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Title: Optical properties of Cu nano-clusters supported on MgO(100)
Author: Del Vitto, Annalisa
Sousa Romero, Carmen
Illas i Riera, Francesc
Pacchioni, Gianfranco
Keywords: Espectroscòpia de pèrdua d'energia d'electrons
Pel·lícules fines
Propietats òptiques
Defectes cristal·lins
Electron energy loss spectroscopy
Thin films
Optical properties
Crystals defects
Issue Date: 1-Oct-2004
Publisher: American Institute of Physics
Abstract: The vertical transitions of Cu atoms, dimers, and tetramers deposited on the MgO surface have been investigated by means of ab initio calculations based either on complete active space second-order perturbation theory or on time-dependent density functional theory. Three adsorption sites have been considered as representative of the complexity of the MgO surface: regular sites at flat (100) terraces, extended defects such as monoatomic steps, and point defects such as neutral oxygen vacancies (F or color centers) The optical properties of the supported Cu clusters have been compared with those of the corresponding gas-phase units. Upon deposition a substantial modification of the energy levels of the supported cluster is induced by the Pauli repulsion with the substrate. This causes shifts in the optical transitions going from free to supported clusters. The changes in cluster geometry induced by the substrate have a much smaller effect on the optical absorption bands. On F centers the presence of filled impurity levels in the band gap of MgO results in a strong mixing with the empty levels of the Cu atoms and clusters with consequent deep changes in the optical properties of the color centers. The results allow to interpret electron energy loss spectra of Cu atoms deposited on MgO thin films.
Note: Reproducció del document publicat a:
It is part of: Journal of Chemical Physics, 2004, vol. 121, num. 15, p. 7457-7466
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ISSN: 0021-9606
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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