SOLID C-76 - NMR-STUDIES OF MOLECULAR-DYNAMICS

Static susceptibility and C-13 NMR studies on solid C-76 are reported. The molecular dynamics of C-76 in the solid phase was found to be str ongly affected by the purification process, showing a different manner from those in solid C-60 and C-70 For the sublimed C-76, the C-13 NMR spectra indicate that quasi-isotropic molecular rotation exists above similar to 140 K in the time scale of 20 mu s. Above 170 K, the rotat ional correlation time obeys an Arrhenius law tau=tau(0)exp[T-0/T] wit h tau(0)=1.8 psec and T-0=1350 K. However, an orientational ordering t ransition or glassy phase transition was found to take place around 13 5-170 K. Static magnetic susceptibility was also determined as -7.16+/ -0.10 cgs ppm per mole of carbon at 300 K.