Sensitized luminescence of LaF3:Eu3+ nanoparticles through pyromellitic acid.

The LaF3 nanoparticles doped with different concentration Eu3+ ions are prepared by a simple and low temperature synthetic route. The nanoparticles with the size of about 3.5 nm are roughly spherical and monodisperse. The emission of Eu3+ ions is sensitized through pyromellitic acid bonded onto the surface of nanoparticles. The structure, morphology, photoluminescence properties and fluorescence dynamics are studied systemically. The results show that the sensitized nanoparticles have a broad absorption band in the UV domain and high asymmetry radio, and enhanced Eu3+ luminescence by "antenna effect" of ligands. The excited state lifetimes of sensitized nanoparticles are longer than those of un-sensitized nanoparticles and corresponding europium complexes.