BENZENE-SOLVATED C-60-H-1 NUCLEAR-SPIN-LATTICE MAGNETIC-RELAXATION

Crystalline C-60.4C(6)H(6) was studied by NMR. Using a saturation-reco very method, the spin-lattice relaxation time, T-1, of the protons of benzene was measured as a function of temperature between 4 K and 300 K. The H-1 data were fitted by a model where four correlation times ar e present. They correspond to thermally activated processes which foll ow an Arrhenius law: the activation energies are, respectively, 60 K, 279 K, 1365 K and 2945 K. All constituents of our system are extremely mobile and no structural phase transitions are observed near 260 K an d 90 K as in the case of pure C-60 crystals. We have also studied the temperature dependence of the H-1 NMR linewidth which narrows with inc reasing temperature. (C) 1998 Elsevier Science Ltd.