Project Abstract:

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.