ULTRAVIOLET PHOTOELECTRON-SPECTRA OF C84 AND KXC84

Ultraviolet photoelectron spectra of C84, one of the fullerene family compounds, and of potassium-dosed C84 have been measured with synchrotron radiation. The spectra of C84 are compared with those of C60 and C70. The photoemission spectral onset of C84 is 1.3 eV below the Fermi level, which is smaller by 0.5 eV than that Of C60 or C70. This indicates its small band gap, which was expected from its absorption spectra. Upon potassium dosing, a new band becomes distinct between the Fermi level and the highest occupied molecular orbital band. The new band edge does not cross the Fermi level, which indicates that potassium-dosed C84 is not metallic but a semiconductor.