Rotation-vibrational dynamics of solid ${\mathrm{C}}_{60}:$ A Raman study

The rotational dynamics of ${\mathrm{C}}_{60}$ fullerites has been examined by measuring the Raman-active intramolecular modes at various temperatures. The linewidth of the $H_g$ modes increases significantly upon heating from slightly below (sc phase) to room temperature (fcc phase), whereas the broadening of the $A_g$ line is much weaker. We analyze these results considering the appearance of rotational satellite bands of the $H_g$ vibrational lines above $T_c=256\mathrm{}\hspace{0.5em}\mathrm{K}.$ We also discuss small additional contributions that may arise from rotation-vibrational interactions in both the fcc and sc phases of the ${\mathrm{C}}_{60}$ fullerite.