Cross-Polarization, Relaxation Times and Spin-Diffusion in Rotating Solids

The cross-polarization technique in conjunction with sample spinning has been widely applied in high-resolution solid-state NMR studies. The present article reviews the major work performed during the last decade concerning the basic physical background and experimental intricacies of cross-polarization in rotation solids. The main focus is directed towards Hartmann-Hahn cross-polarization and nuclear spin systems containing spin-1/2 nuclei. However, in the introductory part a brief account is given regarding stutdies on quadrupolar nuclei and NMR techniques employing cross-polarization schemes and sample spinning with these nuclear species.