Photoelectron spectra of metallofullerenes, GdC₈₂ and La₂C₈₀: Electron transfer from the metal to the cage

Ultraviolet photoelectron spectra of metallofullerenes, GdC₈₂ and La₂C₈₀ were measured with synchrotron orbital radiation. The specimens were dried-up films prepared from their solution instead of the sublimed films commonly adopted for the measurement. GdC₈₂ gave structure rich spectra reflecting its electronic structure. The band intensity of the GdC₈₂ spectra depends on the incident photon energy, as observed in other fullerenes. The similarity of the GdC₈₂ spectra to those of LaC₈₂ indicates that their electronic structures are analogous. The spectrum of La₂C₈₀ does not show any characteristic structures that have been observed in those of other fullerenes, and it resembles that of amorphous carbon. The C ls core photoelectron spectra of these metallofullerenes obtained with the Mg Kα radiation are also presented.