Solid State Nuclear Magnetic Resonance of Quadrupolar Nuclei (Nmr)

Solid State Nuclear Magnetic Resonance has been used to study a variety of systems of geologic and chemical interest including feldspars, phyllosilicates, zeolites and aluminas. High magnetic field strengths (8.5 T) and Magic Angle Sample Spinning (MASS) yield high resolution spectra for quadrupolar nuclei with odd integral nuclear spins. Among the nuclei studied are ('27)Al, ('23)Na, and ('51)V. General considerations conserning the second order quadrupole interaction are discussed including the effect of nuclear spin, asymmetry parameter, magnetic field strength, magic angle and variable angle sampling spinning. Evidence for susceptibility broadening due to magnetic impurities is also presented. Octahedral and tetrahedral aluminum can be readily distinguished by their chemical shift differences. Octahedral aluminum resonates from 2 to 12 ppm and tetrahedral aluminum resonates from 55 to 80 ppm. Feldspars have been studied by both aluminum and sodium NMR. Ordering in feldspars is characterized by showing defined quadrupolar features whereas disordered phases lack any structure in their lineshapes. There is no evidence for octahedral aluminum in the feldspar glasses studied. The glass spectra are broad and featureless due to a distribution of NMR parameters. Sheet silicates with both tetrahedral and octahedral aluminum were studied. The octahedral aluminum chemical shift is independent of the composition while the tetrahedral shift increases from 4.4 to 2.5 ppm with an increase in the amount of fourfold aluminum. The prominent feature in their spectra are the numerous spinning sidebands due to paramagnetic impurities. The spectra were simulated to determine the relative amounts of four and sixfold aluminum. There is good agreement between the NMR simulations and the chemical analyses. Quantitation of the NMR signals from quadrupolar nuclei is discussed and the results are presented for aluminum. Lineshape and intensity distortions are produced at long pulse widths. The relative intensity of the NMR signal appears to be proportional to the size of the quadrupole coupling constant.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Kinsey, Robert Alan

• Chemistry, Physical

Identifier

(UMI)AAI8422103

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70253