Picosecond characteristics on transient absorption spectra of silver nanoparticles

Transient absorption spectroscopy with femtosecond time resolution of colloidal silver nanoparticles with diameters of 10-100 nm was accomplished. The experimental study was performed by 400 nm pump-broadband probe apparatus in spectral area of 450-600 nm at 1 mJ/cm² excitation intensity level. The obtained picosecond relaxation times depend on particle size. The revealed electron dynamics has the main responsibility for linear absorption during the excitation process. The effect of excitation intensity remained unambiguous. The extracted relaxation times suggest the dominancy of the electron-phonon scattering during the absorption recovery and its spectral dependence. Additional role of electron-electron scattering requires further more advanced study.