Radio Frequency Gradient High Resolution Nuclear Magnetic Resonance Spectroscopy

Gradient enhanced high resolution NMR has become a standard method in recent years, where B0 gradients are employed to increase the selectivity of conventional magnetic resonance methods. Radio frequency gradient methods permit greater flexibility in experiment design, and this thesis is concerned with developing the necessary theoretical background for understanding and developing RF gradient experiments. The reason of the complexity of the analysis of the RF gradient experiments is that RF gradient pulse itself can have two effects simultaneously, one of which is coherence transfer and the other is generation of gradient-induced phase evolution. The normal product operator formalism doesn't separate these in a clear, intuitive analysis. In this thesis, a requantization methodology is developed to cleanly separate the two processes. The new methodology is applied to generate properties of RF gradient multiple quantum filters, and to design such filters for the maximum sensitivity. RF gradient multiple quantum spectra experiments were also developed. In a second part of the thesis, spatial square wave modulation via B0 gradient NMR experiments was explored as a means of achieving the maximum sensitivity through spatial modulation of the spins such that spins at all spatial locations contribute uniformly to the NMR signal during the detection period. Thesis Supervisor: Dr. David Cory Title: Professor of Nuclear Engieering Department Copies of the full thesis are available from the MIT Libraries' Document Services