LUMO-derived band structure of K3C60

K3C60 single-crystal film was prepared on the cleaved (111) surface of C-60 single crystal. Synchrotron radiation angle-resolved photoemission spectra were measured at normal emission with sample temperature at similar to 150 K. Up to four subpeaks of LUMO-derived bands were observed. These subpeaks exhibit distinct energy dispersions which resemble, in general, the theore tical ones calculated for K3C60 at low temperature with the so-called one-d imensional disordered structure. But there is a large deviation of experime ntal subband intervals from the theoretical values. By considering the infl uence of the Coulomb energy of K+ ion and the valence electron, the deviati on, at least for the order of magnitude, is interpreted. This result is mea ningful for the studies of the physical properties of alkali-doped C-60 sol ids, e.g., the mechanism for superconductivity. Better interpretations for the experimental band dispersions demand further research work, some possib le directions of which are suggested.