“…It should be mentioned in this point that the observed emission intensity was relatively weak in this system. The strongest band of the spectrum corresponds to the 5 D 0 → 7 F 2 transition, which is strongly hypersensitive to the surrounding of the Eu 3+ ion [19][20][21][22][23][24][25][26][27]. This transition is electric dipole allowed in contrast to the 5 D 0 → 7 F 1 transition which is purely magnetic dipole allowed.…”
Section: Luminescence Propertiesmentioning
confidence: 99%
“…This transition is electric dipole allowed in contrast to the 5 D 0 → 7 F 1 transition which is purely magnetic dipole allowed. The ratio between the integrated intensities of these transitions: I ( 5 D 0 → 7 F 2 ):I (( 5 D 0 → 7 F 1 ) = I 0-2 :I 0-1 , could serve as a probe of the covalent nature or asymmetry for the local sites of the Eu 3+ ions [19][20][21][22][23][24][25][26][27]. The change of the ratio of the I ( 5 D 0 → 7 F 4 ):I ( 5 D 0 → 7 F 1 ) = I 0-4 :I 0-1 integrated intensities upon the change of the excitation wavelength reflects the different bulk properties of the RE containing materials [21,23,24].…”
Section: Luminescence Propertiesmentioning
confidence: 99%
“…When the I 0-4 :I 0-1 ratio is considered, the values: 0.1 at 77 K (0.2 at 300 K) and 0.1 at 77 K (0.3 at 300 K) are obtained, respectively, for the 266 and 308 nm lines. The I 0-2 :I 0-1 hypersensitive ratio was related both to the covalency and the polarization of the surrounding of the Eu 3+ ion via short-range effects [20,21,[24][25][26] and the distortion of the local field around this ion [21,24,26]. The results obtained for the crystal studied here suggest that the coordination shell of the Eu 3+ ions associated with the ∼614 nm 5 D 0 → 7 F 2 transition is more covalent or more asymmetric than the coordination shell of the other site associated with the ∼619 nm transition.…”
“…It should be mentioned in this point that the observed emission intensity was relatively weak in this system. The strongest band of the spectrum corresponds to the 5 D 0 → 7 F 2 transition, which is strongly hypersensitive to the surrounding of the Eu 3+ ion [19][20][21][22][23][24][25][26][27]. This transition is electric dipole allowed in contrast to the 5 D 0 → 7 F 1 transition which is purely magnetic dipole allowed.…”
Section: Luminescence Propertiesmentioning
confidence: 99%
“…This transition is electric dipole allowed in contrast to the 5 D 0 → 7 F 1 transition which is purely magnetic dipole allowed. The ratio between the integrated intensities of these transitions: I ( 5 D 0 → 7 F 2 ):I (( 5 D 0 → 7 F 1 ) = I 0-2 :I 0-1 , could serve as a probe of the covalent nature or asymmetry for the local sites of the Eu 3+ ions [19][20][21][22][23][24][25][26][27]. The change of the ratio of the I ( 5 D 0 → 7 F 4 ):I ( 5 D 0 → 7 F 1 ) = I 0-4 :I 0-1 integrated intensities upon the change of the excitation wavelength reflects the different bulk properties of the RE containing materials [21,23,24].…”
Section: Luminescence Propertiesmentioning
confidence: 99%
“…When the I 0-4 :I 0-1 ratio is considered, the values: 0.1 at 77 K (0.2 at 300 K) and 0.1 at 77 K (0.3 at 300 K) are obtained, respectively, for the 266 and 308 nm lines. The I 0-2 :I 0-1 hypersensitive ratio was related both to the covalency and the polarization of the surrounding of the Eu 3+ ion via short-range effects [20,21,[24][25][26] and the distortion of the local field around this ion [21,24,26]. The results obtained for the crystal studied here suggest that the coordination shell of the Eu 3+ ions associated with the ∼614 nm 5 D 0 → 7 F 2 transition is more covalent or more asymmetric than the coordination shell of the other site associated with the ∼619 nm transition.…”
The mechanism of the Yb 3ϩ →Er 3ϩ energy transfer as a function of the donor and the acceptor concentration was investigated in Yb 3ϩ -Er 3ϩ codoped fluorozirconate glass. The luminescence decay curves were measured and analyzed by monitoring the Er 3ϩ ( 4 I 11/2 ) fluorescence induced by the Yb 3ϩ ( 2 F 5/2 ) excitation. The energy transfer microparameters were determined and used to estimate the Yb-Er transfer rate of an energy transfer process assisted by excitation migration among donors state ͑diffusion model͒. The experimental transfer rates were determined from the best fitting of the acceptor luminescence decay obtained using a theoretical approach analog to that one used in the Inokuti-Hirayama model for the donor luminescence decay. The obtained values of transfer parameter gamma ͓␥͑exp͔͒ were always higher than that predicted by the Inokuti-Hirayama model. Also, the experimental transfer rate, ␥ 2 (exp), was observed to be higher than the transfer rate predicted by the migration model. Assuming a random distribution among excited donors at the initial time (tϭ0) and that a fast excitation migration, which occurs in a very short time (t Ӷ␥ Ϫ2 ), reducing the mean distance between donor ͑excited͒ and acceptor, all the observed results could be explained.
“…Because linear strength of magnetic dipole transition nearly cannot be influenced by outer environment, the value of S md for a certain transition has no relation with the hosts and it is a constant. S md is calculated to be 7.83 × 10 −42 esu(c) cm 2 through the data in literature [27].…”
Section: Calculating and Quantum Efficiency Of Eu 3+ 5 D 0 Energy Levmentioning
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