Spectra Analysis of Nd$lt;sup$gt;3+$lt;/sup$gt; Sensitized NaYF$lt;inf$gt;4$lt;/inf$gt;:Yb@NaYF$lt;inf$gt;4$lt;/inf$gt;:Ho Upconversion Nanoparticles

Upconversion nanoparticles are widely used in bioimaging and biomarkers because of their excellent penetration depth and strong luminescence.Mono dispersed core-shell structured NaYF 4 :Yb@NaYF 4 :Ho nanoparticles with sizes of about 50 nm were synthesized.It was found by spectral analysis that these nanoparticles emitted light centered at a wavelength of 650 nm under the 980 nm laser excitation.Further Nd 3+ doping caused the NaYF 4 :Yb@NaYF 4 :Ho nanoparticles to emit strong red light under the 800 nm laser excitation.By analyzing the fluorescence spectra of the Nd 3+ doped NaYF 4 :Yb@NaYF 4 :Ho nanoparticles with different structures, it was found that the emission intensity of the NaYF 4 :Yb@NaYF 4 :Ho, Nd nanoparticles was the strongest, indicating that doping Nd 3+ ions into the shell layer of the NaYF 4 :Yb@NaYF 4 :Ho nanoparticles was optimal choice.Finally, the Nd 3+ concentration of the NaYF 4 :Yb 3+ 50%@NaYF 4 :Ho 3+ 1%, Nd 3+ x% nanoparticles was optimized.The experimental results show that the optimized concentration of Nd 3+ ions is 30%, the luminescence intensity of the NaYF 4 : Yb 3+ 50%@NaYF 4 :Ho 3+ 1%,Nd 3+ 30% nanoparticles is strongest under an 800 nm laser excitation.