Motional effects on optimum coherence transfer in 2H MAS NMR spectroscopy Original Research Article

The detailed mechanism of coherence transfer in 2H MAS NMR spectroscopy is investigated in the presence of molecular motion. An elaborate theoretical formalism is developed that exploits the properties of Lie algebras to characterize the states of nuclear spin ensembles and to identify the allowed coherence transfer pathways. The functional form of the coherence transfer functions is investigated within the Floquet–Poincaré formalism. Based on these principles a general methodology is described for evaluating the optimum pulse parameters consistent with maximum sensitivity. The intensity and phase distortions induced by the optimum pulse parameters are discussed and the importance of incorporating these effects in theoretical simulations is examined. The results are verified by experimental spectra of polycrystalline thiourea-2H4 that are analyzed in terms of a discrete motional model.