Rare Earth Fluorescence Research Articles

A Rail-to-Rail Operational Amplifier for Transimpedance Optoelectronic Conversion

The transimpedance conversion circuit is an important part of the fluorescent optical fiber temperature sensor, which is used for rare earth fluorescence detection. Transimpedance conversion circuits can benefit from the wide input range, high gain, low input offset voltage, and high common-mode rejection ratio of rail-to-rail operational amplifiers. In this paper, a constant transconductance rail-to-rail operational amplifier is designed and implemented based on the 0.18 μm CMOS process. According to the simulation results, the transconductance change rate of the operational amplifier is 4.8%, and its gain is 140 dB. The input offset voltage of this operational amplifier is 0.41 μV. Both the power supply rejection ratio and the common-mode rejection ratio have values above 140 dB, with the common-mode rejection ratio reaching as high as 165.4 dB. The transimpedance conversion circuit consists of the operational amplifier designed in this paper. The test results show that the operational amplifier has a certain application value in the transimpedance amplification circuit.

Pulsed laser annealed rare earth doped TiO2 thin films for luminescence and sensing applications

Many research activities target functional luminescent materials based on metal oxides activated with trivalent rare earth ions. Specific applications necessitate optimization of material preparation, annealing and excitation-detection techniques. Hereby we utilized pulsed laser deposition to obtain thin (150 nm) TiO2 films containing 1at% of samarium (Sm) or neodymium (Nd) impurity ions. The effect of pulsed laser annealing (ArF excimer laser, wavelength 193 nm, pulse duration 20 ns) on their structural and luminescent properties was investigated. It was found that, compared to conventional thermal annealing at 700 °C, proper laser annealing (fluence 50 mJ/cm2, 5–15 shots) induced much better crystallization (nearly phase-pure anatase) along with respective improvement of host-sensitized trivalent rare earth fluorescence. The outcome significantly depends on the applied fluence and number of laser shots. Effects of under- and overannealing were witnessed (poor or mixed phase crystallization, weak luminescence and melting/dewetting of the film). A strong luminescence from optimally annealed samples was detected under excitation of 365 nm light emitting diode, which is favorable for potential applications of such thin films. As an example, trace oxygen sensing is demonstrated with the laser annealed TiO2:Sm film.

Detection of malachite green residue in aquaculture water by using a rare earth fluorescence probe

Detection of malachite green residue in aquaculture water by using a rare earth fluorescence probe

Surface radiation-regulation effect in Eu(BA)3Phen doped polyacrylonitrile nanofibers

Electrospun nanofibers of Eu(BA)3Phen doped polyacrylonitrile (PAN) have been prepared and the surface radiation-regulation effect of flexible fibers is revealed. Fluorescence contrast between bulks and nanofibers confirmed that the fibrosis process facilitated spectral reshaping and enhanced energy transfer efficiency of ligands to rare earth ions. Due to the enhanced surface radiation-regulation effect, the quantum efficiency of Eu(BA)3Phen/PAN nanofibers remains on an upward tendency as Eu(BA)3Phen content increasing, and the maximum quantum efficiency of fibers reaches to 86.7%. Large emission cross-section and high radiation transition probability for 5D0 → 7F2 of Eu3+ reach up to 4.043 × 10−21 cm2 and 518.79 s−1, respectively, which indicates that the europium-complexes/PAN nanofibers possess great emissive ability. Accordingly, the nano-sized rare-earth fluorescence materials with high quantum efficiency and excellent flexibility obtained by electrospun fibrosis compensate the brittle defects of bulks, which provides a breakthrough in developing light-converting materials.

Discrete Dipole Approximation Assisted Metal Modulation of Rare Earth Fluorescence and Application

Discrete Dipole Approximation Assisted Metal Modulation of Rare Earth Fluorescence and Application

Rare-earth fluorescence thermometry of laser-induced plasmon heating in silver nanoparticles arrays

The laser-induced plasmon heating of an ordered array of silver nanoparticles, under continuous illumination with an Ar laser, was probed by rare-earth fluorescence thermometry. The rise in temperature in the samples was monitored by measuring the temperature-sensitive photoluminescent emission of a europium complex (EuTTA) embedded in PMMA thin-films, deposited onto the nanoparticles array. A maximum temperature increase of 19 °C was determined upon resonant illumination with the surface plasmon resonance of the nanoarray at the highest pump Ar laser power (173 mW). The experimental results were supported by finite elements method electrodynamic simulations, which provided also information on the temporal dynamics of the heating process. This method proved to be a facile and accurate approach to probe the actual temperature increase due to photo-induced plasmon heating in plasmonic nanosystems.

Fluorescent rare earth solutions as intrinsic wavelength standards for protein fluorescence spectroscopy

Trivalent Gd, Tm, and Dy solutions can be used as intrinsic excitation and emission standards to validate the UV and violet-blue wavelength accuracy of a spectrofluorimeter. Europium extends the range into the red. To attain sufficient sensitivity, these luminescent rare earth ions require deuterated reagents or carbonate complexation, which allow the use of ordinary water and thus preparation in virtually any laboratory. Such solutions are particularly valuable as system suitability standards (SST) for protein fluorescence spectroscopy to detect red shifts of the intrinsic fluorescence maximum in stability and storage studies.

Synthesis and optoelectronic properties of three Eu(III)-dipicolinate complexes based on α-picolinic acid, 2-aminopyridine and 2-hydroxypyridine as secondary ligands

We synthesized some Eu(III) complexes {[Eu(dpa)(α-pc)(CH3OH)]·2CH3OH} (1), {[Eu(dpa)(2-ap)(CH3OH)]·2CH3OH}(2) and {[Eu(dpa)(2-hp)(CH3OH)]·2CH3OH}(3) [dpa = dipicolinic acid; α-pc = α-picolinic acid; 2-ap = 2-aminopyridine; 2-hp = 2-hydroxypyridine]. The structural characterization of the complexes were studied by elemental analysis, FTIR spectroscopy, SEM and powder X-ray diffraction studies (XRD) where the elemental analysis and FTIR results indicate the coordination of ligands with the Eu(III) ion. The X-ray diffraction patterns show the crystalline nature of complex (1) and amorphous nature of complexes (2) and (3) and the SEM micrographs also depict different morphologies of the complexes. The thermal properties of the synthesized complexes were studied by TG–DTA technique which indicates good thermal stability of the synthesized complexes. The optical properties were studied using Ultraviolet visible spectroscopy (UV–Vis) and Photoluminescence studies (PL) where photoluminescence measurements indicate that all the three complexes exhibit the characteristic emission bands of Eu(III) ion corresponding to 5Do → 7FJ (J = 0–4) transitions and it has also been observed that the intensity of emission is influenced by the effect of different secondary ligands. The most intense transition and the long radiative lifetime, quantum efficiency of the 5Do excited level of Eu(III) ion observed for the complex (2) with 2-ap as secondary ligand reflects the good sensitizing ability of ligand 2-ap. The optical properties of the obtained complexes can be well utilized for preparation of rare earth luminescent materials and fluorescence probes.

Photosensitivity in Ce/Sm-decorated Keggin polyoxomolybdates: an interesting photoinduced coloration phenomenon of mixed-metal clusters involving energy transfer from rare-earth fluorescence

Ce/Sm ions are covalently grafted to a Keggin polyoxomolybdate cluster [PMo12O40]3− to yield interesting fluorescent-photodarkening molecular systems. Their photoresponce processes are observed to be activated via energy transfer from luminescent fragments to photocoloration components.

Gilded nanoparticles for plasmonically enhanced fluorescence in TiO2:Sm3+ sol-gel films

Silica-gold core-shell nanoparticles were used for plasmonic enhancement of rare earth fluorescence in sol-gel-derived TiO2:Sm3+ films. Local enhancement of Sm3+ fluorescence in the vicinity of separate gilded nanoparticles was revealed by a combination of dark field microscopy and fluorescence spectroscopy techniques. An intensity enhancement of Sm3+ fluorescence varies from 2.5 to 10 times depending on the used direct (visible) or indirect (ultraviolet) excitations. Analysis of fluorescence lifetimes suggests that the locally stronger fluorescence occurs because of higher plasmon-coupled direct absorption of exciting light by the Sm3+ ions or due to plasmon-assisted non-radiative energy transfer from the excitons of TiO2 host to the rare earth ions.PACS78; 78.67.-n; 78.67.Bf

One‐Step Hydrothermal Synthesis of Carboxyl‐Functionalized Upconversion Phosphors for Bioapplications

In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials.

Tailoring of the spectral–directional characteristics of rare-earth fluorescence by metal–dielectric planar structures

It is demonstrated that the spectrum, direction and polarization of rare-earth fluorescence can be tailored by embedding the impurity ions into a planar metal–dielectric structure (MDS). The latter was designed by spin coating a rare-earth-doped oxide film (TiO2:Sm3+) onto a gold-covered glass substrate. For spectral–directional investigations of Sm3+ fluorescence, the MDS was attached to a semi-cylindrical prism and excited by UV light from the flat side. An angular scan revealed a strongly polarized and directional emission of Sm3+ from the convex side of the prism. The tuning of TiO2 film thickness in the MDS allows a control of the polarization and direction of the emission bands. A theoretical modeling of the reflectivity of the MDS suggests that the observed angular resonances in the fluorescence emission are caused by its effective coupling with surface plasmons on the gold–dielectric interface or coupling with leaky modes in sufficiently thick dielectric films working as a waveguides.

Rare earth doping effect on the optical properties of several fluorescence materials

Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of Y2O2S:Eu using the light source and the feasibility of the system. The rare earth material Y2O2S:Eu is selected as the material candidate for being the most sensitive.

Synthesis and Luminescent Properties of Doped Europium Complexes with 2, 3 - Pyrazine Dicarboxylate

Eleven europium complexes doped other metal ions with 2,3 - pyrazine dicarboxylic acid had been synthesized and characterized by elemental analyses, rare earth EDTA titration, IR, UV and fluorescence spectra. They were EuL1.5•5H2O, Eu0.5Ln0.5 L1.5•5H2O (Ln3+=La3+, Y3+, Gd3+), EuML2.5•8H2O (M2+= Mg2+, Ca2+, Sr2+, Ba2+, Co2+, Ni2+, Zn2+). Doped metal ions could enhanced the fluorescence of Eu3+ complex, and the order of the fluorescence enhancement was Zn2+>La3+>Gd3+>Y3+; Mg2+> Sr2+>Ca2+>Ba2+. And doped with Co2+ and Ni2+ made the Eu3+ luminescence quenched, which the luminous intensity was almost zero.

Synthesis and Characterization of [Eu(DBM)3phen]Cl3@SiO2–NH2 Composite Nanoparticles

Fluorescent rare earth complex Eu(DBM)3(phen)]Cl3@SiO2-NH2 nanoparticles were synthesized by combination of solvent precipitation method and Stöber method. The morphologies, structure, surface and optical properties of the samples were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and fluorescence spectrophotometer (FS). The observation from FE-SEM images indicate that the obtained samples are spherical and uniform nanoparticles with a tunable average sizes from 140 nm to 300 nm. TEM results verify a core-shell structure of the nanoparticles. The FTIR spectrum confirms the characteristic vibration absorption peaks of the complex [Eu(DBM)3(phen)]Cl3@SiO2-NH2. TGA result indicates that the complex is stable below 200 degrees C. The photoluminescence analysis shows that the complex has Eu3+ characteristic red luminescence and broader excitation peak from 200 nm to 450 nm that can meet the demands of fluorescent confocal imaging. The amino groups are directly introduced to the [Eu(DBM)3(phen)]Cl3@SiO2-NH2 nanoparticles surface by using APS (3-aminopropyl triethoxysilane). This makes the surface modification and bioconjugation of the nanoparticles easier. The nano-sized spheres could be provided a basis for further expansion of its application in biomedical imaging, biological detection and fluorescent nanoprobes.

Preparation and Characterization of Ternary Europium Nanorod Complexes with UV Excitation of the Characteristic Red Luminescence

Rare-earth luminescent complex have been attracted increasing interest since they can emit fluorescence using near ultraviolet as excitation wavelength. Nanomaterials have potential applications in optical, electronic, magnetic fields due to their surface effects, volume effects, quantum size effects and macroscopic quantum tunnel effects. Combing the important properties of fluorescence and nanomaterial, the study of nanosized rare earth fluorescence complex is an interesting topic. In this paper, we synthesized ternary luminescence complex nanorods composed of europium (Eu (III))-trimesic acid (H3L)-1,10-phenanthroline (phen) using co-precipitation method in the polyvinylpyrrolidone (PVP) matrix. The elemental analyses of the samples were determined using an Inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the chemical composition PVP/EuL(phen)0.2 5H2O was obtained. The X-ray diffraction (XRD) patterns showed that the resulting nano-sized complex is new substance different from that of two ligands. The transmission electron microscopy (TEM) image indicated that the nano-sized complex was nanorod with the average diameter of about 50 nm. Thermal analysis (TGA) result exhibited that the nano-sized complex is stable under 400 degrees C. UV-Vis diffuse reflectance spectra (DRS) showed that there is the maximum absorption at 260 nm. Photoluminescence analysis (PLA) indicated that the nano-sized complex emits Eu (III) characteristic red luminescence under ultraviolet excitation.

HTRF®: pioneering technology for high-throughput screening

Cisbio international pioneered the field of homogeneous fluorescence methodologies and time-resolved fluorescence resonance in particular, through its proprietary technology, HTRF®. The development was based on Prof. Jean-Marie Lehn’s research on rare earth fluorescence properties (awarded the Nobel Prize in Chemistry in 1987) and on Cisbio’s expertise in homogenous time-resolved fluorescence (HTRF). The technology is used in assay development and drug screening, most notably in high-throughput screening applications. This highly powerful technology is particularly applied to the areas of G-protein-coupled receptor and kinase screening, as well as a series of targets related to inflammation, metabolic diseases and CNS disorders.

Synthesis, Characterization and Fluorescence Properties of Europium, Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu (phen) L 3·1/2H 2O, Eu 0.5RE 0.5(phen)L 3 · 1/2H 2O; Tb(phen) L 3·H2 O and Tb 0.5 RE 0.5 (Phen) L 3·1/2H 2O. (RE = Y 3+, La 3+ and Gd 3+; L = biphenyl 4-carboxylic acid; phen = o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE (III) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu 3+ is raised by inert fluorescent rare earth ions (Y 3+, Gd 3+ and La 3+), but in Tb 3+ hetero-nuclear rare earth complexes the intensity of Tb 3+ ions are quenched by the inert fluorescent rare earth ions.

Site selective excitation in La 2O 3:Eu 3+ nanoparticles

Eu 3+ is a favorite fluorescence probe for studying local structure in solids. In this report, Eu 3+ ions in La 2O 3 nanoparticles were selectively excited; variation of the Eu emission spectra with the excitation wavelengths was observed. It was found that emission spectrum of the Eu ions near the center of the nanocrystals was similar to that of the bulk, where the Eu ions locate at the C 3v symmetry site. By tuning the excitation wavelength, Eu ions in the vicinity of the particle surface may be selectively excited. A gradual variation in emission line positions was observed. Moreover, surface provided an additional non-radiative transition route for the rare-earth fluorescence, shortening the 5D 0 lifetime from 1.25 to 0.87 ms.

Fabrication of Fluorescent Rare Earth Phosphates in Confined Media of Polyelectrolyte Microcapsules

Fluorescent rare earth nanophosphates (La0.95Eu0.05PO4, Ce0.9Tb0.1PO4, and La0.4Ce0.45Tb0.15PO4) were synthesized by reacting the corresponding nitrates exclusively inside PO43- loaded poly(styrene sulfonate)/poly(allylamine hydrochloride) polyelectrolyte capsules of 2.4 μm diameter at room temperature. Crystallization conditions inside the polyelectrolyte capsules lead to the fabrication of crystalline nanoparticles with high fluorescence yield without additional thermal treatment. The fluorescence of these nanoparticles is stable at low and neutral pH. The fluorescent rare earth nanophosphates, fabricated inside polyelectrolyte capsules, were characterized by TEM, SEM, and XRD techniques and fluorescence spectroscopy. Resulting nanophosphates are nanorods ca. 15 nm long and 4 nm in diameter, and they are formed near the inner side of the capsule wall.