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The dielectric constant [Epsilon] and conductivity Σ of undoped [C.sub.60] single crystals have been measured as a function of temperature, 10 K < T < 330 K, and frequency, 0.2 kilohertz < f < 100 kilohertz. On cooling below the first-order structural phase transition at 260 K, a Debye-like relaxational contribution to the dielectric response is observed, which requires the presence of permanent electric dipoles. The relaxation rate is thermally activated with a broad distribution of energies centered at 270 millielectron volts. The existence of a dipole moment in [C.sub.60] is unexpected, because it is precluded by symmetry for the pure ordered cubic phase. These data suggest that the high degree of frozen-in orientation disorder of the [C.sub.60] molecules for the existence of electric dipolar activity., The discovery and synthesis of the icosahedral carbon molecule [C.sub.60] [1] and its subsequent crystallization [2] have stimulated great gravity directed toward understanding the static and dynamic properties of its [...]

Sensitive experiments have been developed that search for electric dipole moments of atoms, molecules, and the neutron. These experiments play an important role in deciding which of the myriad theoretical [...]