ELECTRONIC-STRUCTURE OF K-C-60 COMPOUNDS STUDIED USING ELECTRON-ENERGY-LOSS SPECTROSCOPY

Single phase K3C60 and K4C60 samples have been grown using vacuum distillation. The electronic structure of these compounds has been studied using electron energy-loss spectroscopy and is compared to that of C-60 and K6C60. C1s core level excitation measurements yield the C2p-derived unoccupied density of states. The joint density of states near the Fermi level has been examined by measuring the loss function. The spectra reveal a splitting of the formerly degenerate molecular levels which could explain the insulating nature of K4C60.