Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9778019 | Journal of Non-Crystalline Solids | 2005 | 5 Pages |
Abstract
We report a comparative study on the optical activity of surface and interior Ge-oxygen deficient centers in pressed porous and sol-gel Ge-doped silica, respectively. The experimental approach is based on the temperature dependence of the two photoluminescence bands at 4.2 (singlet-singlet emission, S1 â S0) and 3.1 eV (triplet-singlet emission, T1 â S0), excited within the absorption band at about 5 eV. Our data show that the phonon assisted intersystem crossing process, linking the two excited electronic states, is more effective for surface than for interior centers in the temperature range 5-300 K. For both centers, a distribution of the activation energies of the process is found. Based on the results of quantum chemical calculations of the electronic structure of (HO)2Ge: molecule it is suggested that the electronic de-excitation pathway involves two excited triplet states (S1 â T2 â T1 â S0) and shows a structural dependence on the O-Ge-O angle.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
A. Cannizzo, S. Agnello, S. Grandi, M. Leone, A. Magistris, V.A. Radzig,