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Upconversion Emission (upconversion + emission)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

Blue, Green, and Red Upconversion Emission from Lanthanide-Doped LuPO4 and YbPO4 Nanocrystals in a Transparent Colloidal Solution.

CHEMINFORM, Issue 41 2003
Stephan Heer
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln3+ -Doped Gd2O3 Nanotubes

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2010
Andreia G. Macedo
Abstract There is a growing interest in understanding how size-dependent quantum confinement affects the photoluminescence efficiency, excited-state dynamics, energy-transfer and thermalization phenomena in nanophosphors. For lanthanide (Ln3+)-doped nanocrystals, despite the localized 4f states, confinement effects are induced mostly via electron,phonon interactions. In particular, the anomalous thermalization reported so far for a handful of Ln3+ -doped nanocrystals has been rationalized by the absence of low-frequency phonon modes. This nanoconfinement may further impact on the Ln3+ luminescence dynamics, such as phonon-assisted energy transfer or upconversion processes. Here, intriguing and unprecedented anomalous thermalization in Gd2O3:Eu3+ and Gd2O3:Yb3+,Er3+ nanotubes, exhibiting up to one order of magnitude larger than previously reported for similar materials, is reported. This anomalous thermalization induces unexpected energy transfer from Eu3+C2 to S6 crystallographic sites, at 11,K, and 2H11/2,,,4I15/2 Er3+ upconversion emission; it is interpreted on the basis of the discretization of the phonon density of states, easily tuned by varying the annealing temperature (923,1123,K) in the synthesis procedure, and/or the Ln3+ concentration (0.16,6.60%). [source]

Upconverting Nanoparticles: The Active-Core/Active-Shell Approach: A Strategy to Enhance the Upconversion Luminescence in Lanthanide-Doped Nanoparticles (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009
Mater.
Lanthanide-doped nanoparticles capable of (up)converting near-infrared (NIR) light to higher energies via an anti-Stokes process known as upconversion have demonstrated extraordinary potential in biological applications on the virtue that background fluorescence is near-zero. To maximize the intensity of the upconverted luminescence in lanthanide-doped nanoparticles, Vetrone et al. utilize a core/active-shell architecture where the active-shell readily absorbs NIR light and transfers it to the active luminescent core, thereby increasing the upconversion emission, as described on page 2924. [source]

Synthesis and Optical Properties of KYF4/Yb, Er Nanocrystals, and their Surface Modification with Undoped KYF4,

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2008
Helmut Schäfer
Abstract KYF4/Yb3+, Er3+ nanocrystals with a mean diameter of approximately 13,nm were synthesized at 200,°C in the high boiling organic solvent N -(2-hydroxyethyl)ethylenediamine (HEEDA). The particles crystallize in the cubic phase known from , -NaYF4 and form transparent colloidal solutions in tetraethylene glycol (TEG) or propanol. Solutions containing 1,wt % of the nanocrystals in TEG display visible upconversion emission upon continuous wave (CW) excitation at 978,nm. Growing undoped KYF4 on the surface of the KYF4/Yb3+, Er3+ nanocrystals increases the upconversion efficiency by more than a factor of 20. The XRD data of these particles, display a slight increase in the mean particle size from 13 to 15.5,nm, indicating that only a part of the subsequently added KYF4 shell material is deposited onto the particle surface. Nevertheless the performed surface modification obviously leads to core/shell structured particles. [source]

Luminescence Modulation of Ordered Upconversion Nanopatterns by a Photochromic Diarylethene: Rewritable Optical Storage with Nondestructive Readout

ADVANCED MATERIALS, Issue 5 2010
Chao Zhang
Inorganic,organic composite films for rewritable optical storage are fabricated base on the reversible luminescence modulation of ordered upconversion nanopatterns via a photochromic diarylethene. The near-IR excitation for reading the upconversion emission does not affect the recorded data bits. Moreover, the spatially well-defined 2D nanopatterns promise future applications in ultrahigh-density storage. [source]

Luminescence of Nanocrystalline Erbium-Doped Yttria

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
Yuanbing Mao
Abstract In this paper, the luminescence, including photoluminescence, upconversion and cathodoluminescence, from single-crystalline erbium-doped yttria nanoparticles with an average diameter of 80,nm, synthesized by a molten salt method, is reported. Outstanding luminescent properties, including sharp and well-resolved photoluminescent lines in the infrared region, outstanding green and red upconversion emissions, and excellent cathodoluminescence, are observed from the nanocrystalline erbium-doped yttria. Moreover, annealing by the high power laser results in a relatively large increase in photoluminescent emission intensity without causing spectral line shift. These desirable properties make these nanocrystals promising for applications in display, bioanalysis and telecommunications. [source]