C-REDOR: rotational echo double resonance under very fast magic-angle spinning

We propose a heteronuclear dipolar interaction recoupling scheme based on the pulse symmetry POST-CNnν. Numerical simulations showed that POST-C331 and POST-C771 are suitable for the characterization of heteronuclear dipolar couplings for multiple-spin systems under very fast magic-angle spinning condition. These new pulse symmetries are superior to the rotational echo double resonance method and other recoupling schemes as far as the interference of homonuclear dipolar interaction is concerned. The experiment was carried out for fluorapatite at a spinning frequency of 25 kHz and the results were in good agreement with X-ray data.