamic
Date of Defense 2002-12-13
Availability unrestricted
Abstract
Flow 1H dynamic nuclear polarization (DNP) experiments of small probe molecules (i.e. chloroform and benzene) were conducted in normal liquids (i.e. neat benzene, deuterated benzene, chloroform) and supercritical fluid CO2. Initial data collected on the 14N NMR line width of acetonitrile in normal liquids and SF CO2 resulted in a 2-6 factor increase in the molecular motion of the molecule in the SF--the result of which corresponds to the expected factor increase in DNP signal enhancements in the low viscosity fluid. Observed DNP signal enhancements were 2-5 times greater in the supercritical fluid versus the normal liquids in both the solid-liquid intermolecular transfer (SLIT) and liquid-liquid intermolecular transfer (LLIT) experiments. Significant changes in the electron spin-spin (T1S) and spin-lattice (T2S) relaxation times of the nitroxide radical TEMPO in neat benzene, deuterated benzene, and SF CO2 were noted; the T1ST2S product (calculated from DNP saturation plots) of the LLIT DNP data were compared.

Due to the high pressures and elevated temperatures necessary for optimum flow DNP with SF CO2 (e.g. P = 2310 psi, T = 313 K), high pressure flow cells were developed (and, also, adapted to a commercially available probe in the NMR regime) using PEEK (polyetheretherketone) material.

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