The electronic structure of small chromium clusters deposited by evaporation onto clean polycrystalline graphite has been studied by means of the Electron Energy Loss (EELS), Auger and X-ray photoemission (XPS) spectroscopies. The XPS results show an increase of the binding energy of both core levels and 3d valence band states when the cluster size decreases. The analysis of the Auger spectra by the Cini-Sawatzky theory suggests that the electronic screening properties do not change in small clusters with respect to the bulk. The EELS spectra indicate an increase of the energy loss features due to the interband transitions between 3d full states and sp empty states when the cluster size decreases. These observations are attributed to sizeable changes occurring in the electronic structure of the clusters.
XPS, AES AND EELS STUDIES OF CR CLUSTERS ON GRAPHITE
LOZZI, Luca;PASSACANTANDO, MAURIZIO;SANTUCCI, Sandro;
1993-01-01
Abstract
The electronic structure of small chromium clusters deposited by evaporation onto clean polycrystalline graphite has been studied by means of the Electron Energy Loss (EELS), Auger and X-ray photoemission (XPS) spectroscopies. The XPS results show an increase of the binding energy of both core levels and 3d valence band states when the cluster size decreases. The analysis of the Auger spectra by the Cini-Sawatzky theory suggests that the electronic screening properties do not change in small clusters with respect to the bulk. The EELS spectra indicate an increase of the energy loss features due to the interband transitions between 3d full states and sp empty states when the cluster size decreases. These observations are attributed to sizeable changes occurring in the electronic structure of the clusters.Pubblicazioni consigliate
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