Uppsala Univ Dept Phys Box 530 S-75121 Uppsala Sweden
Max Planck Inst Festkorperforsch D-70569 Stuttgart 80 Germany

Comparison of valence-photoelectron to Auger-electron spectra has been carried out fbr three phases of KxC60, x = 0, 3, 6, yielding Hubbard correlation energies, U, of 1.4 eV (1.5 eV) for x =0 (6), consistent with the results of Lof et al. [Phys. Rev. Lett. 68, 3924 (1992)]. At x = 3 the results are best described by intermolecular charge-transfer screening of the C Is core hole in the Auger initial state, with U of the same magnitude as for x = 0 and 6.
 

Physical Review B, 48 18296-18299, 1993.