| Journal: | Quimica nova |
| Database: | PERIÓDICA |
| System number: | 000197757 |
| ISSN: | 0100-4042 |
| Authors: | Carlos, Luis D1 Ferreira, Rute A. Sa Bermudez, Veronica de Zea Bueno, Luciano A Molina, Celso Messaddeq, Younes Ribeiro, Sidney J.L |
| Institutions: | 1Universidade de Aveiro, Departamento de Fisica, Aveiro. Portugal 2Universidade Estadual Paulista "Julio de Mesquita Filho", Instituto de Quimica, Araraquara, Sao Paulo. Brasil 3Universidade de Tras-os-Montes e Alto Douro, Vila Real. Portugal |
| Year: | 2001 |
| Season: | Jul-Ago |
| Volumen: | 24 |
| Number: | 4 |
| Pages: | 453-459 |
| Country: | Brasil |
| Language: | Portugués |
| Document type: | Artículo |
| Approach: | Experimental |
| English abstract | Eu3+ luminescence and EXAFS (Extended X-ray Absorption Fine Structure) results are presented for organic-inorganic hybrid gel hosts composed of a siliceous network to which small chains of oxyethylene units are covalently grafted by means of urea bridges. Coordination numbers for Eu3+ ions range from 12.8 to 9.7 with increasing Eu3+ concentration while the Eu3+-first neighbours mean distance is found to be constant at 2.48-2.49 Å in the same concentration range. Emission spectra display a broad band in the green/blue spectral region superposed to narrow lines appearing in the yellow/red region in such a way that for the eyes emission appears white. The broad band is assigned to intrinsic NH groups emission and also to electron-hole recombination in the nanosised siliceous domains. The narrow lines are assigned to intra-4f6, 5D0®7F0-4 Eu3+ transitions and from the energy position of the 7F0-4 levels a mean distance could be calculated for the Eu3+-first neighbours. The calculated results are in good agreement with the experimental ones obtained from EXAFS analysis |
| Disciplines: | Química |
| Keyword: | Química organometálica, Europio, Coordinación local, Luminiscencia, Híbridos |
| Keyword: | Chemistry, Organometallic chemistry, Local coordination, Luminescence, Hybrids, Europium |
| Full text: | Texto completo (Ver HTML) |
