Ultrafast electron relaxation via breathing vibration of gold nanocrystalsembedded in a dielectric medium - art. no. 104302

Relaxation dynamics of electrons in gold nanocrystals with diameters of 3.0 -17.5 nm embedded in SiO2, Al2O3, and TiO2 matrices have been investigated by means of femtosecond pump and probe spectroscopy. The experiments show t hat the energy relaxation rates depend on both the nanocrystal size and the matrix material. A model taking account of electron-breathing mode interac tion, electron-bulk phonon interaction, and thermal diffusion through the i nterface can explain well the observed results, The breathing mode damping in the medium on a time scale of a few picoseconds plays an important role in the electron-energy dissipation process of the nanoscale composite syste m.