Double-quantum-filtered nuclear magnetic resonance spectroscopy applied to quadrupolar nuclei in solids

Abstract

A double-quantum filtered nuclear magnetic resonance experiment is applied to half-integer quadrupolar nuclei in solids. Filtering through a double-quantum coherence excited in a dipolar-coupled two-spin system allows spatial correlations between spins to be determined. Theoretical and experimental investigations have been carried out to optimize the excitation of double-quantum coherence between the central transitions of two neighboring nuclei while minimizing double-quantum excitation on each individual spin. The presence of the large quadrupolar coupling in the systems under study allows multiple-quantum excitation via the dipolar coupling between two spins even under conditions of magic-angle spinning, without the need for a recoupling sequence. Two-dimensional double-quantum-filtered correlation spectra have been recorded on Na23 (I=32) for Na2ZrO3 which contains three distinct Na23 sites.