Abstract

We present structural and optical properties of silver clusters Ag-n (n=2, 4, 6, 8) at two model support sites of MgO, stoichiometric MgO(100) and F-S-center defect, based on density functional theory and embedded cluster model. Our results provide the mechanism responsible for the absorption and emission patterns due to the specific interaction between the excitations within the cluster and the support site which is strongly cluster size and structure dependent. We propose Ag-4 at stoichiometric site as well as Ag-2, Ag-4 and Ag-6 at F-S-center defects as good candidates for the emissive centers in the visible regime.