Ultraviolet photoelectron spectra of mono metal atom encapsulated fullerenes

Ultraviolet photoelectron spectra of mono metal atom encapsulated fullerene s, M@C-82 (M = La, Gd and Sc), are measured with a synchrotron radiation li ght source. When the excitation energy is tuned, spectral intensity oscilla tion is observed in these mono metal atom encapsulated fullerenes as was in empty fullerene, C-82. Their incident photon energy dependence is essentia lly the same. Their spectra deeper than 5 eV are almost identical and are s imilar to those of empty fullerene. The noticeable difference among the spe ctra is in the energy region between the Fermi level and 4 eV, which reveal s the degree of electron transfer from the metal atom to the fullerene cage .