New approaches to the characterization of resonances in the solid-state NMR spectroscopy of half-integer quadrupolar nuclei are explored, on the basis of the acquisition of heteronuclear separate-local-field spectra on rotating solids. In their two-dimensional version, these experiments correlate for each chemical site a second-order quadrupolar MAS powder pattern with the dipolar MAS sideband ...

Spectral intensities of quadrupolar nuclei and the radiofrequency (rf) pulse lengths for selective and non-selective excitation of any single-quantum NMR transition in the solid state are calculated. When nuclei of the same element occupy sites which experience different electric field gradients, the spectra are quantitatively reliable only when the length of the rf pulse is much smaller than n...

Stretched hydrogels make uniformly anisotropic environments for quadrupolar nuclei such as 2H, 23Na, and 133Cs. Such surroundings cause the partial alignment of nuclear spin bearing ions molecules that is sufficiently pronounced to alter magnetic resonance spectra guest species. In most cases, splittings are directly related quantum number I. The relative intensities components multiplets can b...

We report the observation of a new decoupling-induced recoupling phenomenon in multiple-quantum magic-angle-spinŽ . ning MQMAS NMR spectra of half-integer quadrupolar nuclei. The origin of the effect is identical to the second-order Ž . recoupling between dipolar and anisotropic chemical shielding interactions under continuous-wave CW spin decoupling, w Ž . x which is first observed by Ernst et...

We show that the two-dimensional one pulse (TOP) representation of magic-angle spinning nuclear magnetic resonance data of half-integer quadrupolar nuclei has significant advantages over the conventional one-dimensional spectrum. The TOP spectrum, which correlates NMR frequency to spinning sideband order, provides a rapid determination of the number of sites as well as the size of the their qua...

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Chemical shift anisotropy (CSA) has been an invaluable probe of structure and dynamics for a variety of systems in NMR spectroscopy. Unfortunately, the presence of strong quadrupolar couplings has severely limited the ability to measure CSA in nuclei with spins I > 1/2. Here we show that these two interactions can be refocused at different times in a 2D multiple-quantum NMR experiment on polycr...

The question of whether the phase cycling can still be used to select coherence transfer pathways in spin systems experiencing a tilting of its eigenstates away from the Zeeman eigenstates due to strong couplings was investigated theoretically. Based on the analysis presented it is concluded that conventional phase cycling is still a valid approach for selecting a coherence transfer pathway sig...

Nuclear quadrupole resonance (NQR) is a radio frequency spectroscopic technique that can be used to detect solidstate compounds containing quadrupolar nuclei, a requirement fulfilled by most high explosives (and narcotics). In this paper, we present an overview of recent research in the detection of explosives using this technique. We also present mathematical models for the data for different ...