| In this thesis, we study model problems that capture the essence of dipolar re-coupling in magic angle spinning NMR (nuclear magnetic resonance) spectroscopy. We also address the problem of ensemble control where elements of an ensemble show variation in parameters that govern the system dynamics and make control and measurement difficult. We provide explicit methods to overcome and compensate dispersions across the ensemble using composite pulse sequences, phase modulation, and adiabatic passage. The methodologies developed are used to design novel pulse sequences that make heteronuclear and homonuclear recoupling experiments broadband and insensitive to rf inhomogeneity and anisotropic interactions. We finally incorporate these experiments into multidimensional solid-state NMR experiments that use powder dephased antiphase coherence (gamma preparation) to encode chemical shift information. This allows for the complete transfer of transverse magnetization giving improvements in sensitivity and resolution. Experimental confirmation of these results are obtained from a variety of molecular systems. |
