Photoelectron spectra of metal fullerenes: Are metal fullerenes molecular crystals or not?

Ultraviolet photoelectron spectra (UPS) of GdC82 and La2C80 were measured using synchrotron radiation. The specimens for the measurement were not evaporated films but drying up films obtained from the metal fullerene solutions. Although the effect of the contamination to the specimens remains even after heat treatment, the UPS of the GdC82 film show several characteristic structures that are essentially identical to those of LaC82. This suggests that the interaction between the GdC82 molecules are small and GdC82 Can be treated as a molecular crystal, The spectrum of La2C80 differs from those of other fullerenes, which indicates either that the interaction among the La2C80 molecules are too large to give a sharp spectrum or that the molecule does not have so-called cage structure.