Stouwdam, Jan W. C. J. M. van Veggel, Frank Improvement in the Luminescence Properties and Processability of LaF<sub>3</sub>/Ln and LaPO<sub>4</sub>/Ln Nanoparticles by Surface Modification The surface of lanthanide(III)-doped LaPO<sub>4</sub> nanoparticles was modified by reaction with an alcohol, leading to a covalent bond between the ligand and the particle surface. The surface of lanthanide(III)-doped LaF<sub>3</sub> nanoparticles was modified to alter the solubility of the nanoparticles and study the influence of surface effects on the luminescence of lanthanide ions doped in the nanoparticles. The coordinated organic ligands can be modified by a quantitative exchange reaction in solution or by using functionalized ligands during the synthesis. Variation of the ratio of ligand to core reagents had a significant influence on the size of the nanoparticles. Smaller nanoparticles were formed with a higher ligand ratio. The optical properties of these nanoparticles show a strong dependence on nanoparticle size, indicating the influence of quenching probably by CH and OH groups at or near the surface of the nanoparticle cores. The luminescence lifetime of LaF<sub>3</sub>/Eu nanoparticles varied from 6.5 to 7.4 ms for nanoparticles with an average size of 7.1 to 8.4 nm. A significant reduction of the quenching from the surface of the nanoparticles was obtained by the synthesis of core−shell nanoparticles, in which a shell of LaF<sub>3</sub> was grown epitaxially around the doped core nanoparticles. This leads to an increase in the luminescence lifetime of the Eu<sup>3+</sup> ion and the observation of emissions from the <sup>5</sup>D<sub>2</sub> energy level, in addition to emissions from the <sup>5</sup>D<sub>1</sub> and <sup>5</sup>D<sub>0</sub> levels. The quantum yield of LaF<sub>3</sub>/Ce,Tb nanoparticles could be increased from 24 to 54% by the growth of a LaF<sub>3</sub> shell around the nanoparticles. nanoparticle;5 D 1;OH;5 D 2 energy level;LaF 3 shell;5 D 0 levels;surface;CH;luminescence lifetime 2004-12-21
    https://acs.figshare.com/articles/journal_contribution/Improvement_in_the_Luminescence_Properties_and_Processability_of_LaF_sub_3_sub_Ln_and_LaPO_sub_4_sub_Ln_Nanoparticles_by_Surface_Modification/3311464
10.1021/la048379g.s001