Photo excitation at a certain wavelength in the near infrared (NIR)
followed by luminescence at a shorter wavelength in the visible
(VIS) is called NIR to VIS photon up-conversion fluorescence. This
is a rather unusual process since low energy photons are “converted”
to higher energy photons. At least two lower energy photons are
needed to generate a higher energy photon. Bulk LaF3:Yb,Er;
LaF3:Yb,Ho and LaF3:Yb,Tm are such kind of materials with good
fluorescent efficiency. Such materials can be developed into
fluorescent bio-labels for sensitive bio-imaging, just like CdSe
quantum dots. However, as a labelling material for bio-molecules,
nano-sized particles with mono-dispersed size distribution, high
luminescence efficiency and easily water-dispersible is required. In
this project, we will synthesis of LaF3:Yb,Er; LaF3:Yb,Ho and
LaF3:Yb,Tm nanoparticles, and study their up-conversion properties.
The ultimate goal of this project is to develop a very sensitive
fluorescent label with low detection background.