A spectroscopic study of M rate at C82 metallofullerenes: Raman, far-infrared, and neutron scattering results

Polycrystalline samples of M rate at C82 metallofullerenes have been studied at room temperature by Raman (for M=La, Y, Ce, Gd), far-infrared (FIR) (for M=La, Y, Ce), and inelastic neutron scattering (INS) (for M=La, Y) spectroscopy. Raman and FIR spectra suggest that these metallofullerenes have a common dominant, if not a single, structure of the C82 cage and a similar bonding of the encapsulated metal ion, i.e. the bonding is primarily electrostatic and the metal atoms are in the same oxidation state (+3). The metal ion vibrations are located around 160 and 50 cm-1. INS reveals no gap between internal vibrational and external vibrational and rotational modes in the range ∝50-200 cm-1 as is typically observed for other fullerides and also predicted by our model calculations. Presumably this is due to strong intermolecular interactions between M rate at C82 units in the bulk sample. The studied metallofullerenes are air sensitive, and degradation in air could be followed by changes in the Raman spectra. (orig.)