ELECTRONIC-PROPERTIES OF HYDROGEN-BONDED FULLERENES AND POTASSIUM FULLERIDES

Photoemission studies show that the exposure of C60 films to atomic H produced H-bonded fullerenes. Such H-C60 bonding reduced the emission from features associated with the C60 pi electrons and broadened valen ce band and C Is core-level features. It was also possible to vary the H content of the films by depositing the fullerenes in different par- tial pressures of atomic H. We show that K atoms mix with these hydrog enated films but that the resulting fullerides show substantially redu ced metallic character for small amounts of H; they are not metallic a t all at higher H content. The nonmetallic character probably results from reduced overlap between pi-derived orbitals of adjacent H-bonded fullerenes and changes in the orbitals occupied by charge transfer fro m K.