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- Luminescence and non-radiative processes in lanthanide squarate hydrates
- Universidade Federal de Pernambuco (UFPE)
- Universidade Estadual Paulista (UNESP)
- Debye Institute-Universiteit Utrecht
- The luminescence properties of solid hydrated lanthanide squarates (Ln2(C4O4)3(H2O) x; x = 8 or 13;Ln3+ = Gd, La, Eu, Tb, Pr) are reported for temperatures down to 4.2K. The luminescence of the squarate group is observed for the Gd3+ and La3+ compounds at low temperatures (below 150K). The Pr3+ compound does not show any emission at all, not even at 4.2K. This is ascribed to the quenching of the Pr3+ emission by multiphonon relaxation and/or concentration quenching. The quantum efficiencies of the 5D0 emission of Eu3+ and of the 5D4 emission of Tb3+ in these squarate complexes are strikingly different. Whereas the Tb3+ emission shows a temperature independent quantum efficiency of 50% upon ligand excitation, the Eu3+ emission is strongly quenched, showing a temperature dependent quantum efficiency of 0.8% at 4.2K upon ligand excitation. This quenching is ascribed to the low energy position of the charge-transfer state of Eu3+ in these compounds.
- Journal of Physics and Chemistry of Solids, v. 57, n. 11, p. 1727-1734, 1996.
- A. inorganic compounds
- D. luminescence
- D. optical properties
- Charge transfer
- Optical properties
- Quantum efficiency
- Concentration quenching
- Lanthanide squarate hydrates
- Ligand excitation
- Multiphonon relaxation
- Nonradiative processes
- Rare earth compounds
- Acesso restrito
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