Chapter 5:Luminescent Nanothermometry with Lanthanide-doped Nanoparticles

The remarkable optical properties of the trivalent lanthanide ions including their characteristically narrow emission bands, size-independent emission and their capacity to (up)convert near-infrared (NIR) radiation to higher energies spanning the UV–NIR range of the spectrum renders them ideal for biological applications and especially for temperature measurements both in vitro and in vivo. In this chapter, we discuss the fundamental luminescent properties of lanthanide-doped nanoparticles with a special emphasis on temperature-sensitive emissions and their applications in nanothermometry, encompassing ratiometric approaches related to the variation of the relative peak intensities of two transitions or Stark levels of a dopant ion, as well as the temperature-dependent lifetimes of the emitting states.