No abstract

No abstract

No abstract

No abstract

No abstract

Absorption and emission properties and fluorescence lifetimes for the [Formula: see text] transition of Nd(3+) ions embedded in P(2)O(5)-K(2)O-MgO-Al(2)O(3) (PKMA)-based glasses modified with AlF(3) and BaF(2) are reported at room temperature. The observed energy levels of Nd(3+) ions in these glasses have been analysed through a semi-empirical free-ion Hamiltonian model. The spin-orbit interaction and net electrostatic interaction experienced by the Nd(3+) ions follow the trend as PKMA>PKMA+AlF(3)> PKMA+BaF(2) glasses. Judd-Ofelt analysis has been carried out on the absorption spectra of 1.0 mol% Nd(3+)-doped glasses to predict the radiative properties for the fluorescent levels of the Nd(3+) ion. Branching ratios and stimulated emission cross-sections show that the [Formula: see text] transition of the glasses under investigation has the potential for laser applications. The Inokuti-Hirayama model has been applied to investigate the non-radiative relaxation of the Nd(3+) ion emitting state, (4)F(3/2). Based on the decay curve analysis, concentration quenching of the (4)F(3/2) emission has been attributed to a cross-relaxation process between the Nd(3+) ions.

No abstract

Fluorescence spectra and decay curves for the 5 D 4 → 7 F 5 transition of Tb 3+ ions in 59TeO 2 -20ZnO-20LiF-1Tb 4 O 7 (TZLFTb) glass have been measured and analysed as a function of pressure up to 14.9 GPa at room temperature. In this pressure range, the red shift for the band positions of 5 D 4 → 7 F 3 , 7 F 4 and 7 F 5 is found to be 3.2, 3.2 and 2.2 cm −1 GPa −1 , respectively, which could be attributed to an expansion of the 4f electron wavefunctions with increasing covalency. There is also a considerable pressure effect on the magnitude of the crystalfield splittings observed in the 7 F 4 and 7 F 5 transitions, which increases with pressure because of Coulomb interactions between the 4f electrons and their ligands. In addition, the decay curve is found to be perfectly single exponential at ambient pressure, and turns into a non-exponential with increasing pressure. The non-exponential decay curves at higher pressures are well fitted to the Inokuti-Hirayama model for S = 6, which indicates that the energy transfer between the donor and acceptor is of dipole-dipole nature. The decrease in the lifetime with increasing pressure is caused by an increase in the electronic transition probabilities, which is a result of the enhanced crystal-field strength around the Tb 3+ ions. The results obtained after release of pressure show that local environment changes of the Tb 3+ ions are reversible.