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Silver nanoflowers-enhanced Tb(III)/La(III) co-luminescence for the sensitive detection of dopamine
摘要： A sensitive fluorescent analytical method for the detection of dopamine (DA) was developed based on surface-enhanced Tb(III)/La(III) co-luminescence using silver nanoflowers (AgNFs). Anisotropic AgNFs show strong surface-enhanced fluorescence effect owing to the abundant sharp tips. Tb(III)/La(III)-DA complexes mainly bind to the sharp tips of AgNFs and thus shorten the distance between the complexes. The shortened distance gives rise to obvious surface-enhanced Tb(III)/La(III) co-luminescence effect. In this work, AgNFs offer many superior properties, such as enhanced intrinsic green fluorescence of Tb(III) (λex/λem = 310/546 nm), increased fluorescence lifetime, and improved energy transfer efficiency. Under the optimum conditions, the fluorescence intensity is linearly correlated with the concentration of DA in the range of 0.80–10 nM (R2 = 0.9970), and the detection limit is 0.34 nM (S/N = 3). The fluorescent nanoprobe was successfully applied to the determination of DA in human serum samples with recoveries ranging from 99.1 to 102.6%.
关键词： Co-luminescence,Anisotropic nanoparticles,Surface-enhanced fluorescence,Rare earth elements,Dopamine,Silver nanoflowers
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Development of mercury-free ultraviolet light emitting devices
摘要： We developed rare-earth doped phosphors for mercury-free narrowband ultraviolet light sources. The narrowband emission is a typical feature of the intra-orbital electron transition in the rare-earth Gd3+ ion. Al1-xGdxN epitaxial films were grown by using an ultra-pure reactive sputtering technique performed under molecular-beam epitaxial quality. A narrowband luminescence line from Gd3+ ions has been observed at 318 nm. We fabricated field-emission devices using Al1-xGdxN thin films and investigated detailed device characteristics. Furthermore, recently, we have successfully developed bright fluorescent lamps with an ultraviolet phosphor containing Gd3+ ions.
关键词： mercury free,ultraviolet,light source,rare-earth
更新于2025-09-23 15:21:21
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Luminescent nanomaterials for droplet tracking in a microfluidic trapping array
摘要： The use of high-throughput multiplexed screening platforms has attracted significant interest in the field of on-site disease detection and diagnostics for their capability to simultaneously interrogate single-cell responses across different populations. However, many of the current approaches are limited by the spectral overlap between tracking materials (e.g., organic dyes) and commonly used fluorophores/biochemical stains, thus restraining their applications in multiplexed studies. This work demonstrates that the downconversion emission spectra offered by rare earth (RE)-doped β-hexagonal NaYF4 nanoparticles (NPs) can be exploited to address this spectral overlap issue. Compared to organic dyes and other tracking materials where the excitation and emission is separated by tens of nanometers, RE elements have a large gap between excitation and emission which results in their spectral independence from the organic dyes. As a proof of concept, two differently doped NaYF4 NPs (europium: Eu3+, and terbium: Tb3+) were employed on a fluorescent microscopy-based droplet microfluidic trapping array to test their feasibility as spectrally independent droplet trackers. The luminescence tracking properties of Eu3+-doped (red emission) and Tb3+-doped (green emission) NPs were successfully characterized by co-encapsulating with genetically modified cancer cell lines expressing green or red fluorescent proteins (GFP and RFP) in addition to a mixed population of live and dead cells stained with ethidium homodimer. Detailed quantification of the luminescent and fluorescent signals was performed to confirm no overlap between each of the NPs and between NPs and cells. Thus, the spectral independence of Eu3+-doped and Tb3+-doped NPs with each other and with common fluorophores highlights the potential application of this novel technique in multiplexed systems, where many such luminescent NPs (other doped and co-doped NPs) can be used to simultaneously track different input conditions on the same platform.
关键词： Rare earth elements,Single-cell analysis,Nanoparticles,Microfluidics,high-throughput screening
更新于2025-09-23 15:21:21
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Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis
摘要： In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are con?rmed by X-ray di?raction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 °C exhibited a linear dose response in the range of 0.1–10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The e?ects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710 nm assigned to the 5D0→7FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition 5D0→7F2 was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition 5D0→7F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.
关键词： Thermoluminescence,Zinc borates,XRD,Cathodoluminescence,Rare earth
更新于2025-09-23 15:21:21
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Soluble and insoluble polymer-inorganic systems based on poly(methyl methacrylate), modified with ZrO2-LnO1.5 (Ln = Eu, Tb) nanoparticles: Comparison of their photoluminescence
摘要： The study of the lanthanide ion luminescence as a function of their environment in polymer-inorganic composites is necessary for better understanding of the electron energy transfer processes in a condensed state. From a practical point of view, these materials are promising for optics and medicine. The nanoparticles of ZrO2-LnO1.5 (Ln = Eu, Tb) solid solutions were synthesized by hydrothermal method. The surface functionalization of the obtained nanoparticles by vinyl groups was carried out using 3-(trimethoxysilyl)propyl methacrylate. Soluble and cross-linked composites based on poly(methyl methacrylate) with ZrO2-LnO1.5 nanoparticles were synthesized using radical polymerization in solution and bulk. Molecular weight, thermal stability, and microhardness of the obtained composite materials were determined. The influence of both the polymerization conditions and the forming composite structure on the lanthanide ion photoluminescence in ZrO2 nanoparticles covalently bonded to the polymer matrix was studied. The combination of ZrO2-EuO1.5 and ZrO2-TbO1.5 nanoparticles in the poly(methyl methacrylate) resulted in the production of composites with photoluminescence spectra overlapping the red and green regions of the visible range. It was shown that the structure of the composite affects the absorbing capacity of luminescent centers and allows shifting the excitation spectrum in the longer wavelength region.
关键词： hydrothermal synthesis,poly(methyl methacrylate),rare-earth ions,solid solutions,zirconia,hybrid nanomaterials
更新于2025-09-23 15:21:21
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Schiff base rare earth metal complexes: Studies on functional, optical and thermal properties and assessment of antibacterial activity
摘要： We used the condensation chemistry with anthracene 9 carbaldehyde and 3,4 diaminopyridine to form Schiff base (SB) ligand, N2,N3 bis (anthracen 9 ylmethylene) pyridine 3,4 diamine incorporating Er, Pr and Yb rare earth metals to form a series of SB complexes. Surface, structure, thermal, and optical properties of the resulting complexes were investigated using a variety of tools. The characteristic luminescence properties were observed after rare earth metal inclusions in SB. Antibacterial studies were performed against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa in terms of zone of inhibition for SB complexes. The SB-Pr complexes showed better immune behavior against all the pathogens than the other SB metal complexes.
关键词： Schiff base,Antibacterial,Rare earth metal,Fluorescence,Fourier transform infrared
更新于2025-09-23 15:21:21
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Synthesis and Luminescence Properties of Nanostructured Gd3 –x – yYbxEryBWO9 Borate Tungstates
摘要： Using the Pechini process in the presence of citric acid and mannitol, followed by annealing in the range 800–1000°C, we have synthesized nanostructured rare-earth borate tungstates crystallizing in hexagonal symmetry (sp. gr. P63): undoped Gd3BWO9 and Gd3 – x – yYbxEryBWO9, containing Yb3+ and Er3+ active ions. We have measured upconversion luminescence spectra of the Er3+ ions in Gd3 – x – yYbxEryBWO9 for the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions under excitation by an IR laser (λ = 974 nm). The spectra consist of two groups of broadened bands in the red and green spectral regions. Brighter luminescence is observed in the green spectral region, which contains two bands corresponding to the Er3+ 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions. We have analyzed the effect of annealing temperature on the upconversion luminescence intensity of Gd3 – x – yYbxEryBWO9 and determined the energy yield of upconversion luminescence in the Gd3 – x – yYbxEryBWO9 borate tungstates. The highest value, Ben = 0.19%, has been obtained for the phosphor with Yb : Er = 7 : 1.
关键词： nanophosphors,rare-earth borate tungstates,upconversion phosphors
更新于2025-09-23 15:21:21
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Optical Properties and Electronic Characteristics of Cerium in the Condensed State
摘要： The results of investigating optical properties of metallic cerium in the liquid and solid film state are presented. Optical constants were measured by the ellipsometric Beattie method in the range of 0.42–2.6 μm at ambient temperature. Based on the measured refractive indices and the absorption coefficients, spectra of light conductivity σ, reflectivity R, and characteristic loss function Im ε–1 were calculated. Based on experimental measurements in the IR region, electronic characteristics of liquid cerium and its polycrystalline film and their correlation with electrical conductivity have been determined.
关键词： optical properties,cerium,rare-earth metal,characteristics of conduction electrons,ellipsometry
更新于2025-09-23 15:21:21
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Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes
摘要： We report on the synthesis and photoluminescent performance of the Ba2+ ions doped Eu(HCOO)3 phosphors as well as their promising applications in indoor illumination. The thermal stability of the synthesized sample with microparticles was characterized by the thermogravimetric analysis. Irradiated by 396 nm light, the unique emissions of Eu3+ ions originating from the 5D0 → 7FJ (J ? 1, 2, 3, 4) transitions were observed. With the aid of the Judd-Ofelt theory, the local symmetry properties of the Eu3+ ions in the selected host were studied, revealing that the sites taken by the Eu3+ ions possessed low symmetry with non-inversion center. An enhanced luminescent intensity was seen in the resultant phosphors when the Ba2+ ions were introduced and the optimal doping content was 10 mol%. The studied samples can exhibit bright visible red emission with high color purity of 93.3% upon 396 nm excitation. Moreover, the resistance of the emission intensity to the temperature was also explored and the activation energy was 0.188 eV. Furthermore, the internal quantum efficiency of the resultant samples was 67% when excited by 396 nm. Ultimately, a light-emitting diode (LED) lamp, which emitted warm white light with high color rendering index of 80.7 and low color correlated temperature of 4715 K, was constructed, indicating the feasibility of the synthesized phosphors for white-LED.
关键词： Phosphors,White-LED,Luminescence,Rare-earth ion
更新于2025-09-23 15:21:01
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[IEEE 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Agadir, Morocco (2019.11.27-2019.11.30)] 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Elaboration and Characterization of (Ce,Sm) Doped Lanthanum Oxychloride for Photovoltaic Solar Cell
摘要： The spectral incoherence due to the emission of sunlight and the absorption of silicon solar cells cause large solar energy losses, leading to a low photovoltaic efficiency. So that low energy photons cannot be used efficiently, while the majority of high energy photons are dissipate. Doped rare earth ions (RE) are expected to solve this problem, thanks to their spectral modification characteristics and luminescence properties. In this work we present the synthesis of LaOCl co-doped by trivalent rare earth with the couple of Ce3+/Sm3+ employed in photovoltaic cell down conversion. LaOCl: Ce3+/Sm3+ phosphors were prepared by the solid-state method, and their structures properties were investigated by using X-ray diffraction, Infrared Spectroscopy and MEB analysis. The study shows that tetragonal LaOCl: Ce3+/Sm3+ can be synthesized by the solid-state reaction at 700 °C for 4 h.
关键词： Down conversion,Lanthanum oxychloride,Solid-state,Photovoltaic,Rare Earth
更新于2025-09-23 15:21:01