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1.
Binuclear rare earth complexes Ln2L3phen2 (LnIII?=?NdIII, SmIII, EuIII, TbIII, DyIII, YbIII and YIII) with bis-CAPh type ligand - tetramethyl N,N′-(2,2,3,3,4,4-hexafluoro-1,5-dioxopentane-1,5-diyl)bis(phosphoramidate) (H2L) and 1,10-phenanthroline (phen) were synthesized and characterized by elemental analysis, IR, NMR, absorption and luminescence spectroscopy. Luminescence measurements were performed for all the complexes in solid state and for the EuIII, TbIII and YIII complexes - in solution in DMSO as well. The effective energy transfer from organic ligands to LnIII ions strongly sensitizes the LnIII ions emission and under excitation by UV light, the complexes exhibited bright characteristic emission of lanthanide metal centers. It was found that the energy level of the ligands lowest triplet state in the complexes matches better to resonance level of EuIII rather than TbIII ion. Depending on temperature the emission decay times of solid europium and terbium complexes were in the range of 1.5–2.0 ms. In solid state at room temperature the EuIII complex possess intense luminescence with very high intrinsic quantum yield 91% and decay time equal 1.88 ms. 相似文献
2.
Two novel luminescent temperature-sensitive poly(N-isopropylacrylamide) hydrogels fabricated with rare earth (Eu, Tb) picolinic acid complexes were in-situ synthesized within the interpenetration networks. Fluorescence spectra indicate the two functional gels exhibit red for Eu 3+ species and green emissions for Tb 3+ ones, respectively, whose luminescence intensities are changed due to temperature increasing from 5 to 30°C until totally quenched at lower critical solution temperature (33°C). In addition, the decreasing luminescence behavior obeys the simple linear equations. The releasing experiment substantiates that there may be complexation between O⩵C–NH⩵ moieties of P-NIPAA and Eu 3+ ions for the prolonged released time. 相似文献
3.
The luminescent properties of hybrid nanostructures constructed from colloidal quantum dots (QDs) of CdS passivated with thioglycolic acid, europium(III) tris(tenoyltrifluoroacetonate), and methylene blue dye molecules are studied. Spectral features typical for the formation of core/shell QDs of the CdS/CdS:Eu 3+ type are found. It is noted that the adsorption of the europium complex at the QD interfaces and the formation of QDs of the CdS/TGA/Eu 3+ are probable. Spectral patterns that reveal nonradiative energy transfer from the recombination luminescence centers of CdS QDs to the Eu 3+ ions in the CdS/CdS:Eu 3+ and CdS/TGA/Eu 3+ structures are obtained. This is manifested in quenching the recombination luminescence of QDs and in the ignition of the intracentric luminescence of Eu 3+, which enhance with an increase in the concentration of the europium complex. When such structures are combined with methylene blue molecules, the half-width of the absorption spectra is found to increase by 10–15% with an unchanged position of the absorption band maximum. With an increase in the concentration of methylene blue molecules, decreases in the intensity of the recombination luminescence band of CdS QDs at a wavelength of 530 nm and in the luminescence intensity of Eu 3+ ions and simultaneously the rise up of the fluorescence of methylene blue at a wavelength of about 675 nm are observed. At the same time, a decrease in the luminescence lifetime of the bands of QDs and europium ions are observed. It is concluded that the nonradiative excitation energy transfer from both the recombination luminescence centers and Eu 3+ ions to methylene blue molecules takes place. 相似文献
4.
Some novel kinds of hybrid phosphors were assembled with lanthanum (Tb, Eu, Dy) complexes (with four kinds of terbium complexes is 2,4-dihydroxybenzonic acid (DHBA), 1,10-phenanthroline (phen), acetylacetone (AA) and nicotinic acid (Nic), respectively) doped ZnO/PEG particles by co-precipitation approach derived from Zn(CH 3COO) 2 (Zn(AC) 2), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f-f transitions of Tb 3+, Eu 3+, Dy 3+ were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices. 相似文献
5.
The nature of the complexes formed between Tb 3+ and L-histidine was investigated by making use of the fact that electronic energy can be absorbed by Tb 3+/HIS complexes and subsequently transferred in a non-radiative manner to Eu 3+/HIS complexes. The transfer was found to depend on the possible association of donor and quencher, and this information was used to outline the conditions under which the histidine complexes were found to self-associate. Supplementary information was obtained from measurements of the pH dependence of Tb 3+ luminescence and differential absorbance spectra of Ho 3+/HIS complexes. At low pH, the energy transfer occurred primarily by collisional means (implying the presence of monomeric complexes), whereas the transfer was governed by the formation of associated complexes at high pH. 相似文献
6.
In this paper, Eu 3+ β-diketone Complexes with the two ligands 1-(2-naphthoyl)-3, 3, 3-trifluoroacetonate (TFNB) and 2’2-bipyridine (bpy) have
been synthesized. Furthermore, we reported a systematical study of the co-fluorescence effect of Eu(TFNB) 3bpy doped with inert rare earth ions (La 3+, Gd 3+ and Y 3+) and luminescence ion Tb 3+. The co-luminescence effect can be found by studying the luminescence spectra of the doped complexes, which means that the
existence of the other rare earth ions (La 3+, Y 3+, Gd 3+ and Tb 3+) can enhance the luminescence intensity of the central Eu 3+, which may be due to the intramolecular energy transfer between rare earth ions and Eu 3+. The efficient intramolecular energy transfer in all the complexes mainly occurs between the ligand TFNB and the central
Eu 3+. Full characterization and detail studies of luminescence properties of all these synthesized materials were investigated
in relation to co-fluorescence effect between the central Eu 3+ and other inert ions. Further investigation into the luminescence properties of all the complexes show that the characteristic
luminescence of the corresponding Eu 3+ through the intramolecular energy transfers from the ligand to the central Eu 3+. Meantime, the differences in luminescence intensity of the 5D 0→ 7F 2 transition, in the 5D 0 lifetimes and in the 5D 0 luminescence quantum efficiency among all the synthesized materials confirm that the doped complex Eu 0.5Tb 0.5(TFNB) 3bpy exhibits higher 5D 0 luminescence quantum efficiency and longer lifetime than the pure Eu(TFNB) 3bpy complex and other materials. 相似文献
7.
We report here the enhanced luminescence of Eu(III)-anchored porous anodic alumina prepared by self-assembling Eu(III) acetylacetonate, and investigate the luminescence mechanisms. Porous anodic alumina can emit visible light due to a lot of oxygen vacancies formed in the anodic oxidation. The existence of oxygen vacancies resulted in e ?-h + pairs when excited. Eu(II) exists stably by forming Eu 2+-hole complexes. The enhanced luminescence of Eu(III)-anchored porous anodic alumina is attributed to the complex luminescence of e ?-h + through luminescence center Eu 2+. 相似文献
8.
A novel co-luminescence system based on the formation of a complex between europium (III) (Eu 3+) and gatifloxacin (GFLX) in sodium dodecylbenzene sulfonate (SDBS) micelle solution containing lanthanum (III) (La 3+) has been developed for the determination of Eu 3+. The experimental results show that the complex formed by Eu 3+ and GFLX here can emit the characteristic luminescence of Eu 3+. With the addition of La 3+, the luminescence intensity of the system was enhanced about 7-fold compared with that without La 3+. Under the optimal conditions, the luminescence intensity exhibits an excellent linear relationship with Eu 3+ concentration in the range of 1.0×10 −10-5.0×10 −8 mol L −1. The correlation coefficient ( r) is 0.9998, and the detection limit (3 σ) is 7.0×10 −14 mol L −1. A test method with satisfactory accuracy based on this system was applied to determine trace amounts of Eu 3+ in rare earth samples. In addition, the detailed luminescence mechanism of this system was investigated by analyzing the ultraviolet absorption spectra, surface tension, fluorescence polarization, quantum yield, and the number of water molecules in the first coordination sphere of the Eu 3+ complex. 相似文献
9.
Eu 3+ ions are anchored on TiO 2 matrix by coupling with 2,2′-bipyridyl 4,4′-dicarboxylic acid. Five different luminescence centers are observed for TiO 2|2,2′-bipyridyl 4,4′-dicarboxylic acid|Eu 3+ electrodes due to electron transitions between d and f orbitals. Photo-luminescence of TiO 2|2,2′-bipyridyl 4,4′-dicarboxylic acid|Eu 3+ electrodes is increased by attaching 2-thenoyltrifluoroacetone to Eu 3+ ions. Immersion of TiO 2|2,2′-bipyridyl 4,4′-dicarboxylic acid|Eu 3+|2-thenoyltrifluoroacetone electrodes in propylsulfide is found to be further increased intensities of luminescence bands by a factor of three. 相似文献
10.
This work reports the synthesis and luminescent properties of complexes of europium(III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen), in the solid state. The new complexes were characterized by elemental analysis, infrared (IR) spectroscopy, scanning electronic microscopy (SEM) and thermal stability analysis. Both binuclear complex Eu 2(TPA)(TTA) 4Phen 2 and polynuclear complex Eu(TPA)(TTA)Phen present better thermal stability than the mononuclear complex Eu(TTA) 3Phen does. The formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra show narrow emission bands that arise from the 5D 0→ 7F J ( J=0-4) transition of the Eu 3+ ion. The spectral data of the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 present only one sharp peak in the region of the 5D 0→ 7F 0 transition indicating that only one Eu 3+ ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 fit a single-exponential decay law. The values of quantum efficiencies of the emitting 5D 0 level for the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 are 29% and 28%, respectively. 相似文献
11.
The complexes tris(4,4,4-Trifluoro-1-(1-naphthyl)-1,3-butanedionate) (2,2′-bipiridyl) Ln(III), Ln(tan) 3bipy, where Ln(III)=Eu 3+ and Gd 3+ have been synthesized, characterized and their photophysical properties (absorption, excitation and luminescence spectra and emission quantum yield) investigated down to 4.2 K. The Eu(tan) 3bipy complex has its molecular structure experimentally determined using X-ray crystallography and theoretically using the SMLC/AM1 method as well as their electronic singlet and triplet states were calculated, using the INDO/S-CI method with a point charge model to represent the Eu 3+ ion, where two values were adopted, +3.0 e and +3.5 e, to investigate the imperfect shielding of the 4f shells. The so calculated +3.5 e model electronic absorption spectrum and low lying triplet state energies agreed very well with the experimental ones. The emission quantum yield of the Eu 3+ complex is quite low at room temperature, namely 7%, probably due to the too low lying triplet state, 19,050 cm -1, and increases by a factor of three when the temperature is lowered to 4.2 K. This strong thermal effect indicates the presence of a channel deactivating the main emitting state, what can be due to a LMCT state possibly lying in the same spectral region, as usually found in Eu 3+ compounds. 相似文献
12.
The Mg 2SnO 4:Eu 3+ phosphor with reddish photoluminescence, green afterglow and photostimulated luminescence is obtained by the solid state method. The host related afterglow is greatly enhanced by doping of Eu 3+ and it can last nearly 6 h when the Eu 3+ concentration is 1 mol%. The photostimulated luminescence is found to be weakened by doping of Eu 3+. It was revealed that all the shallow traps and a part of the deep traps are involved in afterglow. The majority of deep traps are responsible for photostimulated luminescence. The impact of doping Eu 3+ on the afterglow and photostimulated luminescence is investigated and we propose a feasible interpretation. 相似文献
13.
The kinetics of luminescence and transformation of short-lived products of the photolysis of europium and lanthanum complexes
with thenoyltrifluoroacetone and 1,10-phenanthroline and their mixtures in polymethyl methacrylate films was studied by the
nanosecond laser photolysis method with recording both light emission and absorption. Fast (535 and 585 nm, 5
D
1 → 7
F
0, 7
F
3, decay time 0.7 μs) and slow (613 nm, 5
D
0 → 7
F
2, luminescence rise and decay times 0.7 μs and 0.5 ms, respectively) luminescence was studied. Induced absorption with a maximum
at 600 nm and decay time ∼3 ms was observed; this absorption was assigned to triplet states of the deprotonated form of thenoyltrifluoroacetone.
The dependences of luminescence intensity on the concentration of the components in a mixture of complexes were analyzed,
and synergistic effects of luminescence strengthening were estimated. The kinetics of a decrease in luminescence intensity
during photolysis was studied. Possible mechanisms of a decrease in the relative initial process rate and an increase in the
quasi-stationary value of relative luminescence intensity as the concentration of complexes in the polymer increased were
discussed. 相似文献
14.
A series of rare earth ternary compounds of Tb 1−xEu x(TTA) 3Dipy (HTTA=thenoyltrifluoroacetone, Dipy=2,2′-dipyridyl) have been synthesized, and the characteristics of the compounds have been performed by DTA-TG, IR, UV and fluorescence spectroscopy. Photoluminescence measurements indicated that the complexes of Eu(III) emit strong red luminescence under UV radiation. IR spectra suggest that complexes have been successfully synthesized, and TG curves indicate that the complexes are stable up to a temperature of about 220 °C. The Eu complex was blended with poly( N-vinylcarbazole) (PVK) and spin coated into films, and electroluminescence devices with the structure of Indium Tin Oxide (ITO)/PVK:Tb 1−xEu x(TTA) 3Dipy/BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)/aluminum quinoline (AlQ)/Al were fabricated, the luminescence of Eu 3+ complexes enhances after doping with Tb 3+. Therefore, it may be an effective method to improve the EL intensity of the lanthanide complex. 相似文献
15.
In order to study different characteristic luminescence of Eu 2+ and Sm 3+, delayed photoluminescence (DPL) and infrared stimulated luminescence (ISL) spectra of CaS doped with europium and samarium have been investigated. The influence of Eu and Sm concentration on luminescence of Eu 2+ in photoluminescence (PL) and ISL was respectively studied. It was found that, at low doping levels, PL emission intensity of Eu 2+ increased linearly with increment of Eu, while decreased linearly with increment of Sm. However, further increment of Eu and Sm in CaS:Eu,Sm could not increase either the luminescent centres of Eu 2+ or electron trapping sites of Sm 3+. Different local environment of Eu 2+ and Sm 3+ in the lattice position is thought to be the cause of all observed luminescence phenomena. Finally, the maximum emission in ISL was obtained at 1000 ppm europium and 750 ppm samarium. 相似文献
16.
We have synthesized heterometallic complexes based on a copolymer of acrylic acid with butyl methacrylate (BMAC) with a composition [Eu x Bi (1 ? x)-BMAC]. These complexes have several emission bands in the visible range. At room temperature, in complexes with a content of Eu(III) of 30–40%, intense white luminescence appears. 相似文献
17.
The luminescence properties of Ba 3Tb 0.9Eu 0.1(PO 4) 3 and Ba 3Gd 0.9Eu 0.1(PO 4) 3 phosphors were studied for excitation over the 120-300 nm wavelength range. It is found that Tb 3+, which exhibits a strong vacuum-ultraviolet (VUV) absorption band, provides sensitisation of Eu 3+ emission in this host. This effect can be used to develop phosphors with enhanced conversion efficiency of the VUV radiation into visible light. 相似文献
18.
We studied sensitization of Eu(III) and Tb(III) ions by molecules of 1,10-phenanthroline and 2,2-bipyridil in D 2O and d 6-ethanol and the influence of Nd(III), Pr(III), Sm(III), Gd(III), and Ho(III) ions on the luminescence intensity I lum and lifetime τ lum of Eu(III) and Tb(III) in solutions. The stability constants of complexes of Eu(III) and Gd(III) with 2,2′-bipyridil are measured by spectrophotometric and luminescence methods. It is shown that luminescence of Eu(III) is quenched by Gd(III) ions at the ion concentration equal to 10 ?2–10 ?1 M, which is caused by competing between these ions for a sensitizer. At the concentration of Ln(III) ions equal to 10 ?6?10 ?3 M, the sensitized luminescence of Eu(III) and Tb(III) was quenched and τ lum decreased in the presence of Nd(III) ions, whereas in the presence of Gd(III) the luminescence intensity increased. It is proved that a bridge that connects the two ions upon energy transfer is formed by hydroxyl groups. The intensity of luminescence of Eu(III) and Tb(III) in aqueous solutions and its lifetime decreased in the presence of hydroxyl groups, while upon addition of Gd(III) to these solutions these quantities were restored. We also found that the addition of Gd(III) to deoxygenated ethanol solutions of 2,2′-bipyridil and Eu(III) slows down photochemical and thermal reactions between bipyridil and Eu(III), resulting in the increase in the luminescence intensity of Eu(III). 相似文献
19.
Yttrium aluminum garnet nanoparticles both undoped and doped with lanthanide ions (Ce 3+, Eu 3+, Dy 3+ and Tb 3+) having average size around 30 (±3 nm) nm were prepared by glycine nitrate combustion method followed by annealing at a relatively low temperature of 800 °C. Increase in the annealing temperature has been found to improve the luminescence intensity and for 1200 °C heated samples there exists strong energy transfer from Tb 3+ to Ce 3+ ions in YAG:Ce(2%),Tb(2%) nanoparticles as revealed by luminescence studies. Co-doping the YAG:Ce nanoparticles with Eu 3+ results in significant decrease in the emission intensity of both Ce 3+ and Eu 3+ ions and this has been attributed to the oxidation of Ce 3+ to Ce 4+ and reduction of Eu 3+ to Eu 2+ ions. Dy 3+ co-doping did not have any effect on the Ce 3+ emission as there is no energy transfer between Dy 3+ and Ce 3+ ions. 相似文献
20.
Nanosized luminescent (Y,Bi)VO 4:Eu 3+ and Y(V,P)O 4:Eu 3+ were synthesized at low temperatures either by a coprecipitation method or by a hydrothermal method from aqueous solutions. The effect of Bi 3+ ion or P 5+ ion content in the lattice, annealing temperature effects on the crystal structure and the particle size, and the luminescence property of (Y,Bi)VO 4:Eu 3+ and Y(V,P)O 4:Eu 3+ nanoparticles were examined with a field-enhanced scanning electron microscopy, XRD, and a spectrofluorometer. The pristine YVO 4:Eu 3+, (Y,Bi)VO 4:Eu 3+, or Y(V,P)O 4:Eu 3+ nanoparticles are 35-50 nm in size. The luminescence spectrum of the Eu 3+ ion was used to probe its position in the crystal lattice. The dopant ions enter the same lattice sites in the nanocrystalline as in the corresponding bulk material, resulting similar spectral features between them. Photoluminescence intensity is weak for the pristine nanoparticles. Annealing the nanoparticles at temperatures up to 1000 °C results in the increased luminescence intensity (>80% of micrometer-sized phosphors) with the minimal particle growth and the improved particle crystallinity. 相似文献
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