EVIDENCE FOR INCOMPLETE CHARGE-TRANSFER AND LA-DERIVED STATES IN THE VALENCE BANDS OF ENDOHEDRALLY DOPED LA-AT-C-82

Photoelectron spectra from sublimed layers of chromatographically sepa rated La@C-82 are presented. Using photon energies corresponding to th e La 3d to 4f transition, a resonant enhancement of the La-derived val ence states is observed. From the calculated resonant intensities of L a 5d and 5p states in a La atom we estimate that about 1/3 of an elect ron charge is left in the La-valence orbitals for La@C-82. In contrast to previous interpretations of La core-level photoemission studies ou r results demonstrate that the La valence electrons are not completely delocalized on the fullerene cage.