Interaction of rare earth ions doped in nanocrystals embedded in amorphous matrices with two-level systems of the matrix

The interactions of rare earth ions doped in nanoparticles with the amorphous matrix in which they are embedded are studied with hole burning and fluorescence line narrowing techniques. The results suggest that at low temperatures the homogeneous broadening of optical transitions of the rare earth ions are dominated by interactions with the two-level systems of amorphous matrix. At higher temperatures other phonon-induced processes which are seen in bulk single crystals dominate the dynamics.