Effects of dispersion by Gd3+ upon europium diphenylphosphinate luminescence

A series of binary diphenylphosphinates with Eu3+ and Gd3+ were prepared. The compounds have the general formula Gd1-xEux(DPP)(3), where x ranges from 0 to 1. The spectroscopic measurements show interesting behavior. The intensity of the D-5(0) --> F-7(2) transitions decreases relative to D-5(0) --> F-7(1) With an increase in europium dispersion. Inside the temporal domain, the same decrease is observed with increasing delay after excitation. The lifetimes are also affected, which can be seen in the x = 1 compound, where the decay is a first-order process and lifetime values are 4.81 ms. In the binary compound, as an effect of dispersion, the lifetime of the D-5(0) level measured at the D-5(0) --> F-7(1) transition increases with europium dispersion, and the average along the series is 6.25 ms. The decay measured at the D-5(0) --> F-7(2) transitions reveals a second-order process with lifetimes ranging from 1.90 to 6.00 ms. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Cr3+ and Cr4+ luminescence in glass ceramic silica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of the ytterbium concentration on the upconversion luminescence of Yb3+/Er3+ co-doped PbO-GeO2-Ga2O3 glasses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A cooperative game theory analysis for transmission loss allocation

This paper presents an analysis and discussion, based on cooperative game theory, for the allocation of the cost of losses to generators and demands in transmission systems. We construct a cooperative game theory model in which the players are represented by equivalent bilateral exchanges and we search for a unique loss allocation solution, the Core. Other solution concepts, such as the Shapley Value, the Bilateral Shapley Value and the Kernel are also explored. Our main objective is to illustrate why is not possible to find an optimal solution for allocating the cost of losses to the users of a network. Results and relevant conclusions are presented for a 4-bus system and a 14-bus system. (c) 2007 Elsevier B.V. All rights reserved.

Structural and Luminescence Properties of Silica-Based Hybrids Containing New Silylated-Diketonato Europium(III) Complex

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Luminescence properties of Eu(3+)- and Mg(2+)-doped LiTaO(3) obtained via the polymeric precursor method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Luminescence of Tb(3+) doped TeO(2)-ZnO-Na(2)O-PbO glasses containing silver nanoparticles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Frequency upconversion luminescence from Yb+3-Tm+3 codoped PbO-GeO2 glasses containing silver nanoparticles

Infrared-to-visible and infrared-to-infrared frequency upconversion processes in Yb3+-Tm3+ doped PbO-GeO2 glasses containing silver nanoparticles (NPs) were investigated. The experiments were performed by exciting the samples with a diode laser operating at 980 nm (in resonance with the Yb3+ transition F-2(7/2)-> F-2(5/2)) and observing the photoluminescence (PL) in the visible and infrared regions due to energy transfer from Yb3+ to Tm3+ ions followed by excited state absorption in the Tm3+ ions. The intensified local field in the vicinity of the metallic NPs contributes for enhancement in the PL intensity at 480 nm (Tm3+ :(1)G(4)-> H-3(6)) and at 800 nm (Tm3+ : H-3(4) -> H-3(6)). (C) 2009 American Institute of Physics. [doi:10.1063/1.3211300]

Optical spectroscopy and upconversion luminescence in Nd3+ doped Ga10Ge25S65 glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stokes and anti-Stokes luminescence of Er3+ doped Ga10Ge25S65 glass excited at 980 and 532 nm

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Enhanced luminescence of Tb3+/Eu3+ doped tellurium oxide glass containing silver nanostructures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New chelate complexes of trivalent Y and lanthanides (Eu, Ho, Yb) with a triazene N-oxide: Synthesis, structural characterization and luminescence properties

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Luminescence and non-radiative processes in lanthanide squarate hydrates

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.

Crystal structures and luminescence properties of La3Zr4F25 and α-LaZr3F15

During a study of the LaF3-ZrF4 system, both La3Zr4F25 and α-LaZr3F15 compounds have been evidenced. Their crystal structures have been determined from single-crystal X-ray diffraction data. La3Zr4F25 crystallises in the cubic system with a = 12.384 Å and 143d space group (no. 220). Its crystal structure is built up of (ZrF6)2- octahedra and (LaF8)5- dodecahedra sharing corners. The low temperature form, α, of LaZr3F15 is orthorhombic (space group Pmmn, no. 59) with a = 15.721 Å, b = 16.299 Å, c = 8.438 Å. Its structure is built of corner-sharing tricaped trigonal prisms surrounding the La3+ ions and both octahedra and monocapped trigonal prisms encompassing the Zr4+ ions. This structure is characterised by dynamically disordered (ZrF6)2- complex anions. The Eu3+ luminescence properties of these phases have been investigated and are discussed in relationship with their crystal structures.