By combination of two special methods, i.e., persistent spectral hole burning and laser assisted nanoparticle preparation, the dephasing time $T_2$ of surface plasmon excitation in silver nanoparticles was systematically investigated. A strong dependence of $T_2$ on the plasmon energy is found which reflects the relevance of interband damping and makes necessary a precise control of the particle shape when measuring $T_2$. The influence of the reduced dimension on the dephasing dynamics was observed as a decrease of $T_2$ with shrinking particle size. In addition, for silver nanoparticles on quartz substrates, a considerable amount of chemical interface damping was observed.

• Received 21 August 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.257404