Constructing highly sensitive ratiometric nanothermometers based on indirectly thermally coupled levels

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Ratiometric temperature sensing requires self-referencing for accuracy.
• Lanthanide ions are used for sensing but have limitations like low sensitivity.
• Existing methods struggle with luminescence signal discrimination.

Purpose of the Study:

• To introduce and apply the concept of indirectly thermally coupled levels for high-performance temperature sensing.
• To develop a novel nanothermometer for accurate and reliable temperature measurements.
• To overcome limitations of traditional lanthanide-based ratiometric sensors.

Main Methods:

• Utilizing temperature-dependent phonon-assisted non-radiative relaxation.
• Indirectly thermally coupling the 4I13/2 (infrared emission) and 4S3/2 (visible emission) excited states of Erbium ions (Er3+).
• Synthesizing and characterizing NaErF4:10Yb@NaYF4 nanocrystals for sensing applications.

Main Results:

• Demonstrated indirect thermal coupling between Er3+ excited states via phonon-assisted relaxation.
• Achieved excellent luminescence thermal sensing performance in NaErF4:10Yb@NaYF4 nanocrystals.
• Obtained a maximum relative temperature sensitivity of 3.76% K-1 at 295 K.

Conclusions:

• The concept of indirectly thermally coupled levels enables high-performance ratiometric temperature sensing.
• The developed NaErF4:10Yb@NaYF4 nanothermometer offers a promising solution for accurate and sensitive temperature measurements.
• This approach overcomes key limitations of existing lanthanide-based ratiometric sensing systems.