Eu-based luminescence ratiometric thermometry.

Recently, luminescence ratiometric thermometry has gained ever-increasing attention due to its merits of rapid response, non-invasiveness, high spatial resolution, and so forth. For research fields relying on temperature measurements, achieving a higher relative sensitivity of this measurement is still an important task. In this work, we developed a strategy for achieving a more sensitive temperature measurement, one merely depending on the photoluminescence of Eu. We showed that using the D-F transition and the hypersensitive D-F transition of Eu can boost the relative sensitivity compared with the method relying on the D-F and D-F transitions of Eu. The difference between these two strategies was studied and was explained by the hypersensitive D-F transition more steeply decreasing than the D-F transition with a rise in temperature. Our work is expected to help researchers design sensitive optical thermometers proper use of this hypersensitive transition.