MOLECULAR AND INTRAMOLECULAR DYNAMICS OF A C-80 DIMETALLOFULLERENE

Molecular and intramolecular dynamics of solid-state CeLa@C-80 has bee n studied based on time-differential perturbed-angular-correlation (TD PAC) measurements by employing the Ce-140 nucleus, a beta(-) decay pro duct of La-140, as the probe. Rotational motion of the molecules was s uggested by the temperature dependence of the reorientational correlat ion time of electric quadrupole interaction tau(c), which abruptly cha nges at approximately 160 K, implying the freezing of the motion. The dynamic motion of the Ce atom was observed even below that temperature , down to 40 K, and all of the motions causing dynamic perturbation on the nucleus vanish at further low temperatures. Some intrinsic nature of the interactions among and within the fullerene molecules, CeLa@C- 80, is also discussed in comparison with Ce@C-82, based on physical pa rameters obtained by the TDPAC method. [S0163-1829(98)09639-8].