Electronic structure of K doped C60 monolayers on Ag(001)

The doping of a C-60/Ag(100) interface with K is studied by high resolution valence band photoemission spectroscopy. With increasing potassium exposure the progressive filling of the C-60 lowest unoccupied molecular orbital (LUMO) derived band is observed. The charge transfer onto the C-60 molecules is quantified from the observed binding energies of the LUMO derived band. Up to a half filled LUMO Ilo rigid band shift is found. Furthermore the intensity of the highest occupied molecular orbital is not constant but shows in normal emission a pronounced dip between half and complete LUMO filling. (C) 2000 Elsevier Science B.V. All rights reserved.