Ultrafast Magic Angle Spinning Nuclear Magnetic Resonance

Recent advances in magic angle spinning (MAS) now allow spinning frequencies of 40 to 110 kHz to be reached. Ultrafast MAS is achieved in rotors with diameters smaller than around 2 mm that produce larger B-1 fields for the same amplifier output. Ultrafast MAS has considerably improved the quality of NMR spectra for a large number of samples containing spins with large anisotropic interactions. Paramagnetic samples, fully protonated compounds, or quadrupolar nuclei benefit from being studied at ultrafast MAS rates, as spinning sidebands are more separated, homogeneous interactions are reduced, and coherence lifetimes may be increased. However, as recoupling strategies developed for usual spinning speeds sometimes fail at higher speeds, new methods have successfully been developed to promote magnetization transfer and record correlation spectra.