Electronic and geometric structure of thin CoO(100) films studied by angle-resolved photoemission spectroscopy and Auger electron diffraction

We have prepared ordered thin films of CoO by evaporating cobalt in an O-2 atmosphere on to a heated (500 K) Ag(100) substrate. The geometric and elec tronic structure of the films was characterized by means of Auger electron diffraction (AED) and angle-resolved photoemission spectroscopy (ARUPS), re spectively. The experimental AED results were compared with simulated data, which showed that the film grows in (100) orientation on the Ag(100) subst rate. Synchrotron-radiation-induced photoemission investigations were perfo rmed in the photon energy range from 25 eV to 67 eV. The dispersion of the transitions was found to be similar to that of previous results on a single -crystal CoO(100) surface. The resonance behaviour of the photoemission lin es in the valence-band region was investigated by constant-initial-state (C IS) spectroscopy. The implications of this behaviour for assignment of the photoemission lines to specific electronic transitions is discussed and com pared with published theoretical models of the electronic structure. (C) 20 00 Elsevier Science B.V. All rights reserved.