Molecular dynamics of C70S48: Dielectric function and NMR study

Molecular dynamics of C70S48 have been studied by dielectric relaxation spe ctroscopy and NMR. In accordance with the NMR data, the rotation of C-70 mo lecules is not hindered by sulfur, and even at room temperature, it is unia xial like that in pure C-70. Numerous phase transitions observed for pure C -70 have no analogues in C70S48. The only anomaly of the dielectric functio n was found at 245 K. In accordance with the NMR data, C-70 molecules rotat e uniaxially at room temperature, but below 170 K, this rotation begins to freeze, and at 150 K, the rotation is frozen in the NMR scale. Dielectric f unction temperature dependence does not show any anomalies around 170 K, wh ere the NMR registered a freezing of the rotational freedom of C-70 molecul es, and the NMR does not show any features around 245 K, when the dielectri c function shows a sharp anomaly. Some possible explanations for the nature of the anomaly around 245 K are discussed.