The radiative and nonradiative decay rates of lissamine dye molecules, chemically attached to differently sized gold nanoparticles, are investigated by means time-resolved fluorescence experiments. A pronounced quenching is observed already for the smallest nanoparticles $1\text{ }\text{ }\mathrm{n}\mathrm{m}$ radius. caused not only an increased rate but, equally important, a drastic decrease in dye's rate. Assuming resonant energy transfer be responsible channel, we compare our...

In this communication we describe a technique for measuring the absolute quantum yields (QYs) of upconverting nanomaterials based on use commercially available fluorimeter and an integrating sphere. Using setup, have successfully acquired luminescence efficiency data (pump laser, absorbed pump, visible emitted intensities) lanthanide-doped nanoparticles. QYs in range 0.005% to 0.3% were measured several NaYF4: 2% Er3+, 20% Yb3+ nanoparticles with particle sizes ranging from 10 100 nm while...

Nanoparticles of LaF3 doped with Ln3+ (Ln = Eu, Er, Nd, and Ho) have been prepared that are dispersible in organic solvents. From the spectrum Eu3+ it has concluded dopant ion occupies a La3+ site. The luminescence decays fitted biexponentially. A given possible explanation for this is different probability nonradiative decay ions at or near surface core particles. lifetimes doping concentration 5% were 7.7 ± 0.2 2.9 ms, indicative very high quantum yields. particles Er3+, Nd3+, Ho3+...

White light was generated from a single silica thin film made with Yb0.75La0.2Eu0.05F3, La0.45Yb0.5Er0.05F3, and La0.75Yb0.2Tm0.05F3 nanoparticles by exciting source near-infrared (980 nm CW diode laser). Eu3+ Tm3+ ions are responsible for red blue emission, respectively. Er3+ ion is green as well emission. The Commission Internationale de l'Eclairage (CIE) coordinates of the resulting were easily adjusted controlling concentration Ln3+ (Eu3+, Er3+, Tm3+) in Ln3+-doped sol−gel layer.

We present a technique for the replacement of oleate with PEG−phosphate ligand [PEG = poly(ethylene glycol)] as an efficient method generation water-dispersible NaYF4 nanoparticles (NPs). The ligands are shown to exchange original on surface NPs, resulting in NPs. upconversion intensity NPs aqueous environments was found be severely quenched when compared organic solvents. This is attributed increase multiphonon relaxations lanthanide excited state due high energy vibrational modes water...

We report on the size-tunable synthesis of thermodynamically stable (β) NaGdF4 nanoparticles (NPs) below 10 nm. Paramagnetic β-NaGdF4 NPs four different sizes (2.5–8.0 nm with a narrow size distribution) were synthesized by simple modifications reaction conditions affecting nanoparticle growth dynamics. The transferred to water exchanging oleate ligands biocompatible polyvinylpyrrolidone, and analyzed for their ability affect magnetic resonance (MR) T1 longitudinal relaxivity at 1.5 T. ionic...

We demonstrate a novel epitaxial layer-by-layer growth on upconverting NaYF4 nanocrystals (NCs) utilizing Ostwald ripening dynamics tunable both in thickness and composition. Injection of small sacrificial NCs (SNCs) as shell precursors into larger core results the rapid dissolution SNCs their deposition onto to yield core–shell structured NCs. Exploiting this NC size dependent dissolution/growth, can be controlled either by manipulating number injected or successive injection SNCs. In these...

In this work, we report the multifunctional character of neodymium-doped LaF3 core/shell nanoparticles. Because spectral overlap neodymium emission bands with transparency windows human tissues, these nanoparticles emerge as relevant subtissue optical probes. For contents optimizing luminescence brightness Nd3+:LaF3 nanoparticles, penetration depths several millimeters have been demonstrated. At same time, it has found that infrared show a remarkable thermal sensitivity, so they can be...

The preparation of nearly monodisperse (40 nm), silica-coated LaF(3):Ln(3+) nanoparticles and their bioconjugation to FITC-avidin (FITC=fluorescein isothiocyanate) is described in this report. Doping the LaF(3) core with selected luminescent Ln(3+) ions allows particles display a range emission lines from visible near-infrared region (lambda=450-1650 nm). First, use Tb(3+) Eu(3+) resulted green (lambda=541 nm) red (lambda=591 612 emissions, respectively, by energy downconversion processes....

Sensors based on self-assembled monolayers (SAMs) are the topic of this article. First an overview analytical techniques used for characterization is given. This followed by details use functional SAMs to study interactions with analytes, example, complexation metal ions crown ether adsorbates.

Optical waveguide amplifiers based on polymer materials offer a low-cost alternative for inorganic amplifiers. Due to the fact that their refractive index is similar of standard optical fibers, they can be easily coupled existing fibers with low coupling losses. Doping rare-earth ions yield gain not straightforward, as salts are poorly soluble in matrix. This review article focuses two different approaches dope ions. The first approach organic cage-like complexes encapsulate ion and designed...

Surface-coated nanoparticles of LaF3 and LaPO4 doped with the luminescent trivalent lanthanide ions Eu3+, Nd3+, Er3+, Pr3+, Ho3+, Yb3+ have been prepared. These emit in visible near-infrared part electromagnetic spectrum. The Ho3+ are main focus this research because they show emissions telecommunication windows. ion is interest it can be used as a sensitizer for Er3+. Eu3+ has probe structural environment ion. It shown that these incorporated inorganic host particles dispersable organic...

m-Terphenyl-based lanthanide complexes functionalized with a triphenylene antenna chromophore ((Ln)1) exhibit sensitized visible and near-infrared emission upon photoexcitation of the at 310 nm.Luminescence lifetime measurements (Eu)1 (Tb)1 in methanol-h 1 methanol-d revealed that one methanol molecule is coordinated to ion, indicating all eight donor atoms provided by ligand are involved encapsulation ion.The luminescence lifetimes near-IR-emitting (Er)1, (Nd)1, (Yb)1 DMSO-h 6 DMSO-d...

Nanoparticles consisting of either a solid core GdF3 or an 80/20 mixture and LaF3 have been prepared for use as NMR MRI relaxation agents. To obtain high aqueous solubilities, the particles were coated with citrate (cit) groups (in case nanoparticles), giving nanoparticle negatively charged surface, 2-aminoethyl phosphate (AEP) GdF3/LaF3 = 80/20), positively surface at physiological pH. In presence GdF3/LaF3:AEP, paramagnetic contribution to water spin−lattice rate was observed be 7.5 s-1...

Hexagonal-phase NaYF(4)/NaGdF(4) core/shell nanocrystals were synthesized and investigated by X-ray photoelectron spectroscopy (XPS) using tunable synchrotron radiation. Based on the ratio of Y(3+) 3d to Gd(3+) 4d core level intensities at varying kinetic energies, we conclude that resides predominantly surface nanocrystals, proving a structure. These show potential for use as contrast agents in magnetic resonance imaging (MRI) applications optical imaging.

Three different broadband sensitization concepts for optically active erbium ions are reviewed: 1) silicon nanocrystals, with absorption over the full visible spectrum, efficiently couple their excitonic energy to Er3+, 2) silver-related defect states in sodalime silicate glass have blue and transfer 3) organic cage complexes coordinated well-chosen chromophores serve as sensitizers visible. Energy rates, efficiencies, limiting factors addressed each of these sensitizers. Implications use...

The surface of lanthanide(III)-doped LaPO4 nanoparticles was modified by reaction with an alcohol, leading to a covalent bond between the ligand and particle surface. LaF3 alter solubility study influence effects on luminescence lanthanide ions doped in nanoparticles. coordinated organic ligands can be quantitative exchange solution or using functionalized during synthesis. Variation ratio core reagents had significant size Smaller were formed higher ratio. optical properties these show...

Distinct surface effects on the luminescence properties of highly crystalline LaF3:Eu nanoparticles have been demonstrated, by incorporating different ligands their as well forming core–shell (i.e. doped core with an undoped LaF3 shell). These studies established that Eu3+ ions a less symmetric crystal field than “bulk”, and they are responsible for ligand induced changes in asymmetric ratio, which is determined from relative intensity ratio 5D0 → 7F2 (612 618 nm) 7F1 (591 transitions. This...

A facile ligand-exchange strategy with a water-soluble polymer, i.e. polyvinylpyrrolidone (PVP), to replace the surface passivating oleate ligands on β-NaYF4 nanoparticle is reported. Highly monodisperse oleate-stabilized nanoparticles were synthesized and oleates exchanged commercially available PVP allowing phase transfer of these nanoparticles. The are readily dispersible in water other polar solvents. To show effectiveness exchange reaction we used affinity chains silica coated uniform,...

Bright green and red luminescence has been generated with a 980 nm diode laser from silica sol−gel thin films made La0.45Yb0.50Er0.05F3 nanoparticles through newly described hetero-looping-enhanced energy-transfer (hetero-LEET) up-conversion process, which exhibits power dependence similar to that of photon avalanche (PA). The hetero-LEET mechanism is potentially more efficient than PA, ground-state absorption/excited-state absorption (GSA/ESA), (ETU) mechanisms because it combines resonant...

The future perspective of fluorescence imaging for real in vivo application are based on novel efficient nanoparticles which is able to emit the second biological window (1000–1400 nm). In this work, potential Nd 3+ ‐doped LaF 3 (Nd :LaF ) reported bioimaging both first and windows their three main emission channels ions: 4 F 3/2 → I 9/2 , 11/2 13/2 that lead emissions at around 910, 1050, 1330 nm, respectively. By systematically comparing relative intensities, penetration depths subtissue...

Photoluminescent, near-stoichiometric colloidal CuInSe2 nanocrystals are synthesized in large batches and with good quality. An organometallic method is used a moderate reaction temperature (≤200 °C) to produce size-tunable photoluminescence spectra ranging from ∼600 ∼850 nm. Two-dimensional excitation–emission maps reported for the nanocrystals, highlighting excitonic features. Type I heterostructured CuInSe2/ZnS prepared purified. They found have absolute quantum yields up ∼26%. The...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCocomplexation of neutral guests and electrophilic metal cations in synthetic macrocyclic hostsCatherina J. Van Staveren, Johan. Eerden, Frank C. M. Veggel, Sybolt. Harkema, David N. ReinhoudtCite this: Am. Chem. Soc. 1988, 110, 15, 4994–5008Publication Date (Print):July 1, 1988Publication History Published online1 May 2002Published inissue 1 July 1988https://pubs.acs.org/doi/10.1021/ja00223a017https://doi.org/10.1021/ja00223a017research-articleACS...