Perspectives on high-field and solid-state NMR methods of quadrupole nuclei.

• A (S + 1/2) loss in many correlation and polarization-transfer experiments of quadrupole nuclei S. • Level-crossings of satellite transition and rf frequency under MAS complicate the spin dynamics of quadrupole nuclei. • NMR method development, high magnetic fields, efficient and high-power probes are important to quadrupole nuclei. High magnetic field can dramatically increase the spectral resolution and sensitivity of quadrupole nuclei S > 1/2 by the reduction of the second-order quadrupole broadening. A brief overview and outlook on spectral acquisition, the importance of high magnetic field, inter-nuclei distance measurement, various 2D separation and correlation methods of quadrupole nuclei are presented. The complications and consequences of spin dynamics under rf irradiation for the (2S + 1) level system and level-crossing with the satellite transition frequencies under magic-angle spinning are discussed. There is a scaling down of (S + 1/2) to the efficiency of many experiments in comparison with a spin-1/2 due to the fact that only two central transition spin states out of the (2S + 1) levels contribute to polarization transfer and spin correlation. [ABSTRACT FROM AUTHOR]