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1.
We studied the persistent spectral hole-burning (PSHB) of the Eu3+-doped Al2O3-SiO2 glasses, prepared by a sol–gel process, exposed to femtosecond laser pulses. The spectral holes were burned in the excitation spectra of the 7F05D0 transition of Eu3+ ion. The depth and width of the burned holes were 15% and 2.5 cm–1 fwhm at 7 K, respectively. The burned hole is stable up to room temperature. Fluorescence line narrowing spectra showed that Eu3+ ions were located in two different sites.  相似文献   

2.
Fluorescence and spectral hole burning properties of Eu3+ ions were studied in nanocrystals-precipitated SnO2-SiO2 glasses. The glasses were prepared to contain various amount of Eu2O3 using the sol-gel method, in which SnO2 nanocrystals were precipitated by heating in air. In the glasses containing Eu2O3 less than 1%, the Eu3+ ions were preferentially doped in the SnO2 nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons and holes excited in SnO2 crystals. The SnO2 nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence intensities of the Eu3+ ions. With the increasing Eu2O3 concentration, the amount of SnO2 nanocrystals decreased and the Sn4+ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities and the hole depth to decrease.  相似文献   

3.
Chen HQ  Fu J  Wang L  Ling B  Qian BB  Chen JG  Zhou CL 《Talanta》2010,83(1):139-144
With the biomolecule glutathione (GSH) as a capping ligand, Eu3+-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process. An efficient fluorescence energy transfer system with CdS nanoparticles as energy donor and Eu3+ ions as energy accepter was developed. As a result of specific interaction, the fluorescence intensity of Eu3+-doped CdS nanoparticles is obviously reduced in the presence of Hg2+. Moreover, the long fluorescent lifetime and large Stoke's shift of europium complex permit sensitive fluorescence detection. Under the optimal conditions, the fluorescence intensity of Eu3+ at 614 nm decreased linearly with the concentration of Hg2+ ranging from 10 nmol L−1 to 1500 nmol L−1, the limit of detection for Hg2+ was 0.25 nmol L−1. In addition to high stability and reproducibility, the composite nanoparticles show a unique selectivity towards Hg2+ ion with respect to common coexisting cations. Moreover, the developed method was applied to the detection of trace Hg2+ in aqueous solutions. The probable mechanism of reaction between Eu3+-doped CdS composite nanoparticles and Hg2+ was also discussed.  相似文献   

4.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D07FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2.  相似文献   

5.
Fine Eu3+-doped lutetium oxide (Lu2O3:Eu3+) nanophosphor were synthesized using a low-temperature solution-combustion method in a methyl-alcohol solution. The characteristics of the nanophosphors synthesized at various sintering temperatures with different Eu3+ concentrations were analyzed to determine the optimum synthesis conditions. Thermogravimetry/differential thermal analysis showed that Lu2O3:Eu3+ crystallizes completely when the dry powder is sintered at 500 °C. The Lu2O3:Eu3+ crystals had a cubic structure and monoclinic phase. The peak position of the luminescence spectrum did not differ with the concentration of Eu or the sintering temperature or atmosphere, whereas the luminescence intensity was strongly dependent on the concentration and sintering conditions.  相似文献   

6.
Covalent organic frameworks (COFs) have been widely applied in gas capture and separation, but the fluorescent property of COFs with large π-conjugated system tends to be underexplored. Here we report the fluorescent properties of several COFs including TaTa, DhaTab, TRITER-1 and TzDa and the effect of metal ions of Na+, Mg2+, K+, Ca2+, Cu2+, Zn2+, Pb2+, Ag+, Cd2+ and Fe3+ on the fluorescence of these COFs. The results show that only Fe3+ significantly quenched the fluorescence of the studied COFs. The possibility of the four COFs for selective sensing of Fe3+ was demonstrated. The possible mechanism of the effect of Fe3+ on the fluorescence of the COFs was based on the absorption competition quenching.  相似文献   

7.
Emission properties of Eu2+-doped M3MgSi2O8 (M: Ba, Sr, Ca) are discussed in terms of the crystal structure. When Ba2+ ions account for over one third of M2+ ions, M3MgSi2O8 crystallizes in glaserite-type trigonal structure, while Ba-free compounds crystallize in merwinite-type monoclinic structure. Under UV excitation, the Eu2+-doped glaserite-type compounds exhibit an intense blue emission assigned to 5d-4f electron transition at about 435 nm, regardless of the molar ratio of Ba2+, Sr2+ and Ca2+ ions. By contrast, the Eu2+-doped merwinite-type compounds show an emission color sensitive to the ratio. A detailed analysis of the emission spectra reveals that the emission chromaticity for the Eu2+-doped M3MgSi2O8 is composed of two emission peaks reflecting two different sites accommodating M2+ ion.  相似文献   

8.
Highly luminescent euxenite phased YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ red phosphors have been prepared through a facile sol–gel combustion process and investigated for the first time. The introduction of Li+ ions into YNbTiO6:Eu3+ is able to result in significant changes of the crystallinity and particle size, and bring a clear red-shift of absorption edge. A dominant red emission peak at 611 nm due to the 5D0  7F2 transition of Eu3+ was observed from photoluminescence spectra of the YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ phosphors. In particular, the emission intensity of the optimal Li+-doped YNbTiO6:Eu3+ was examined to be close to 400% of commercial Y2O3:Eu3+ phosphor. The mechanism of the enhanced emission by Li+ doping was discussed.  相似文献   

9.
Eu3+-doped boehmite nanofiber materials with different Eu3+ concentrations were synthesized without any surfactant, and followed by a series of characterizations. It was found that the boehmite nanofibers became coarser with the increase of Eu3+ concentration, which resulted in a gradual decrease of their specific surface areas. Moreover, the thermal stability of the boehmite nanofibers was studied by thermogravimetry–differential scanning calorimetry. All materials showed the phase transition from γ-Al2O3 to other forms. Yet the transition temperature was increased with the increase of Eu3+ concentration. The Eu3+-doped boehmite nanofibers with the maximum Eu3+ concentrations showed the best thermal stability. Photoluminescence spectra showed that the 2 mol% of doping concentration of Eu3+ ions in Eu3+:Al2O3 nanofiber was optimum.  相似文献   

10.
A new bis-Schiff base ligand, N,N-bis-(4-N-aminothiourea-2-amylidene)-4,4-diaminodiphenyl ether (ARADE), was synthesized. Its complex with Eu3+ in DMF emits the intrinsic fluorescence of Eu3+. The fluorescence intensity of the Eu3+-ARADE system was enhanced about 60-fold by the addition of hexamethylene tetramine (HMTM) and potash alum. This is a new fluorescence enhancement phenomenon. The excitation and emission wavelengths are 375nm and 615nm, respectively. Under optimal conditions, the fluorescence intensities vary linearly with the concentration of Eu3+ in the range of 7.8×10–9–1.75×10–5mol·L–1 with a detection limit of 5.2×10–9mol·L–1, or with the concentration of Al3+ in the range of 3.1×10–7–9.7×10–5mol·L–1 with a detection limit of 2.7×10–7mol·L–1. The interferences of some rare earth metals and other inorganic ions were described. This method was applied to the determination of Eu3+ in high purity yttrium oxide and the analysis of Al3+ in alloy steel standard samples. The mechanism of fluorescence enhancement was also studied.  相似文献   

11.
The crystal-field (CF) spectra of Eu3+ in various inorganic crystalline phases are summarized based on previous investigations. A majority of experimental results can be well interpreted using a standard CF model. However, there are cases in which the spectroscopic properties and fluorescence dynamics of Eu3+ cannot be interpreted within the framework of the standard model. A particularly interesting system is Eu3+ doped into microcrystals of a charge-unbalanced host such as BaFCl. For Eu3+:BaFCl, one Eu3+ site (Site I) exhibits normal CF splitting and its energy levels and fluorescence intensity are similar to most other normal systems ever reported. A standard CF fitting has been performed for Site I. However, Eu3+ at a distorted site (Site II) is of anomalous fluorescence dynamics and CF splitting which are significantly different from those of Site I. In the metastable state of 5D0, Eu3+ ions at Site II also exhibit unusual temperature-dependent lifetime.  相似文献   

12.
Eu2+-doped inorganic-organic hybrid materials, which are potentially suitable for a tunable laser in the near ultra violet and blue region, were prepared through the photoreduction of Eu3+ ions in the materials under the irradiation of the fourth harmonic wave light (266 nm) of the Nd:YAG laser. The hybrid materials doped with Eu3+ ions were prepared from Si(OCH3)4, CH3Si(OCH3)3, EuCl3 and chloropropyltrimethoxysilane (CPTM). After the prehydrolized silica sol was added to the Eu3+-containing solution, Eu3+-doped transparent inorganic-organic hybrid material was obtained by drying at 50°C. The emission peak around 450–475 nm due to the charge transfer transition (5d-4f) of Eu2+ ions increased with the laser irradiation time. Eu3+ ions were effectively photoreduced to Eu2+ ions in pore-free materials prepared at high CPTM to Eu3+ ratios. Eu2+ ions were generated by the photodecomposition of the bond between Eu3+ and Cl (Cl or Cl(CH2)3 in CPTM).  相似文献   

13.
Eu3+ ion-doped LaPO4 nanowires or nanorods have been successfully synthesized by a simple hydrothermal method. The influence of varying the hydrothermal and subsequent sintering conditions on the morphology and structure of the LaPO4 host has been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). For comparison, the Eu3+ ions were also doped into monoclinic monazite LaPO4 nanoparticles and perovskite LaAlO3 nanoparticles. The relative intensities of the emission lines of the LaPO4:Eu3+ nanosystems were essentially independent of their shape. The optimal doping concentrations in the monoclinic LaPO4 and perovskite LaAlO3 nanosystems were determined to be about 5.0 and 3.5 mol%, respectively. Under appropriate UV-radiation, the red light emitted from LaAlO3:Eu3+ (3.5 mol%) was brighter than that from LaPO4:Eu3+ (5.0 mol%) nanomaterial, resulting from differences in their spin-orbit couplings and covalence, which indicates that the nanoscale LaAlO3 is a promising host material for rare earth ions. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. Supported by the National Natural Science Foundation of China (Grant Nos. 20873039 & 90606001), Hunan Provincial Natural Science Foundation (No. 07jj4002), and the Students Innovation Training Fund of Hunan University  相似文献   

14.
Uniform Eu3+-doped SiO2 nanorods were synthesized through a simple sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant template and tetraethylorthosilicate as silicon source. X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrum, scanning electron microscope (SEM), transmission electron microscopy, and photoluminescence spectra were employed to characterize the products in detail. The nanorods have good uniformity and their diameters and lengths are in the range of 200–300 and 500–700 nm through the SEM images, respectively. The formation of the nanorods was studied by taking SEM images after different aging time. The experimental results indicate that CTAB plays a crucial role in the formation of the silica nanorods. The luminescence of Eu3+-doped SiO2 nanorods is dominated by red-emission around 612 nm due to intra-atomic 4f → 4f (5D0 → 7F2) transition of Eu3+ ions. Furthermore, the effect of doping concentrations of Eu3+ ions on the luminescence was investigated.  相似文献   

15.
In3+-doped BiVO4 nanoparticles with enhanced visible light activity have been successfully synthesized by a hydrothermal method. The synthesized materials were characterized by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, BET surface areas analysis, and ultraviolet–visible diffuse reflectance spectra. In comparison with pure BiVO4, the In3+-doped BiVO4 displayed greater photocatalytic activity in the degradation of methyl blue under visible light illumination. All samples possessed a single monoclinic structure. The introduction of In ions resulted in structural distortion and the decreased band gap energy, producing more electrons and holes for photocatalytic reaction. In the meantime, the doping In ions entails a red shift in the absorption edge and an increase in the intensity of light absorption. The best photocatalytic performance was obtained with the BiVO4 sample containing 5.0 mol% In ions.  相似文献   

16.
A novel 1,8-naphthalimide dye with simple structure has been produced by a facile synthetic method for colorimetric and fluorescent sensing of H+ and Cu2+. In CH3CN/H2O (1/1, v/v), the dye could monitor H+ using dual channels (ratiometric absorbance and fluorescence intensity change) from pH 6.2 to 12.0. Meanwhile, in the pH range of 1.9–5.2, the dye could also be used to detect Cu2+ using triple channels [ultraviolet–visible (UV–Vis) absorption, fluorescence intensity reduction, as well as fluorescence blueshift]. The detection limits for Cu2+ evaluated by colorimetric and fluorescent titration were 6.10 × 10?7 and 2.62 × 10?7 M, respectively. The dye exhibited specific selectivity and sensitivity for H+ and Cu2+ over various coexisting metal ions. Moreover, the sensing mechanism of the dye for H+ and Cu2+ was carefully examined.  相似文献   

17.
Summary This paper reports the radiochemical study of the ion-exchange of Cs+, Na+, Sr2+ and Eu3+ ions with H+ by chromium hexacyanoferrate(II) which was prepared in a granular form using a gel method. The slow steps which determine the rate of exchange of these ions are directly proportional to the particle diameter and this is confirmed from the linearity test of Bt vs. t plots at different particle diameters. Boyed’s equation and Reichenberg’s tables were used for evaluating all the kinetic parameters. The results reveal that the effective particle radii are unchanged for both chromium hexacyanoferrate(II) dried at 60 and 120 °C. The obtained data were analyzed using McKay plots and Arrhenius equation and the kinetic and thermodynamic parameters, e.g., effective diffusion coefficient, activation energies and entropies of activation have been evaluated. The mobility of these ions inside the particles of chromium hexacyanoferrate(II) decrease in the order of Eu3+>Sr2+>Na+⊃Cs+.  相似文献   

18.
A rhodamine-conjugated coumarin (L) was used in designing a selective fluorescence chemosensor for the determination of trace amounts of Cr3+ ions in acetonitrile–water (MeCN/H2O (90:10, %v/v) solutions. The intensity of the fluoresce emission of the chemosensor is intensified upon addition of Cr3+ ions in MeCN/H2O (90:10, %v/v) solutions, due to the formation of a selective 1:1 complex between L and Cr3+ ions. The fluorescence enhancement versus Cr3+ concentration has been found to be linear from 1.0?×?10?7 to 1.8?×?10?5 M and a detection limit of 7.5?×?10?8 M. The proposed fluorescent probe proved to be highly selective towards Cr3+ ions as compared to other common metal ions and could be successfully applied to the determination of Cr3+ concentrations in some water and wastewater samples.  相似文献   

19.
4-[(2-Hydroxy-naphthalen-1-ylmethylene)-amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (HDDP) was synthesized by the reaction of 4-amino-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with 2-hydroxy-l-naphthaldehyde. The structure was confirmed by the IR, 1H-NMR, 13C-NMR, and EI-MS spectra and elemental analysis. Physicochemical parameters of the HDDP such as extinction coefficient, oscillator strength, transition dipole moment, Stokes shift, and fluorescence quantum yield in different solvents were studied on the basis of polarities. The interactions of various metal ions with HDDP were also studied using steady state fluorescence measurements. The emission profile reveals that it acts as off–on type fluorescent chemosensor for selective and sensitive detection of Al3+ ions. Complexation stoichiometry and mechanism of enhancement were determined from a Benesi–Hildebrand plot.  相似文献   

20.
Eu2+/Dy3+-codoped BaAl2O4 phosphors were prepared by conventional solid-state reaction with boric acid flux. The effects of boric acid on structural and luminescent properties of BaAl2O4:(Eu2+, Dy3+) were investigated. The crystallinity of BaAl2O4 improved with increasing amount of H3BO3. Incorporation of Eu2+ and Dy3+ ions into effective lattice sites was promoted by H3BO3 addition. As a result, Eu2+ emission in BaAl2O4 was greatly enhanced by H3BO3, and the duration of persistent luminescence increased with the amount of H3BO3. However, the decay lifetime of persistent luminescence was not strongly influenced by the amount of H3BO3.  相似文献   

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