Quadrupole nutation NMR studies

Quadrupole Nutation NMR Studies of Second Generation Faujasitic Catalysts... 

Study of relaxation times for spin I = ill nuclei in the quadrupole nutation NMR experiment has confirmed that they are inversely proportional to the linewidths of the quadrupole nutation NMR spectra/ In the end, a useful generalization is that, if the relaxation is fast, then the spectral lines will be broad Therefore, the relaxation times, Ti and Tz, for spin-lattice and spin-spin relaxations respectively, can be of very crucial importance as parameters in the NMR study of quadrupolar nuclei. 

Lin and Chao (1991) studied the variation of the cation distribution with the lanthanum exchange level in hydrated La,Na-Y zeolites by two-dimensional 23Na nutation NMR spectra in which the chemical shift and the quadrupole interaction could be separated. They proposed that the mobility of both water molecules and sodium ions can be reduced by lowering the temperature of the sample, and the migration of lanthanum ions from supercages to small cages causes the redistribution of sodium after dehydration... 

While the main recent advance in NMR has been the development of multidimensional spectroscopy, novel catalytic applications include in situ studies and two-dimensional (2D) solid-state techniques such as correlation spectroscopy, spin diffusion, and quadrupole nutation. Completely new techniques have appeared, such as multiple-quantum spin counting, and old ones have developed in quite unexpected directions. For example, cross-polarization, a 20-year-old experiment, has recently been applied to quadmpolar nuclei to yield important new information on heterogeneous catalysts. Magic-angle spinning (MAS) of quadru-polar nuclei has been extended to methods in which the sample is spun about two different angles either simultaneously or sequentially (DOR and DAS). These experiments have been made possible by the significant advances in NMR instrumentation in the last decade. 

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