Multisignal optical temperature-sensing properties of Eu 3+ -doped NaYF 4 nanoparticles.

In this paper, the multisignal (different emissions/colours) temperature sensing of NaYF :Eu nanoparticles is investigated, which is based on fluorescence intensity ratios (FIRs) between D → F (J=1-4) and D → F emissions. The D → F (J'=0-2) emissions can be clearly observed due to the low photon energy of NaYF . Based on the FIRs between different D → F and D → F emissions, higher absolute/relative temperature sensitivities are obtained. Compared with the FIR between whole D → F and D → F emissions, the maximum value of S was improved from 0.27 K to 5.02 K and that of S was improved from 0.89%·K to 1.27%·K . Furthermore, the FIRs between different colours of emissions were investigated for the application of wide-range multicolour temperature sensing.