University of Illinois Urbana-Champaign

NMR Studies of Solid-Supercritical Fluid Mixtures and a New Technique for NMR Diffusion Measurements

Lamb, Douglas Matt

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Description

Title
NMR Studies of Solid-Supercritical Fluid Mixtures and a New Technique for NMR Diffusion Measurements
Author(s)
Lamb, Douglas Matt
Issue Date
1988
Doctoral Committee Chair(s)
Jonas, Jiri
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Physical
Abstract
  • Solid solubilities of naphthalene in supercritical carbon dioxide have been measured near the upper critical end point of the binary mixture by using a novel, in situ NMR technique. The pressure-temperature trace of the solid-liquid-gas phase line that terminates at the upper critical end point was also determined. The results are discussed in terms of the supercritical solubility theory of Gitterman and Procaccia. The analysis correlates the composition and phase data.
  • The use of supercritical fluid solvents to obtain NMR line narrowing for solutes containing quadrupolar nuclei was investigated. It is shown that for certain solute-supercritical fluid systems linewidth improvements of two to six fold over organic solvents are possible.
  • A new technique for diffusion measurement by NMR using a fixed field gradient is described. The method makes use of a Bessel function fit analysis to the spin-echo signal in order to determine both the applied gradient and the diffusion coefficient simultaneously. Results of tests of the method are presented, and the utility of the technique is demonstrated.
  • An NMR study of the molecular motions of naphthalene in the naphthalene-supercritical carbon dioxide mixture was performed. Both the diffusion coefficient of naphthalene and the deuterium spin lattice relaxation time of d$\sb8$-naphthalene have been measured. Data have been obtained over two distinct phase regions of the mixture. The results are analyzed using hydrodynamic theory through the Stokes-Einstein and Debye equations. Empirical modifications of these equations are necessary to represent the data.
Graduation Semester
1988
Type of Resource
text
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http://hdl.handle.net/2142/70401

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