Luminescence and absorption of Sn-related impurity centers in silica.

ABSTRACT We report an experimental study on the absorption and luninescence spectra of oxygen deficient point defects in Sn-doped silica. The absorption band at 4.9 eV (B2b band) and the two related photoluminescence bands at -4.2 eV (singlet-singlet emission, S1 -> So) and at 3.2 eV (triplet-singlet emission, T1 -> So), linked by a thermally activated T1 -> S1 inter-system crossing process (ISC), are studied as a function oftemperature from 300 to 20 K. This approach allows us to investigate the dynamics properties of the matrix in the surroundings of the point defects and the efects of local disorder on the two relaxation processes from S1: the radiatiye channel to So and the ISC process …