Electronic structure of tbe conduction bands of K/sub 60/C/sub 60/

Summary form only given. The electronic structure of K/sub 60/C/sub 60/ has been studied by electron energy-loss spectroscopy (EELS) in transmission and by high resolution photoemission (PES). Here we focus on the half filled conduction band derived from the LUMO band of /C/sub 60/. In EELS, the partial filling of this band is directly observed in the Cls core-level excitations, and the collective excitation of the charge carriers (the plasmon) is seen near 0.5 eV. In contrast to what is expected from LDA calculations, this charge carrier plasmon shows very little dispersion as a function of the momentum transfer. The PES spectra give not only information on the conduction band density-of-states of K/sub 60/C/sub 60/, but also on the coupling of the charge carriers to phonons, which is compared to theoretical models. However, such models are unable to account for the observed anomalously large temperature dependence of the K/sub 60/C/sub 60/ conduction band spectral weigth in PES.