Analysis of cross relaxation between Tm3+ ions in PbO-Bi2O3-Ga2O3-GeO2 glass

Mechanisms of cross relaxation (H-3(4), H-3(6)-->F-3(4), F-3(4)) in Tm3+-doped PbO-Bi2O3-Ga2O3-GeO2 glass were analyzed. The energy gap between the absorption (H-3(6)-->F-3(4)) and emission (H-3(4)-->F-3(4)) spectra was approximately 600 cm(-1). A large decrease in cross relaxation rates at low temperatures indicated that cross relaxation is controlled by a phonon-assisted energy transfer. The bending vibration of the Ga-O-Ga bonds between GaO4 tetrahedra (similar to550 cm(-1)) was directly responsible for this energy transfer. Although GeO2 was added to enhance the thermal stability of PbO-Bi2O3-Ga2O3 glass, the phonon mode associated with vibration of GeO2 (similar to770 cm(-1)) was not involved in the cross relaxation process. (C) 2003 American Institute of Physics.