ELECTRONIC-STRUCTURE OF C(84) AND K(X)C(84) - COMPARISON TO C(60) ANDGRAPHITE

X ray photoemission spectra show approximately 10 valence band feature s in C60 and C84 films, although they are less distinct in C84 because of the increased number of valence electrons and the decreased molecu lar symmetry. The presence of inequivalent carbon atoms in C84 is refl ected by the fact that the C 1s main line is approximately 0.2 eV wide r than in C60. The C 1s satellite region of C84 exhibits four features within 15 eV of the main line and shows that the HOMO-LUMO pi-pi exc itation energy of C84 is approximately 0.5 eV smaller than in C60. Pot assium 2p spectra for K-doped C84 films suggest the formation of a pha se with composition K3C84 with two spectroscopically-distinguishable K sites. A new spectral feature emerges when the K content is increased beyond K3C84, suggesting a phase transition and a saturated compositi on of K6C84, as for KxC60. These similarities are intriguing since KxC 84 is insulating for all x while K3C60 is metallic and superconducting .