Photoemission study of K- and Sc-doped C84

The electronic structure of solid C84 with doping of K or Sc metal was studied by ultraviolet photoemission spectroscopy. Successive filling of the LUMO (lowest unoccupied molecular orbital) , LUMO+1, and LUMO+2 bands by electrons donated from doped K atoms was clearly observed in K-doped C84. In the case of Sc-doped one, no clear successive filling of unoccupied bands was observed although new electronic states appear between the HOMO (highest occupied molecular orbital) band and the Fermi level with doping. In either of K- and Sc-doped solid C84, no clear Fermi-edge cutoff indicative of its metallic nature was observed in the spectrum.