Selectivity in multiple quantum nuclear magnetic resonance
Abstract
The theory of multiple-quantum nuclear magnetic resonance (NMR) is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first order systems and anisotropic systems with high symmetry) to show that an intensity decrease is expected if standard multiple-quantum pulse sequences are used. Pulse sequences are developed which excite coherences and produce population inversion only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible. Noise reduction from two dimensional spectroscopy, multiple-quantum NMR in exchanging systems, and statistical aspects of multiple-quantum coherence are also presented.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- December 1980
- Bibcode:
- 1980PhDT........30W
- Keywords:
-
- Molecular Excitation;
- Nuclear Magnetic Resonance;
- Quantum Mechanics;
- Electron Transitions;
- Molecular Structure;
- Particle Spin;
- Pulses;
- Atomic and Molecular Physics