Coherent acoustic mode oscillation and damping in silver nanoparticles

Using a femtosecond pump-probe technique, the fundamental mechanical radial mode of silver nanoparticles is coherently excited and probed via its inte raction with the electron gas. The mechanical oscillations are launched by an indirect displacive process and are detected via the induced modulation of the surface plasmon resonance frequency. The measured fundamental radial mode period and damping time are found to be proportional to the nanoparti cle radius in the range of 3-15 nm, in agreement with theoretical predictio ns. (C) 1999 American Institute of Physics. [S0021-9606(99)70223-0].