The use of energy looping between Tm³⁺ and Er³⁺ ions to obtain an intense upconversion under the 1208 nm radiation and its use in temperature sensing

Abstract

Core@shell nanoparticles doped with Tm3+ and Er3+ ions exhibit intense temperature-dependent photon upconversion when subjected to 1208 nm laser excitation. The mechanism behind this observed emission is elucidated, unveiling its intricate nature.

Lanthanide-based nanomaterials for temperature sensing in the near-infrared spectral region: illuminating progress and challenges

“…In fact, there are a few successful examples that demonstrate the thermal sensing capability of Tm 3+ -doped NPs for NIR-NIR nanothermometry under aforementioned longer excitation. 24,25,59,60 Herein, under 1210 nm excitation, a higher maximum S r was achieved compared to 1319 nm excitation (2.64% K −1 versus 0.80% K −1 ). 24,25 While taking advantage of the longer excitation wavelengths, the upconverted NIR-I emission bands associated with the Tm 3+ 3 F 2,3 → 3 H 6 and 3 H 4 → 3 H 6 transitions (centred at 700 and 800 nm, respectively), were used to determine the thermometric parameters based on a LIR approach.…”

“…1C). 23–25,59,60 The benefits of 808 nm as excitation source have been outlined above, however, compared to Nd 3+ , the absorption cross section of Tm 3+ at 808 nm is relatively low. 38 Consequently, Tm 3+ -sensitized NIR emissions often suffer from low signal-to-noise ratios, which hampers thermometric performance.…”