Lanthanide-based luminescent hybrid materials.

Interpretation of europium(III) spectra

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

http://library.um.ac.id/free-contents/downloadpdf.php/buku/complexation-reactions-in-aquatic-systems-an-analytical-approach-j-buffle-translators-s-p-kounaves-a-kounaves-and-r-s-altman-12623.pdf

Complexation reactions in aquatic systems : an analytical approach / J. Buffle, translators S.P. Kounaves, A. Kounaves and R.S. Altman

Quantum dots (QDs) have received great interest for diverse applications due to their distinct advantages, such as narrow and symmetric emission with tunable colors, broad and strong absorption, reasonable stability, and solution processibility Doped QDs not only potentially retain almost all of the above advantages, but also avoid the self-quenching problem due to their substantial ensemble Stokes shift Two obvious advantages of doped QDs, especially doped ZnS QDs, over typical CdSe@ZnS and CdTe QDs are longer dopant emission lifetime and potentially lower cytotoxicity The lifetime of dopant emission from transition-metal ion or lanthanide ion-doped QDs is generally longer than that of the bandgap or defect-related emission of host, and that of biological background fluorescence, providing great opportunities to eliminate background fluorescence for biosensing and bioimaging For bioimaging applications, fluorescent dopants may mitigate toxicity problems by producing visible or infrared emission in nanocrystals made from less-harmful elements than those currently used In this review, recent advances in utilizing doped QDs for chemo/biosensing and bioimaging are discussed, and the synthetic routes and optical properties of doped QDs that make them excellent probes for various strategies in chemo/biosensing and bioimaging are highlighted Moreover, perspectives on future exploration of doped QDs for chemo/biosensing and bioimaging are also given

Doped quantum dots for chemo/biosensing and bioimaging

Herein, we report the synthesis, structural investigation, and magnetic and photophysical properties of a series of 13 [ZnIILnIII] heterodinuclear complexes, which have been obtained employing a Sc...

Study of the luminescent and magnetic properties of a series of heterodinuclear [Zn(II)Ln(III)] complexes.

High-resolution optical spectroscopy of YAG:Nd: A test for structural and distribution models.

The synthesis, structural investigation, and photophysical properties of a new heterobinuclear complex, [Zn(H(2)O)(valpn)Eu(NO(3))(3)], are reported [H(2)valpn = 1,3-propanediylbis(2-iminomethylene-6-metoxy-phenol)]. In the absence of the antenna-type sensitization of europium emission at room temperature, the strongest metal-centered emission was obtained following excitation into the (7)F(0)-(5)D(2) transition at 535 nm. In contrast, at 80 K, the strongest emission of europium was obtained by exciting into the maximum of a high-intensity, low-lying ligand-to-metal charge-transfer band (LMCT) located at approximately 425 nm. The overall temperature-induced changes of the photophysical properties of europium were assigned to the relative location of the LMCT and (3)pi pi* ligand states to the europium excited levels. The results may explain the lack of the antenna effects reported for some of the europium complexes with this type of ligand.

Temperature Switch of LMCT Role: From Quenching to Sensitization of Europium Emission in a ZnII−EuIII Binuclear Complex

Pure and europium (Eu3+) doped cerium dioxide (CeO2) nanocrystals have been synthesized by a novel oil-in-water microemulsion reaction method under soft conditions. In-situX-ray diffraction and RAMAN spectroscopy, high-resolution transmission electron microscopy, UV/Vis diffuse-reflectance and Fourier transform infrared spectroscopy as well as time-resolved photoluminescence spectroscopy were used to characterize the nanaocrystals. The as-synthesized powders are nanocrystalline and have a narrow size distribution centered on 3 nm and high surface area of ∼250 m2 g−1. Only a small fraction of the europium ions substitutes for the bulk, cubic Ce4+ sites in the europium-doped ceria nanocrystals. Upon calcination up to 1000 °C, a remarkable high surface area of ∼120 m2 g−1 is preserved whereas an enrichment of the surface Ce4+ relative to Ce3+ ions and relative strong europium emission with a lifetime of ∼1.8 ms and FWHM as narrow as 10 cm−1 are measured. Under excitation into the UV and visible spectral range, the europium doped ceria nanocrystals display a variable emission spanning the orange-red wavelengths. The tunable emission is explained by the heterogeneous distribution of the europium dopants within the ceria nanocrystals coupled with the progressive diffusion of the europium ions from the surface to the inner ceria sites and the selective participation of the ceria host to the emission sensitization. Effects of the bulk-doping and impregnation with europium on the ceria host structure and optical properties are also discussed.

Surface versus volume effects in luminescent ceria nanocrystals synthesized by an oil-in-water microemulsion method

Despite considerable research, the location of an aliovalent dopant into SnO2 nanoparticles is far to be clarified. The aim of the present study on trivalent lanthanide doped SnO2 is to differentiate between substitutional versus interstitial and surface versus bulk doping, delineate the bulk and surface defects induced by doping and establish an intrinsic dopant distribution. We evidence for the first time a complex distribution of intrinsic nature composed of substitutional isolated, substitutional associates with defects as well as surface centers. Such multi-modal distribution is revealed for Eu and Sm, while Pr, Tb and Dy appear to be distributed mostly on the SnO2 surface. Like the previously reported case of Eu, Sm displays a long-lived luminescence decaying in the hundreds of ms scale which is likely related to a selective interaction between the traps and the substitutional isolated center. Analyzing the time-gated luminescence, we conclude that the local lattice environment of the lattice Sn is not affected by the particle size, being remarkably similar in the ~2 and 20 nm particles. The photocatalytic measurements employed as a probe tool confirm the conclusions from the luminescence measurements concerning the nature of defects and the temperature induced migration of lanthanide dopants.

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Carmen Tiseanu

Papers

Study of the luminescent and magnetic properties of a series of heterodinuclear [Zn(II)Ln(III)] complexes.

High-resolution optical spectroscopy of YAG:Nd: A test for structural and distribution models.

Temperature Switch of LMCT Role: From Quenching to Sensitization of Europium Emission in a ZnII−EuIII Binuclear Complex

Surface versus volume effects in luminescent ceria nanocrystals synthesized by an oil-in-water microemulsion method

Nanoscale insights into doping behavior, particle size and surface effects in trivalent metal doped SnO 2