Raman scattering has been performed on pure polycrystalline ${\mathrm{C}}_{60}$ powder over a frequency range of 20–2500 ${\mathrm{cm}}^{\mathrm{-}1}$. The phonon Raman lines appearing only between 250 and 1600 ${\mathrm{cm}}^{\mathrm{-}1}$ can be assigned to all the Raman-active vibrational modes (2${\mathit{A}}_{\mathit{g}}$+8${\mathit{H}}_{\mathit{g}}$) predicted for the isolated ${\mathrm{C}}_{60}$ molecules, which suggests only minor effects of intermolecular coupling on the properties of molecular vibrations. A comparison of the spectra taken at room temperature and low temperature (150 K) shows no significant change of the vibrational Raman modes after an orientational ordering transition.

• Received 6 December 1991

DOI:https://doi.org/10.1103/PhysRevB.45.11437