FLUORESCENCE DYNAMICS OF YVO4-TM3-TM3+, TB3+ AND YVO4-TM3+, HO3+ CRYSTALS(, YVO4)

The fluorescence dynamics of the H-3(4) and F-3(4) energy levels of Tm 3+ in YVO4 single crystals codoped or not codoped with Tb3+ and Ho3+ i ons was experimentally investigated and compared with classical energy -transfer models. In the YVO4:1% Tm3+ and YVO4:1% Tm3+, 1% Ho3+ crysta ls, the H-3(4) state relaxes predominantly by internal cross-relaxatio n-type energy transfers, whereas in the YVO4:0.5% Tm3+, 1% Tb3+ and YV O4:1% Tm3+, 1% Tb3+ crystals the relaxation is dominated by direct ene rgy transfers to the F-7(1) state of the Tb3+ ions. In all of the codo ped systems, strong energy transfers from the F-3(4) state of the Tm3 ions to the F-7(1) and I-5(7) states of the Tb3+ and Ho3+ codopants w ere evident. The electric dipole-electric dipole coupling parameter wa s evaluated for several cross-relaxation and direct-energy-transfer pr ocesses.