ELECTRONIC-STRUCTURE OF HIGHLY FLUORINATED C-60

Synchrotron-radiation photoemission was used to investigate the valence bands and C Is core-level features of thin films of C60Fx, x=46+/-2. The valence-band spectra show seven distinct features and a bandwidth of approximately 12 eV. Comparison of the calculated and experimental 40-eV photoemission spectra and the C Is core-level shifts suggests that the CF bond distances are closer to those of fluoromethane than to those of icosahedral C60F60 optimized within the local-density approximation. The valence-band maximum is approximately 5 eV below the Fermi level E(F), indicating that C60F46+/-2 is a wide-band-gap insulator. The deposition of potassium atoms on these fluorinated C60 films results in the partial removal of fluorine to form KF.