Zhejiang Univ, Dept Phys, Hangzhou 310027, Peoples R China
; Acad Sinica, Inst High Energy Phys, Lab Synchrotron Radiat, Beijing 100039, Peoples R China
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 theoretical ones calculated for K3C60 at low temperature with the so-called one-dimensional disordered structure. But there is a large deviation of experimental subband intervals from the theoretical values. By considering the influence of the Coulomb energy of K+ ion and the valence electron, the deviation, at least for the order of magnitude, is interpreted. This result is meaningful for the studies of the physical properties of alkali-doped C-60 solids, e.g., the mechanism for superconductivity. Better interpretations for the experimental band dispersions demand further research work, some possible directions of which are suggested.