Visible Discrimination of Broadband Infrared Light by Dye-Enhanced Upconversion in Lanthanide-Doped Nanocrystals

Figure 7

Demonstration of dye-induced upconversion of NaYF₄ nanoparticles doped with Yb³⁺ sensitizer and holmium activator (NaY_0.78Yb_0.20Ho_0.02F₄). Plots (a), (b), and (c) show the emission for excitation at 801 nm, 819 nm, and 832 nm, respectively, where the attached DY-831 infrared dye absorbs, but where the Yb³⁺ sensitizer does not. Characteristic Ho³⁺ upconversion is seen in plot (d) for excitation at 975 nm. Ho³⁺ upconversion is seen in plots (a), (b), and (c) for the dye-attached nanoparticles (black curves), while none is seen for the control nanoparticles without attached dye (blue curves).