Ultrafast studies on the energy relaxation dynamics and the concentration dependence in Ag:Bi2O3 nanocomposite films

The energy relaxation dynamics in Ag:Bi2O3 nanocomposite films with high density of Ag nanoparticles were investigated by femtosecond pump-probe technique. For the films with relatively low Ag concentration (13.2-35.7 at.%), the energy relaxation is nearly completed within 1 picosecond (ps) at moderate excitation regime. For the film with 52.0 at.% Ag concentration, the relaxation process consists of a fast power-dependent component (1-2 ps) and a long-lived one. The different relaxation characteristics are suggested to be resulted from the differences in the structural and thermal properties of the surrounding Bi2O3 matrix coupling with Ag nanoparticles.