Optical properties of Cu nanoclusters supported on MgO(100)
| Autor: | Francesc Illas, Gianfranco Pacchioni, Carmen Sousa, Annalisa Del Vitto |
|---|---|
| Přispěvatelé: | DEL VITTO, A, Sousa, C, Illas, F, Pacchioni, G |
| Rok vydání: | 2004 |
| Předmět: |
Pel·lícules fines
Defectes cristal·lins Optical properties Chemistry Band gap supported clusters DFT calculations Thin films General Physics and Astronomy Crystals defects Crystallographic defect Molecular physics Nanoclusters Ab initio quantum chemistry methods Espectroscòpia de pèrdua d'energia d'electrons Cluster (physics) Physics::Atomic and Molecular Clusters Density functional theory Physical and Theoretical Chemistry Thin film Atomic physics Electron energy loss spectroscopy Propietats òptiques Surface states |
| Zdroj: | Dipòsit Digital de la UB Universidad de Barcelona |
| ISSN: | 0021-9606 |
| Popis: | 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. (C) 2004 American Institute of Physics. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|