M. Knupfer et al., ELECTRONIC-STRUCTURE OF K-C-60 COMPOUNDS STUDIED USING ELECTRON-ENERGY-LOSS SPECTROSCOPY, Synthetic metals, 70(1-3), 1995, pp. 1321-1324
Single phase K3C60 and K4C60 samples have been grown using vacuum dist
illation. 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-der
ived unoccupied density of states. The joint density of states near th
e Fermi level has been examined by measuring the loss function. The sp
ectra reveal a splitting of the formerly degenerate molecular levels w
hich could explain the insulating nature of K4C60.