Plasmon-Enhanced Upconversion in Single NaYF₄:Yb³⁺/Er³⁺ Codoped Nanocrystals

Abstract

In this Letter we report the plasmon-enhanced upconversion in single NaYF(4) nanocrystals codoped with Yb(3+)/Er(3+). Single nanocrystals and gold nanospheres are investigated and assembled in a combined confocal and atomic force microscope setup. The nanocrystals show strong upconversion emission in the green and red under excitation with a continuous wave laser in the near-infrared at 973 nm. By the use of the atomic force microscope, we couple single nanocrystals with gold spheres (30 and 60 nm in diameter) to obtain enhanced upconversion emission. An overall enhancement factor of 3.8 is reached. A comparison of time-resolved measurements on the bare nanocrystal and the coupled nanocrystal-gold sphere systems unveil that faster excitation as well as faster emission occurs in the nanocrystals.

Influence of metallic nanoparticles on electric-dipole and magnetic-dipole transitions of Eu3+ doped germanate glasses

“…When the distance between the RE and the NP is very small, quenching of PL occurs as demonstrated in experiments that detect the emission from a single atom ͑or molecule͒ located nearby a metallic NP or in the proximity of a metallic film. [12][13][14] In the past years the synthesis and characterization of heavy-metal oxide glasses doped with RE ions and containing metallic NPs were reported for a large variety of glasses. [1][2][3][4][5][6][7][8][15][16][17][18][19][20][21][22][23] Intensification of Stokes and anti-Stokes luminescence due to nucleation of silver or gold NPs was investigated in tellurite and germanate glasses doped with RE ions under various excitation conditions.…”

Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers

“…17,18 Single UCNP emission has been reported by different groups that managed to achieve the upconverting emission spectrum of individual Er/Yb copdoped UCNPs. [19][20][21][22] In these cases particle immobilization was achieved by drop casting a diluted suspension of UCNPs on a solid substrate, in such a way those UCNPs under study were in an open air environment. These pioneering investigations pointed out the potential use of UCNPs as single-particle imaging probes due to the large signal-to noise ratio obtained in the single particle emission spectrum.…”

Recent advances in the optimization and functionalization of upconversion nanomaterials for in vivo bioapplications

“…In addition, a series of similar upconversion nanocomposites with noble metals has been fabricated to enhance the upconversion emissions. [45][46][47][48][49] Unfortunately, most of this work focuses on observing the enhancement effects rather than describing the detailed mechanism behind them. Therefore, there is no confirmed information available to direct the design of such nanocomposites to further improve the upconversion emissions until now.…”