UBC Theses and Dissertations
Electric quadrupole interaction in the nuclear magnetic resonance Smellie, Donald William
The general case of the dependence on crystal orientation of the frequency splitting of the nuclear magnetic resonance absorption line in a single crystal sample into 21 components due to the coupling between the nuclear electric quadrupole moment and the electric field gradient in the crystal at the site of the nuclei in question is examined both theoretically and experimentally. The theoretical part of this thesis consists of a detailed exposition of the first order perturbation theory applicable to crystals with axially symmetric fields which was outlined in condensed form by Prof. R. V. Pound, and of the extension of this first order theory to non-axially symmetric cases suggested by Prof. G. M. Volkoff. The experimental part of this thesis consists of the description of an exploratory experiment proposed by the author, and performed by him, with some assistance from Mr. H. E. Petch, for the purpose of obtaining a preliminary check on the theory, and of demonstrating the feasibility of a later more carefully performed experiment. Such an experiment with an improved crystal mount has since then been performed by Mr. Petch. A single crystal of spodumene was used, and the angular dependence of the frequency splitting for Li⁷was measured as the crystal was rotated about the C-axis of its monoclinic structure. The apparatus used was an oscillating detector type of nuclear magnetic resonance spectrometer previously designed and built by Dr. T. L. Collins. The axis of rotation of the crystal was kept perpendicular to the uniform magnetic field of the spectrometer. The direction of the b-axis of the crystal inferred from this rotation was found to coincide within experimental error with, its orientation as obtained later by standard optical methods. An experiment was designed to indicate the relative magnitudes of the spin-lattice relaxation by magnetic dipole and electric quadrupole coupling is proposed.
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