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A Novel Rare Earth Ion Fluorescent Probe towards the Trace Detection of 2,4,6-Trinitrotoluene Based on Fluorescence Resonance Energy Transfer
摘要： This paper reports a resonance energy transfer-fluorescence quenching of the core-shell structure of CaMoO4:Tb3+@SiO2 modified by amino group on the surface for the ultrasensitive and ultratrace detection of 2,4,6-trinitrotoluene (TNT) in solution environments. Organic amine was covalently modified onto the surface of silica shell to form a hybrid monolayer of amino group. The particle can specifically bind TNT species by the charge-transfer complexing or acid-base pairing interactions between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT-amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from CaMoO4:Tb3+ fluorescence donor to the irradiative TNT-amine acceptor through intermolecular polar-polar interactions at spatial proximity. The nanoparticle can sensitively detect down to 1 nM TNT with the use of only 10 μL of solution (2 pg TNT). The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes.
关键词： Fluorescence quenching,FRET,Ultratrace detection,2,4,6-Trinitrotoluene,Rare earth ion
更新于2025-09-11 14:15:04
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Correlation between composition, microstructure, and emission properties in Nd-doped Si-rich Si oxynitride films: investigation into the nature of the sensitizer
摘要： Rare earth (RE) ions doped in Si-based materials, compatible with Si technology, are promising compounds with regards to optical communication and energy conversion. In this article, we show the emission properties of Nd-doped Si-rich Si oxynitride (Nd-SRSON) ?lms, and their dependence on the dangling bond density and the nature of the sensitizer. These ?lms were prepared by reactive magnetron sputtering and post-annealing. The ?lm composition, microstructure, and emission properties were investigated as a function of deposition parameters and annealing temperatures. Both Fourier transform infrared (FTIR) and ellipsometry spectroscopy measurements have con?rmed that the sample composition (Si/N ratio) can be carefully tuned by varying the ratio of reactive nitrogen to argon in the sputtering plasma. Moreover, FTIR and x-ray photoelectron spectroscopy measurements demonstrate the existence of both nitrogen and oxygen dangling bonds (N? and O?) in as-deposited samples. These dangling bonds were passivated during annealing. Under non-resonant excitation at 488 nm, the ?lms exhibit a signi?cant photoluminescence (PL) signal from Nd3+ ions demonstrating the occurrence of an effective sensitization of Nd3+ ions in the host matrix. Both PL excitation and ellipsometry results (the energy band gap from new amorphous model) exclude the sensitization by an exciton with energy over the band gap, whereas the presence of Si agglomerates, at the atomic scale, have been identi?ed as effective sensitizers towards Nd3+ ions. This work not only provides knowledge to optimize Si-based materials for favorable emission properties, but also, presents a universal methodology to investigate the nature of sensitizers for RE emitters. This allows one to ?nd correlations between composition, microstructure, and emission properties.
关键词： photoluminescence,rare earth,neodymium,non-resonant excitation,thin ?lm,Si-rich Si oxynitride
更新于2025-09-10 09:29:36
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Investigation of luminescence mechanism of Nd3+-doped calcium aluminate glasses: Effect of glass-formers
摘要： The relationship between the luminescence properties and the glass structure of Nd3+-doped CaO-Al2O3-(B2O3, SiO2, or Ga2O3) glasses are investigated. The luminescence properties of CaO-Al2O3-B2O3 system are twice as much as that of the CaO-Al2O3-(SiO2 or Ga2O3) system. The glass structure and the coordination environment of the Nd3+ ions were investigated using nuclear magnetic resonance, Raman and electron paramagnetic resonance spectroscopy. All Al, Ga, and Si atoms are four coordinated. The B atoms have three- and four-coordinated boron units, however, most of them are three coordinated. The hyper?ne sublevel correlation spectra reveal that the Al and B nuclei are in the coordination sphere of Nd3+ ions for aluminoborate glasses; however, only 27Al signals could be observed for aluminosilicate and aluminogallate glasses. Owing to the increased number of AlO4-BO3 connections and 11B nuclei around the Nd3+ ions, B has a signi?cant e?ect on the luminescence properties of the Nd3+ ions. The increase in GaO4 or SiO4 does not change the three dimensional-tetrahedral network, and the coordination environment of Nd3+ ions varies slightly. Thus, the e?ect of Ga2O3 and SiO2 on the luminescence properties of the Nd3+ ions is not as great as that of B2O3.
关键词： Glass structure,Local environments of rare-earth ions,EPR,Luminescence properties,NMR
更新于2025-09-10 09:29:36
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Effect of capacitance on ZnO-Bi2O3-Yb2O3 based varistor for nanosecond transients; 电容对毫微秒瞬变用 ZnO-Bi2O3-Yb2O3 基压敏电阻的影响;
摘要： The microstructure and electrical properties of ZnO-Bi2O3-Yb2O3 based varistor ceramics were investigated with various temperature effects from 900 °C to 1050 °C. From the results, it was observed that the increase of sintering temperature offers a reduced capacitive effect from 0.460 nF to 0.321 nF. Furthermore, the grain sizes of varistors were varied from 6.8 μm to 9.8 μm. The consequence of such smaller grain sizes provided a better voltage gradient of about 895 V/mm for the disc sintered at 900 °C and fallen drastically to 410 V/mm for the sample sintered at 1050 °C. In addition, there was an increase of non-linearity index to a maximum value of 36.0 and reduced leakage current of 0.026 mA/cm2. However, the density of the varistor decreased with an increase of temperature from 5.41 g/cm3 to 5.24 g/cm3. With this base, the influence of varistor capacitance and high voltage gradient were scrutinized and it led an improved transition speed of the varistor assembly from non-conduction to conduction mode during intruding nanosecond transients.
关键词： nanosecond transient,rare earth oxide,metal oxide varistor,transition delay,capacitance,ytterbium oxide
更新于2025-09-10 09:29:36
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Alkaline-Earth Fluorohalide Nanocrystals for Upconversion Thermometry
摘要： The temperature-dependent luminescence response of SrFCl:Yb,Er and SrFBr:Yb,Er upconverting nanocrystals was investigated with an eye towards the expansion of the library of host materials for optical thermometry. Steady-state and luminescence decays of the 2H11/2 and 4S3/2 thermally coupled levels of the Er3+ activator were probed in the 100?450 K temperature range. Fluorescence intensity ratios and thermometric sensitivities were extracted in two temperature regimes. In the low-temperature regime, SrFCl:Yb,Er and SrFBr:Yb,Er displayed maximum sensitivities of 3.2 × 10?2 K?1 (125 K) and 2.1 × 10?2 K?1 (175 K), respectively. In the high-temperature regime, sensitivities were comparable to those observed in upconverting nanocrystals such as NaYF4:Yb,Er at room temperature, with values of 9.4 × 10?3 K?1 (325 K) for SrFCl:Yb,Er and 1.1 × 10?2 K?1 (300 K) for SrFBr:Yb,Er. The observed temperature-dependent responses resulted from long- and short-lived Er3+ emitters present in both fluorohalide hosts. For each type of emitter, radiative constants and activation energies for thermal quenching of the emission from the 4S3/2 level were estimated using a single-barrier quenching model. The local atomic environments of the long- and short-lived Er3+ emitters differed to a greater extent in SrFCl:Yb,Er than in SrFBr:Yb,Er.
关键词： SrFBr,Nanocrystals,Thermometry,SrFCl,Upconversion,Rare-earth
更新于2025-09-10 09:29:36
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Electrospinning Construction of Flexible Composite Nanoribbons with Color-Tunable Fluorescence
摘要： Herein, we describe the innovative one-dimensional nanomaterials, electrospun composite nanoribbons (width 10.119 ± 0.186 μm) containing complexes of Eu(TTA)3(TPPO)2 and Tb(BA)3phen in a matrix of polymethylmethacrylate (PMMA). Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and fluorescence spectroscopy were used to characterize the final products. The novel luminescent composite nanoribbons exhibit green, orange and red fluorescence emission peaks at 490, 545, 592, and 615 nm, which are ascribed to the 5D4 → 7F6 (490 nm) and 5D4 → 7F5 (545 nm) energy transitions of Tb3+ ions, and the 5D0 → 7F1 (592 nm), 5D0 → 7F2 (615 nm) transitions of Eu3+ ions, respectively. It is observed that the doping percentage and the chosen excitation wavelength could be used to tune the emission color of the samples. The color-tunable luminescent composite nanoribbons have potential applications in the fields of display panels, lasers and bioimaging.
关键词： fluorescence,electrospinning,composite nanoribbons,rare earth complexes,tunable color
更新于2025-09-10 09:29:36
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Encyclopedia of Spectroscopy and Spectrometry || Optical Spectroscopy of Rare-Earth Ions in the Solid State
摘要： The birth of optical spectroscopy as science can be considered from the time when in 1672 Isaac Newton published his famous paper describing the results of experiments where, using a glass prism, he decomposed a beam of sunlight into its optical spectral components ranging from blue to red. Since that time, scientists and engineers studied a broad range of phenomena associated with the interaction of light with matter, using the fact that light actually contains different spectral components. Within a field of optical spectroscopy, it is hard to underestimate the importance of optical spectroscopy of different optical centers in solid-state materials because of numerous scientific and industrial applications of such optical systems. These applications range from studying fundamental properties of impurity centers in solids, solid-state material properties, up-conversion devices, scintillators, and Faraday rotators to a creation of solid-state lasers.
关键词： rare-earth ions,Fu¨chtbauer–Ladenburg theory,optical spectroscopy,Judd–Ofelt theory,McCumber theory,electron–phonon coupling,Franck–Condon principle,solid state
更新于2025-09-10 09:29:36
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Tracing of dye molecules in living plants through NaGdF4:Yb3+,Er3+ fluorescent nanoprobes
摘要： In this paper, we demonstrated trace of dye molecules in living plants. The NaGdF4:Yb3+,Er3+ nanoparticles probe was used to detect the rhodamine B(RhB) in bean sprout. It is found that the fluorescencedye can be efficiently imbibed during the growing process and the absorbance presented a position dependence effect, which was supported by the upconversion spectra and the fluorescent image characterization. In addition, the concentration of the residual RhB in bean sprout can be efficiently traced by the synthesized probe based on the fluorescent resonant energy transfer. Finally, the relation between the excitation power, concentration and the ratio of yellow to green emission are discussed in detail. These results can be helpful in understanding the RhB dye molecules absorbance process in vegetable growth and provide an efficient way to trace the residual dyes in vivo plant.
关键词： Upconversion nanoprobes,Rare-earth-doped materials,fluorescence,Biological sensing and sensors,luminescence
更新于2025-09-10 09:29:36
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EPR study of luminescence mechanism of Nd3+-doped borate aluminum glass
摘要： The luminescence mechanisms of Nd3+: B2O3-Al2O3-CaO glasses with different amounts of B2O3 were investigated based on their electron paramagnetic resonance spectra and luminescence properties. The results of the echo-detection field sweep exhibited two different maxima indicating that Nd3+ ions occupy two different sites. 27Al and 11B signals in two-dimensional hyper?ne sublevel correlation spectra were observed in the (+, +) quadrant, indicating that both 27Al and 11B are located in the second or higher order Nd3+ coordination shell. In addition, the fraction of the 11B nucleus present in the Nd3+ coordination sphere increased with an increase in the amount of B2O3. The continuous changes in the hypersensitive transition intensity and luminescence properties are strong indicators for the change in the Nd3+ coordination environment.
关键词： 2D-HYSCORE,EPR,rare-earth ion local environment,borate aluminum glass
更新于2025-09-10 09:29:36
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Solid-State Preparation, Structural Characterization, Physical Properties and Theoretical Studies of a Series of Novel Rare-earth Metal-Chalcogenides with Unprecedented Closed Cavities
摘要： Multinary rare-earth metal-chalcogenides have aroused great concern owing to their special structure characteristics and diverse physical functions. In this work, five novel rare-earth chalcogenides adopt the formula Cs2[RE8InS14] (where RE = Ho–Lu), has been obtained by the elementals mixture in CsCl flux at 1273 K. They are isotype and belong to the orthorhombic Cmca (no. 64) [a = 15.711(7)–15.385(2) ?, b = 22.232(2)–21.786(2) ?, c = 15.483(5)–15.244(2) ?, V = 5408.4(4)–5130.1(7) ?3 and Z = 8], exhibiting a dense 3D [RE8InS14] framework consisting of RES6 octahedron and discrete InS4 tetrahedron. The large closed-cavities Cs4@S26 are far apart embedded within the network along bc-plane, which is discovered for the first time. The band gaps from 2.45 to 2.72 eV for Cs2[RE8InS14] were deduced from the UV?Vis–NIR spectroscopy based on the Kubelka-Munk function. Magnetic test indicates that the Cs2[RE8InS14] (RE = Ho–Yb) compounds possess para-magnetism above 50K. In addition, the solid-state preparation, structural characterization, theoretical studies together with a structure–G/H ratio relationship (G = atomic number of guest metals; H = atomic number of host metals) are also presented.
关键词： crystal structure,solid-state reaction,magnetic properties,large closed cavities,rare-earth metal-chalcogenides
更新于2025-09-10 09:29:36