Two Photon Thermal Sensing in Er<SUP>3+</SUP>/Yb<SUP>3+</SUP> Co-Doped Nanocrystalline NaNbO<SUB>3</SUB>

Abstract

We investigate the potential use of two-photon absorption of Er3+/Yb3+ co-doped NaNbO3 nanocrystals for nanothermometry as well as thermal imaging, based on the thermally coupled green Er3+ emission lines. In fact, thermal sensor in the range of 20-80 degrees C with -0.1 degrees C accuracy using excitation powers readily obtained from commercially available semiconductor laser was achieved. The pump-intensity induced local heating was also investigated upon femtosecond laser excitation and 0.55 K/kW x cm(-2) was achieved. The highly efficient green emission together with two-photon dependence and femtosecond laser excitation should increase the brightness of thermal imaging. Additionally, the high temperature-sensitive fluorescence, when compared to previous literatures, should increase the resolution of nanothermometers.

Ultrasmall, water dispersible, TWEEN80 modified Yb:Er:NaGd(WO4)2nanoparticles with record upconversion ratiometric thermal sensitivity and their internalization by mesenchymal stem cells

“…For comparison, S MAX values and corresponding temperatures of different materials previously published are reported in the SI (see table SI.1). Accordingly to these results and to a recent description of the state of art of UC thermometry [41], the presently reported ratiometric thermal sensitivities for tetragonal Yb:Er:NaTX compounds are the largest obtained in any Yb:Er codoped host.…”

Efficient up-conversion in Yb:Er:NaT(XO4)2 thermal nanoprobes. Imaging of their distribution in a perfused mouse

“…Despite the prevalence of Yb:Er:β-NaYF 4 as UC media, the search of alternative UC materials is continuously pursuit due to the following reasons: i) The synthesis of β-NaYF 4 hexagonal gagarinite phase ( space group) competes with the nucleation of the substantially less efficient α-NaYF 4 cubic phase ( space group); ii) preparative routes for fluorides are often environmental harmful; iii) the UC ratiometric thermal sensitivity ( S ) of Yb:Er:β-NaYF 4 is weak, in comparison to other studied materials; [24] and iv) the UC efficiency of Yb:Er:β-NaYF 4 is reduced by three orders of magnitude on going from bulk to ultrasmall NPs with ≈10 nm size. [25]…”