C-13 NMR-STUDY OF ORIENTATIONAL ORDERING IN SOLID C-70

The C-13 NMR lineshapes of powdered C70 have been measured between 450 K and 50 K. A comparison of experimental and simulated lineshapes allowed for a determination of the temperature dependence of the order parameter of the orientational phase transition at T(c)=270 K and of the tilt angle between the direction of the long axis of the C70 molecules and the [ 111 ] direction in the rhombohedral phase. The results essentinally confirm the predictions of molecular dynamics calculations of Sprik, Cheny and Klein.