High-resolution photoemission study of the valence-band electronic str
ucture of A(x)C(60) (A = K or Cs; x less than or similar to 3) close t
o EF reveals a phase separation into components exhibiting a dilute so
lid solution of alkali in fullerite (alpha-C-60) and A(3)C(60). The al
pha-C-60 phase is found to be remarkably stable against oxidation. Our
analysis shows a strongly correlated electronic system in this phase.
The similarity of the present data to previously published results fo
r Li-, Na- and Rb-doped C-60 demonstrates the common character of the
observed phenomena for this series of alkali-doped fullerites.