A Pulse NMR Trilogy: Anomalies, Anisotropies, and Adsorption

Author: Schreiber, Loren Bennett

Year: 1975

Degree: Dissertation (Ph.D.)

Advisor: Vaughan, Robert W.

Committee Member: Unknown, Unknown

Option: Chemical Engineering; Chemistry

DOI: 10.7907/avna-2v77

Abstract

In phase one of this thesis, a systematic method, an extension of the average Hamiltonian formalism, is presented for calculating the effects of pulse errors in the multiple pulse nuclear magnetic resonance (NMR) experiments. Application of this method to account for effects of pulse nonidealities such as phase errors, phase transient effects, pulse size errors, and rf inhomogeneity is found to agree with experimental observation.

In phase two, the proton chemical shift tensor of the hydroxyl proton in calcium hydroxide was measured using multiple pulse NMR techniques. The tensor is axially symmetric with susceptibility corrected components of σ⊥ = -9.3 ± 1 ppm and σ∥ = +4.7 ± 1 ppm relative to TMS.

In phase three, conventional and multiple pulse NMR techniques were used to examine the hydroxyl protons on a series of high surface area silica-aluminas whose composition varied from 0-100% SiO2. Protons remaining on these materials after being calcined at 500° C are found to exist as immobile and isolated hydroxyl groups at room temperature. With the high silica content samples, 100-75% Si02, no AlOH groups were detectable, while on the 50% and lower SiO2 content samples, most protons were A1OH groups; thus, there is indication of a major change in local structure between 75% and 50% silica content.

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