Electron-diffraction and photoelectron-spectroscopy studies of fullerene and alkali-metal fulleride films.

Photoelectron spectroscopy and low-energy electron diffraction (LEED) have been used to examine the electronic structure and crystallinity of thin films of A X C 60 where A=Na, K, Rb, and Cs and 0≤x≤6. For undoped C 60 films, temperature-dependent LEED studies show changes that correspond to the lattice transformation from the simple-cubic to the face-centered-cubic structure. For doped C 60 films, the LEED results show a decrease in the quality of the LEED pattern upon the nucleation of the body-centered A-C 60 phases. Spectroscopic studies of these fullerides indicate that the effects of electron correlation are always important