Molecular dynamics, phase diagrams and electronic properties of fullerenes and alkali fullerides: insights from solid-state nuclear magnetic resonance spectroscopy.

Solid-state nuclear magnetic resonance (NMR) measurements have made important contributions to the current understanding of the structural, dynamical, and electronic properties of fullerenes (C60 and C70) and the alkali fullerides AxC60 (A = alkali metal). These measurements and their interpretation are reviewed. One- and two-dimensional 13C NMR lineshapes and spin-lattice relaxation rates provide evidence for rapid molecular rotations and orientational order-disorder transitions in the fullerenes and alkali fullerides. The kinetics of molecular reorientations are determined from the NMR data. 13C and alkali metal NMR spectra indicate that the alkali fullerides are stoichiometric compounds. Each stable, stoichiometric phase has distinctive NMR signatures. 13C and alkali metal NMR spectra and relaxation measurements provide valuable and unique information about the electronic properties of the metallic, superconducting, and non-metallic phases of the alkali fullerides.