Red Emission Of Eu3 Research Articles

Pyrene and Eu3+ modified mesoporous silica used as a fluorescent probe for ratiometric detection of tetracycline antibiotics

The detection of residual tetracycline antibiotics (TCs) in the aquatic environment is important because of the irreversible damage of TCs to the ecosystem and human health. Considering the photostability, sensitivity, and accuracy of the detection systems, mesoporous SBA-15 silica material was an ideal support matrix for improving photostability because it can protect the optical properties of fluorescent signals. To achieve ratiometric detection (with sensitivity and accuracy), pyrene and Eu3+ as two fluorescent signals were implemented into SBA-15, and an organic–inorganic hybrid fluorescent nanoprobe Py/EDTA-SBA-15@Eu3+ was constructed. In the presence of TCs, the red emission of Eu3+ in the nanoprobe was sensitized, and the fluorescence resonance energy transfer occurred from pyrene to Eu3+, resulting in the increased emission of Eu3+ at 617 nm and the decreased emission of pyrene at 384 nm. By monitoring the fluorescent intensity changes at 617 and 384 nm (F617/F384), the nanoprobe achieved the ratiometric detection of oxytetracycline (OTC) and tetracycline (TC) in the range of 0.20–80 and 0.40–80 μM, respectively, with detection limits of 0.18 nM for OTC and 5.83 nM for TC. In addition, the practical application of the nanoprobe was validated in tap water and honey samples.

Fabrication of a ratiometric fluorescence nanoprobe for detecting tryptophan enantiomers

A novel ratiometric fluorescence nanoprobe was developed to detect tryptophan enantiomers with high selectivity and sensitivity. Fluorescein (FL) was doped into SiO2 nanoparticles with little dye leakage, acting as an internal reference signal. The chiral center of L-histidine (L-His) was introduced by partially replacing the carboxyl on the surface of SiO2. The response signal of Eu3+ was coordinated with carboxyl to obtain the FL@SiO2-Eu/His nanoprobe. The nanoprobe shows enantioselective luminescence responses for tryptophan enantiomers. The red emission of Eu3+ can be effectively quenched by the tryptophan enantiomers, but the quenching efficiency is different due to the different interactions with the chiral recognition sites. The fluorescence intensity ratio (I613/I515) shows excellent linearity with tryptophan enantiomers in the range of 0–100 μM (R2 > 0.99). The limit of detection (LOD) is 1.0 μM and 1.3 μM for L-tryptophan (L-Trp) and D-tryptophan (D-Trp), respectively. The FL@SiO2-Eu/His nanoprobe shows good selectivity and specific recognition in serum actual samples. In addition, the nanoprobe can realize visual detection under UV light due to the obvious color change. This work provides an innovative idea for the development of new probes in the detection field.

Fluorescence on and off sensing platform based on europium nanosheets for the detection of DPA and Cu2+ ions.

With the development of society, the modern environment has put forward higher requirements for analysis and detection. This work proposes a new strategy for the construction of fluorescent sensors based on rare-earth nanosheets. Organic/inorganic composites were obtained by the intercalation of 4,4'-stilbene dicarboxylic acid (SDC) into layered europium hydroxide, and then the composites were exfoliated to form nanosheets. Taking advantage of the fluorescence emission characteristics of SDC and Eu3+, a ratiometric fluorescent nanoprobe was constructed, which realized the detection of dipicolinic acid (DPA) and Cu2+ in the same system. With the addition of DPA, the blue emission of SDC gradually decreased and the red emission of Eu3+ gradually increased, when Cu2+ was added, the emission of SDC and Eu3+ were gradually weakened. The experimental results showed that the ratio of fluorescence emission intensity (I619/I394) of the probe had a positive linear relationship with the concentration of DPA, and a negative linear relationship with the concentration of Cu2+, thus realizing the high sensitivity detection of DPA and a wide detection range of Cu2+. In addition, this sensor also exhibits potential visual detection possibilities. This is a multifunctional fluorescent probe that provides a novel and efficient method for the detection of DPA and Cu2+, which broadens the application field of rare-earth nanosheets.

Rapid detection of the biomarker for cystinuria by a metal-organic framework fluorescent sensor

Arginine (Arg) is considered a valuable biomarker for various diseases, including cystinuria, and its concentration level holds significant implications for human health. To achieve the purposes of food evaluation and clinical diagnosis, it is imperative to develop a rapid and facile method for selective and sensitive determination of Arg. In this work, a novel fluorescent material (Ag/Eu/CDs@UiO-66) was synthesized by encapsulating carbon dots (CDs), Eu3+ and Ag + into UiO-66. This material can serve as a ratiometric fluorescent probe for detecting Arg. It exhibits a high sensitivity with a detection limit of 0.74 μM and a relatively broad linear range from 0–300 μM. After dispersing the composite Ag/Eu/CDs@UiO-66 in an Arg solution, the red emission of Eu3+ center at 613 nm was significantly enhanced, while the characteristic peak of CDs center at 440 nm remained unchanged. Therefore, a ratio fluorescence probe could be constructed based on the peak height ratio of the two emission peaks to achieve selective detection of Arg. In addition, the remarkable ratiometric luminescence response induced by Arg results in a significant color transition from blue to red under UV-lamp for Ag/Eu/CDs@UiO-66, which was convenient for visual analysis.

A facile rapid-response and on-site sensor for tetracycline detection in environmental water based on europium-doped carbonized polymer dots

With the increasing concerns about public safety and environmental protection, it is of great significance to establish a rapid and sensitive method to detect antibiotic residues in environmental samples. Herein, fluorescent carbonized polymer dots (CPDs) were synthesized and used for quantitative assay of tetracycline (TC) by chelating with europium ions (Eu3+). The green fluorescence of CPDs could be gradually quenched by TC via inner filter effect and static quenching mechanism, while the red emission of Eu3+ was remarkably enhanced through energy transfer and antenna effect. This ratiometric fluorescence Eu/CPDs-based sensor displayed a wide detection range of 0.05–56, 56–100 μM with a detection limit of 16.4 nM, and was triumphantly applied for TC analysis in water samples with high reliability and accuracy. Moreover, the polymeric structure in CPDs endowed the sensor with good long-term sensing stability up to 600 days. By integrating Eu/CPDs with portable capillary testing kit, a point-of-use device was constructed for facile determination of TC in river water samples with a short sample-to-answer analysis process in 2 min. Due to its easy operation, low-cost, and there is no pretreatment required, the capillary-based testing kit provides a new strategy for on-site and rapid detection of antibiotics in various environmental water samples.

Multicolor fluorescence assay of tetracycline: lanthanide complexed amino clay loaded with copper nanoclusters.

A multicolor fluorescent nanoprobe has been prepared by loading bovine serum albumin-stabilized copper nanoclusters (BSA-Cu NCs) onto amino clay (AC) and grafting Eu3+ with auxiliary ligand citric acid (Cit). Tetracycline (TC) can coordinate with Eu3+ by β-diketone structure and transfer energy to Eu3+ through antenna effect. When the concentration of TC is in the range 0 to 13μM, the blue emission intensity of BSA-CuNCs is basically unchanged, and the red emission of Eu3+ is remarkably enhanced due to the coordination with TC. The emission color gradually changes from blue to red under UV lamp (λ = 365nm). However, when the TC concentration is in the range 13 to 350 μΜ, the internal amino acid residues of BSA sensitize TC, and the emission color gradually changed from red to green. The nanoprobe has rich color, is simple to prepare, portable, and provide a wide detection range. The limit of detection (LOD) is 3.04nM, which could be used for real-time visual analysis of trace TC in actual samples (lake water, milk, honey, and bovine serum albumin). In addition, a visual test paper has been designed and combined with the color scanning APP of a smartphone to complete the qualitative and semi-quantitative test of TC. BSA-Cu NCs were loaded on amino clay and graft Eu3+ to establish ratiometric fluorescent nanoprobe for TC detection. With the increase of TC concentration, the emission color under 365nm UV lamp gradually changed from blue to red and then to green, and the color changed obviously and can be observed by the naked eye. The visual test paper and smartphone application detection sensor were developed to realize rapid, convenient, real-time, and visual detection of TC in actual samples.

The role of modifier oxides on red emission of Eu3+ ions in lithium antimonite glass system

In this study, role of three modifier oxides (viz., MgO, CaO and SrO) on red luminescence efficiency of Eu3+ ions in Sb2O3‒Li2O glass system was investigated. The absorption spectra of these glasses exhibited the bands due to 7F0→ 5D4,3,2,1,0,5G4,2,5L6 and 7F0, 1→7F6 transitions in the visible and NIR regions, respectively. Emission spectra recorded at λexc=394 nm exhibited the bands due to 5D0→7FJ (J = 0 to 4) transitions. Out of these, the band due to5D0→7F2 (red emission ) was found to be more intense. J-O parameters, Ω2 and Ω4 were evaluated using integral R/O ratio of emission spectra. Radiative parameters viz., AR, βR and σEP for Eu3+ions were calculated using J-O parameters, These parameters were observed to be the maximal for SrO mixed glasses. Variations of local symmetry and covalency in the vicinity of Eu3+ ions were found to be responsible for such larger values of these parameters and for intense red emission for SrO mixed glasses.

The effect of GdF3 on red emission of Eu3+: LiYF4 single crystals grown by the Bridgman method

The effect of GdF3 on red emission of Eu3+: LiYF4 single crystals grown by the Bridgman method

Eu3+ and Mn4+ co-doped BaLaMgNbO6 double perovskite phosphors for WLED application

Red light component for white light emitting diodes (WLEDs) keeps attracting the researchers’ attention to obtain high color rendering index (CRI). Here, Eu3+ and Mn4+ co-doped BaLaMgNbO6 double perovskite red phosphors were acquired by solid-state reaction method. Both the red emission of Eu3+ and deep-red emission of Mn4+ could be realized under the excitation of near ultraviolet light. The concentrations of Eu3+ and Mn4+ in BaLaMgNbO6 were optimized to be 30.0 mol% and 0.1 mol%, respectively. Temperature dependent emission of Eu3+ and Mn4+ were carried out to reveal the thermal stability of this red phosphor. Optimized BaLa0.7Eu0.3MgNb0·999Mn0·001O6 was mixed with commercial blue and green phosphors to obtain WLEDs. The CRI of the fabricated device reaches 90.2, confirming this red phosphor an excellent candidate as red light compensation for WLEDs.

A Fluorescent Nanosensor for Silver (Ag+) and Mercury (Hg2+) Ions Using Eu (III)-Doped Carbon Dots.

Carbon dots doped with Eu3+ ions (Eu-Cdots) were prepared by a hydrothermal treatment, using citric acid and urea as precursors and Eu (NO3)3 as a europium source. The Eu3+ ions are strongly coordinated with the carboxylate groups at the surface of the Cdots and incorporated within the nanographene network in the carbon core. Vibrational spectroscopy provides evidence of such interaction with identification of bands assigned to the stretching of the Eu-O bond. Eu3+ doped Cdots have larger diameters then undoped Cdots, but they are divided into smaller domains of sp2 carbon. The UV-vis excitation spectrum provides evidence of energy transfer from the Cdots to the Eu3+. The luminescence spectrum shows the characteristic sharp peaks of Eu3+ in the red part of the visible spectrum and a broad emission of Cdots centered at 450 nm. The luminescence of the Cdots is strongly quenched by Hg2+ and Ag+, but not by other cations. The quenching mechanism differs significantly depending on the nature of the ion. Both the blue emission of Cdots and the red emission of Eu3+ are quenched in the presence of Hg2+ while only the emission of the Cdots is affected by the presence of Ag+. A ratiometric sensor can be built using the ratio of luminescence intensities of the Cdots to the Eu3+ peaks.

Achieving tunable luminescence in Eu2+ and Eu3+ codoped MAl2B2O7:Eu (M = Ca2+, Sr2+, and Ba2+) phosphor by structure defect designing and site symmetry controlling

Eu2+ and Eu3+ codoped alkaline-earth aluminum borates MAl2B2O7:Eu (M = Ca2+, Sr2+, and Ba2+) phosphors were prepared by a conventional high-temperature solid-state method. The phosphor exhibits strong absorption in the spectral range of ∼200–450 nm and bright tunable emission in the blue region, white region, and red region. The effect of composition, excitation wavelength, and doping concentration of europium ion on luminescence behavior of the phosphors were investigated systematically. Upon 254 nm excitation, SrAl2B2O7:Eu exhibits blue and bluish-green emission of Eu2+ and red emission of Eu3+. Ca2+ substitution for Sr2+ promoted the optimization of luminescence quality, and even the emergence of white light with chromatic coordination (0.382, 0.234), and Ba2+ substitution for Sr2+ increased the total luminescence intensity by ∼12.5 times. The changes in luminescence behavior were explained according to the structural defect of the phosphor and the site symmetry of the europium ions. The tunable luminescence and white-light emission upon 254 nm excitation imply that the phosphors have potential application prospects in cold cathode fluorescent lamps.

A novel core-shell nanomaterial ratiometric fluorescent probe for detecting urinary TDGA as a biomarker for VCM exposure

Thiodiglycolic acid (TDGA) is regarded as a sensitive biomarker for biological monitoring of VCM exposure. A simple, fast and reliable TDGA analysis method is of great significance to human health and the ecological environment. In this work, a novel core-shell nanomaterial based on p-type semiconductor@MOFs (Eu-CBO@Uio-66) is first prepared by in-situ growth and post-synthesis modification (PSM) as a ratiometric fluorescent probe for detecting TDGA, which shows a high sensitivity with a detection limit down to 51.1 μg L−1 (about 0.34 μM), relatively broad linear range (0–700 mg/L), fast response to TDGA within 2 min. As a result, after dispersing the resulting composite material in a solution containing TDGA, the blue emission of Eu-CBO@Uio-66 at 466 nm remains unchanged, while the red emission of Eu3+ center at 615 nm is significantly quenched, even in coexistence with other potentially analytes in the urine, so that the peak height ratio of the two emissions could be employed for determining TDGA. In addition, the significant ratiometric luminescence response caused by TDGA makes Eu-CBO@Uio-66 undergo a significant color transition from red to blue under UV-lamp, which is beneficial for visual analysis with the naked eye.

Efficient white upconversion luminescence in Yb3+/Eu3+ doubly-doped transparent glass ceramic.

Efficient white upconversion (UC) luminescence is obtained in Yb3+/Eu3+ doubly-doped optical glass ceramic (GC) for the first time. KYb3F10 nanocrystals are controllably precipitated from the amorphous networks via the inducing of Yb3+. Yb3+ ions are spontaneously confined within the compact fluoride crystal structures to produce efficient blue UC emissions of Yb3+-Yb3+ pairs. Eu3+ ions are easily incorporated into the KYb3F10 crystal lattices. Owing to the extremely short interionic distance in the crystal structures, intense green UC emissions apart from the red emissions of Eu3+ are observed, which are not obtained by the traditional Yb3+/Eu3+ doubly-doped GCs. As a result, white UC emissions are synthesized based on the three-primary-color principle and the emission intensities of GCs are dramatically enhanced as compared to glass. The designed GCs provide novel optical gain materials for the promising applications in three-dimensional display, solid-state lighting and tunable fiber lasers.

Luminescent properties of Eu3+ doped germanosilicate red glass

Eu3+ doped germanosilicate red glass was prepared by traditional high temperature melting method. The structure and optical properties of the samples were characterized by X-ray diffraction, photoluminescence spectra, Fourier transform infrared spectroscopy, absorption spectra, fluorescence decay time and CIE chromaticity coordinates. The density of the samples was measured. The band gap of the samples and the spacing of the doped rare earth ions were calculated theoretically. It is shown that the red emissions of Eu3+ at 589 nm and 614 nm are the main emissions in visible wavelengths, and the optimal concentration is 2.0 mol%, when the Eu3+ spacing is 10.337 Å. With the increase of Eu3+ concentration, the general trend of indirect and direct band gaps decreased from 3.977 eV to 2.952 eV and 3.501 eV to 2.577 eV, respectively. The [GeO4] tetrahedron, [GeO6] octahedron and [GeO4]&[SiO4] co-exist in the glass network structure, and the change of Eu2O3 concentration has a certain influence on the glass structure. All the samples emit light in the red region. The color temperature of the prepared glass is between 1859 and 2123 K under the excitation of ultraviolet light at 394 nm, and the color purity is all above 80%.

Scattering-promoted plasmonic enhancement of Eu3+ ions photoluminescence in dichroic Cu nanocomposite glass

The red emission of Eu3+ ions embedded in glasses containing copper with distinct plasmonic properties is reported. Either a photoluminescence (PL) enhancement or quenching is manifested depending on whether the nanocomposite is dichroic (scatters red but transmits blue) or not (ruby-colored). In addition, Eu3+ emission in the dichroic glass is indicated to be either enhanced or quenched depending on the excitation wavelength. The glasses consisting of barium–phosphate matrix co-doped with Cu and Eu were obtained by thermal processing. Characterizations were then performed by Fourier transform-infrared spectroscopy, UV/Vis optical absorption, PL spectroscopy with decay dynamics assessment, and light scattering measurements. The latter were conducted for the first time on plasmonic metal nanocomposite glasses, aiming to clarify the origin of the distinct optical properties. It is supported that favorable conditions for the PL enhancement are achieved when the emission of Eu3+ ions can benefit from light scattering by plasmonic Cu particles. However, an excitation energy transfer from Eu3+ to Cu nanoparticles via interband transitions leading to the PL quenching should be minimized.

Reversible conversion of the valence states of Eu ions in ABaPO4 (A = Li, Na, and K) in terms of change in luminescence property

We investigated the emission properties of Eu ion-doped ABaPO4 (ABaPO4:Eu, A = Li, Na, and K) in which the valence state of the Eu ions was controlled by annealing in various ambients, gamma-ray (γ-ray) irradiation, and hydrogen ion (H+) implantation. We synthesized the ABaPO4:Eu samples by solid-state reaction in air. The as-synthesized samples showed sharp red emission near 600 nm, which originated from Eu3+ ions. Interestingly, annealing under H2 ambient changed the valence state of the Eu ions from 3+ to 2+, which was indicated by the disappearance of the red emission and concurrent emergence of strong blue emission. After subsequent annealing in O2 atmosphere, the red emission of Eu3+ was recovered. The reversible switching between the 2+ and 3+ states was found to be repeatable by alternating H2 and O2 annealing. The valence state was also changed from 3+ to 2+ by H+ implantation and γ-ray irradiation of the as-synthesized samples, possibly owing to the formation of oxygen vacancies. Our results suggest that the luminescence color of the ABaPO4:Eu phosphors can be controlled within a range from red to blue by simple annealing in various ambients.

Observation of energy transfer from Eu2+ to Eu3+ and tunable luminescence in phosphors YF3:Eu prepared by hydrothermal method

Eu2+ and Eu3+ co-activated YF3:Eu phosphors were prepared by a traditional hydrothermal method with citric acid as reducing agent. Products with bitter gourd like morphology comprised of numerous nanoparticles show a blue emission of Eu2+ and a red emission of Eu3+ simultaneously. The relative amount of Eu2+ and Eu3+ can be tuned by adjusting Eu concentration, citric acid concentration and hydrothermal reaction time. Obvious energy transfer from Eu2+ to Eu3+ can be observed. Through energy transfer, Eu2+ and Eu3+ can be effectively excited by the ultraviolet light in the range of 275–400 nm and a tunable luminescence color from red, white to blue can be achieved. The work will provide an alternative solution for the development of new LED phosphors.

The influence of the complexing agent on the luminescence of multicolor-emitting Y2O3:Eu3+,Er3+,Yb3+ phosphors obtained by the Pechini's method

In this study, it is reported the enhancement of the downshifting and the upconversion emission of Y2O3:Eu3+,Er3+,Yb3+ phosphor drove by sorbitol instead of the classic ethylene glycol used as polymerizing agent in the Pechini's synthesis. The RE3+ doping concentration was also varied to optimize the red or the green Er3+ emission or the Eu3+ red emission. Phosphors were obtained as high-crystalline and micro-sized particles, yet the doping concentration and the polymerizing agent influence the crystallite size and the lattice strain of the Y2O3 matrix that features optical band gap near to 5.6 eV. Under excitation at 378 nm, the downshifting emissions of Eu3+ and Er3+ are noticed, but under excitation at 463 nm, only the typical Eu3+ emission in the red spectral region is viewed. Contrarily, by exciting the phosphors at 980 nm within the IV spectral region, both green and red emissions of Er3+ plus the red emission of Eu3+ are seen through upconversion emission, and in this case, the pair Er3+/Yb3+ acts as sensitizers to the Eu3+ luminescence. Moreover, the use of sorbitol instead of ethylene glycol in the Pechini's synthesis enhances both downshifting and upconversion luminescence of phosphors due to a lowering of the Eu3+ local microssymmetry played by sorbitol, accordingly to the analyses of Judd-Ofelt intensity parameters of the phosphors. Finally, by varying the doping concentration, the polymerizing agent, and the excitation wavelength, the phosphor emission color may be tuned from the green towards the red spectral region.

Synthesis and Red Emission of Eu3+-DOPED NaLaMo2O8 Phosphors

Eu3+-doped NaLaMo2O8 phosphors were synthesized by a conventional solid-state reaction. The phase and luminescent properties of the synthesized phosphors were investigated in the current work. In NaLaMo2O8, Eu3+ ions replace La3+ ions and form solid compound. This substitution induces the 2θ angles of diffraction peaks to shift to larger values. Under excitation at 395 nm, NaLaMo2O8:Eu3+ phosphors exhibit emission bands in the range of 550–725 nm originating from 5D0 → 7FJ transitions (J = 0, 1, 2, 3, 4) of Eu3+. The strongest emission band corresponds to the 5D0 → 7F2 transition, which indicates a site of Eu3+ without inversion symmetry in NaLaMo2O8. The Eu3+ concentration has obvious influence on the luminescent properties of NaLaMo2O8:Eu3+ phosphors. NaLaMo2O8:6 mol%Eu3+ has the strongest excitation and emission intensities.

Optical properties of the CaEuAl3O7 phosphor with dual‐activator Eu2+/Eu3+ for multifunctional applications

AbstractAt present, most blue‐red composite LED light sources are widely used in the field of plant lighting. However, their full‐width at half‐maximum of blue light is too small to meet the requirements of plants for photosynthesis. Herein, a dual‐emitting single‐phase self‐luminescent phosphor CaEuAl3O7 (CEAO) is reported in this study, which provides broadband blue emission of Eu2+ ions and red emissions of Eu3+ ions. According to the optical properties of Eu2+ and Eu3+ ions in the CEAO phosphor, it can be found that all emissions are consistent with the absorption of chlorophylls and pigment carotenoids. In addition, the temperature sensing based on the fluorescence intensity ratio (FIR) in the CEAO phosphor is also studied and the maximum sensitivity (S) can reach as high as 6.90% K−1 at 313 K. The results indicate that the single‐component phosphor CEAO with blue and red double‐color emission possesses an outstanding potential in plant growth lamps and optical thermometry applications.