SOLID-STATE MAGNETIC-RESONANCE SPECTROSCOPY OF FULLERENES

We report solid-state C-13 NMR measurements on powder samples of C60 and of a mixture of C60 and C70. The NMR results show that, at 296 K, C60 molecules rotate rapidly and isotropically in the solid state, while C70 molecules rotate somewhat more anisotropically. These results are consistent with the proposed spherical geometry of C60 and prolate spheroidal geometry of C70. The rotational correlation time of C60 molecules in the solid state becomes greater than 50 mu-s at about 100 K.