Photoelectron spectra of higher fullerenes and their potassium complexes

Ultraviolet photoelectron spectra of higher fullerenes, C76, C78, C82, C84 and C96 have been measured with a synchrotron radiation light source. When the number of the carbon atoms increases, the spectral onset moves toward the Fermi level. The spectral structures above 5 eV are characteristic to each fullerene. The structures below 5 eV resemble, which indicates the analogous electronic structures of the fullerene carbon cages. When potassium is dosed onto higher fullerenes, a structure appears between the spectral onset and the Fermi level. This is the result of the transfer of the K 4s electron to the lowest unoccupied molecular orbital of higher fullerenes. The spectral onset of potassium dosed higher fullerenes does not cross the Fermi level at any potassium content, which suggests their semiconductive nature.