Importance of Volume Ratio in Photonic Effects of Lanthanide-Doped LaPO Nanocrystals.

Experimental variation of the volume ratio (filling factor: i.e., volume of nanoparticles (NPs) compared with that of medium) of nanocomposite materials with doped lanthanide ions demonstrates that it has a significant affect upon local field effects.

Energy Transfer between Tb and Eu in LaPO: Pulsed versus Switched-off Continuous Wave Excitation.

The energy transfer (ET) between Tb and Eu is investigated experimentally and with available theoretical models in the regime of high Tb concentrations in ≈30 nm LaPO nanoparticles at room temperature. The ET efficiency approaches 100% even for lightly Eu-doped materials. The major conclusion from the use of pulsed laser excitation and switched-off continuous wave laser diode excitation is that the energy migration between Tb ions, situated on La sites with ≈4 Å separation, is not fast.

In vitro cell imaging using multifunctional small sized KGdF4:Yb3+,Er3+ upconverting nanoparticles synthesized by a one-pot solvothermal process.

Multifunctional KGdF4:18%Yb(3+),2%Er(3+) nanoparticles with upconversion fluorescence and paramagnetism are synthesized. The average sizes of the nanoparticles capped with branched polyethyleneimine (PEI) and 6-aminocaproic acid (6AA) are ~14 and ~13 nm, respectively. Our KGdF4 host does not exhibit any phase change with the decrease of particle size, which can prevent the detrimental significant decrease in upconversion luminescence caused by this effect observed in the well-known NaYF4 host.

Towards pure near-infrared to near-infrared upconversion of multifunctional GdF(3):Yb(3+),Tm(3+) nanoparticles.

Nearly pure near-infrared to near-infrared (NIR-to-NIR) upconversion in GdF(3) host with 23% Yb(3+) and 1% Tm(3+) under 980 nm excitation is firstly reported. The ratio of the intensity of the emission at 807 nm to that at 478 nm can reach to 105, and the intensity of the emission at 807 nm is preserved. Moreover, the excitation and the emission at 980 and 807 nm are away from the visible region.