NMR Spectroscopy of Exotic Quadrupolar Nuclei in Solids

• Author / Creator

  Faucher, Alexandra

• This thesis is concerned with NMR studies of solids containing NMR-active quadrupolar nuclei typically overlooked due to their unfavorable NMR properties, particularly moderate to large nuclear electric quadrupole moments. It is shown that 75As, 87Sr, and 121/123Sb NMR spectra of a wide range of solid materials can be obtained. Traditional 1D pulse sequences (e.g., Bloch pulse, spin echo, QCPMG) are used alongside new methods (e.g., WURST echo, WURST-QCPMG) to acquire the NMR spectra; the advantages of these new methods are illustrated. Most of these NMR spectra were acquired at an external magnetic field strength of B0 = 21.14 T. Central transition (mI = 1/2 to −1/2) linewidths of half-integer quadrupolar nuclei of up to a breadth of ca. 32 MHz are obtained at B0 = 21.14 T, demonstrating that nuclear sites with large nuclear quadrupolar coupling constants can be characterized. Many of the NMR spectra contained in this research depict situations in which the nuclear quadrupolar interaction is on the order of or exceeds the magnitude of the Zeeman interaction, thus rendering the high-field approximation invalid and requiring exact treatment in which the full Zeeman-quadrupolar Hamiltonian is diagonalized in order to properly simulate the NMR spectra and extract NMR parameters. It is also shown that both direct (Reff) and indirect (J) spin-spin coupling between quadrupolar nuclei can be quantified in some circumstances, and that the signs of the isotropic indirect spin-spin coupling and the nuclear quadrupolar coupling constants can be obtained experimentally in cases of high-field approximation breakdown. This research represents a relatively large and valuable contribution to the available 75As, 87Sr, and 121/123Sb NMR data in the literature. For example, experimentally determined chemical shift anisotropy is reported for the 87Sr nucleus in a powdered solid for the first time, and the NMR parameters for 11B-75As spin-spin coupling constants reported here add to a sparse collection of information on quadrupolar spin-pairs. Overall, this research is a step towards the goal of utilizing the entire NMR periodic table for the characterization of molecular and crystallographic structure as well as structural dynamics.

• Subjects / Keywords

  • Quadrupolar nuclei
  • Antimony
  • High-field NMR spectroscopy
  • Strontium
  • Arsenic

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R31Z41Z47

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.