Boltzmann luminescent nanothermometry: mechanistic criteria and predictive design of thermally coupled levels

Abstract Boltzmann-type luminescent nanothermometry using thermally coupled levels (TCLs) of lanthanide ions is promising for applications in nanotechnology, biomedicine, and aerospace. However, the fundamental rules governing TCLs formation and the reliable prediction of relative sensitivity ( S r ) in specific hosts remain unclear. Here, we develop a population-dynamics framework that quantitatively defines the onset temperature and the thermal coupling window for Boltzmann behavior, dictated by nonradiative rates and the thermalization energy gap (Δ E ). Mechanistic analysis reveals how adjacent levels disturb the balance between thermal population and multi-phonon relaxation, and establishes a practical…

• NN
  National Natural Science Foundation of China

  Awards: 12204425, 12374374
• CP
  China Postdoctoral Science Foundation

  Awards: 2024T170819, 2023M743221
• PG
  People's Government of Jilin Province

  Award: 20230201060GX
• JU
  Jilin University