NDLI: Europium-doped $LaF_{3}$ nanocrystals with organic 9-oxidophenalenone capping ligands that display visible light excitable steady-state blue and time-delayed red emission

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Sharma, Dharmendar Kumar Chowdhury, Arindam Irfanullah, Mir Chulliyil, Ramya
Description	Author Affiliation: Irfanullah M ( Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India. mir.irfanullah@gmail.com mirfanullah@chem.iitb.ac.in arindam@chem.iitb.ac.in.)
Abstract	Visible light excitable and color tunable ∼5% $Eu^{3+}-doped$ $LaF_{3}$ nanocrystals (NCs), containing 9-oxidophenalenone ligands bound to the surface as visible light sensitizers for $Eu^{3+}$ dopants, have been synthesized by a facile solution-based method. The crystalline phase structure, size, composition, morphology and luminescence properties of the NCs are characterized using X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and steady-state and time-resolved emission spectroscopy. The results show that these NCs are very small in size (<10 nm), display high degree of crystallinity and have pure tysonite structure of $LaF_{3}$ with Pc1 space group. The visible light excitation of the capping ligands triggers an alternate display of steady-state, short-lived blue emission (τ < 1 ns) and time-delayed, long-lived sensitized red $Eu^{3+}$ emission (τ = 0.41 ms), allowing photoluminescence chromacity tuning as a function of delay time within a specific inorganic composition. The visible light sensitization of the dopant $Eu^{3+}$ sites proves more efficient than direct excitation of 5% $Eu^{3+}-doped$ $LaF_{3}$ NCs capped by citrate ligands. The dopant $Eu^{3+}$ ions are well protected from non-radiative deactivation through high-energy vibrations of the organic capping ligands which is proved by the long lifetime of the sensitized $Eu^{3+}$ emission. The time-resolved emission spectra collected over a period of several milliseconds reveal that the dopant $Eu^{3+}$ ions occupy at least three different sites in the NC host. It is further inferred that the sensitized $Eu^{3+}$ emission primarily comes from surface dopant sites and sites just underneath the surface of the NCs. We propose that some of the interior $Eu^{3+}$ sites also display sensitized emission, which are indirectly populated via $Eu^{3+}$ → $Eu^{3+}$ energy migration from surface-sensitized $Eu^{3+}$ sites of the NCs.
ISSN	14779226
Issue Number	7
Volume Number	44
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-02-21
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Europium Chemistry Fluorides Lanthanum Light Luminescence Nanoparticles Phenalenes Ligands Time Factors X-Ray Diffraction Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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