Optical Transient Relaxation of an Ag-BaO Composite Thin Film with Supercontinuum Probe

The optical transient absorption spectra of an Ag-BaO thin film have been detected at a wavelength ranging from 400 nm to 1000 nm using the pump supercontinuum probe technique with resolution of 130 fs. We have observed the optical ultrafast relaxation, in which the electrons near the Fermi level of Ag nanoparticles were excited to a non-equilibrium state and then returned to an equilibrium state. The decay time was exponentially fitted and varied from 0.67 ps to 4 ps for different components of the supercontinuum probe. The peak of an unoccupied state for silver at level X'₄ was estimated to be 1.47 eV above the Fermi level.