Journal of Physical Chemistry B, Vol.105, No.6, 1162-1167, 2001
Molecular dynamics of C70S48: Dielectric function and NMR study
Molecular dynamics of C70S48 have been studied by dielectric relaxation spectroscopy and NMR. In accordance with the NMR data, the rotation of C-70 molecules is not hindered by sulfur, and even at room temperature, it is uniaxial 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 function was found at 245 K. In accordance with the NMR data, C-70 molecules rotate 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 function temperature dependence does not show any anomalies around 170 K, where the NMR registered a freezing of the rotational freedom of C-70 molecules, and the NMR does not show any features around 245 K, when the dielectric function shows a sharp anomaly. Some possible explanations for the nature of the anomaly around 245 K are discussed.