Triple-quantum MAS-NMR of quadrupolar nuclei.

From two-dimensional multiquantum NMR spectra of quadrupolar nuclei, it is now possible to obtain much greater resolution than in a classical single-quantum magic-angle spinning or variable-angle spinning spectrum. We describe here a very simple pulse scheme which efficiently excites the desired multiquantum NMR coherence and a new acquisition procedure which yields to pure-absorption mode 2D spectra. Experimental spectra for 87Rb in polycrystalline rubidium nitrate illustrate the method.