In this contribution, we present measurements of the ultrafast dephasing time T₂ of surface plasmon polariton excitation in gold nanoparticles by means of persistent spectral hole burning. T₂ is an essential parameter that does not only reflect the role of different dephasing and deexcitation mechanisms but also allows one to determine the field enhancement factor that is of great importance for many applications of nanoparticles. In our experiments gold nanoparticles were first fabricated in ultrahigh vacuum on sapphire substrates by deposition of atoms, followed by diffusion and nucleation, i.e. Volmer-Weber growth. Subsequently, systematic measurements of T₂ in the size range between r = 7 nm and 14 nm were carried out. The most essential among the numerous results is the observation of the influence of the reduced dimension on the dephasing time. While T₂ = 14 fs has been measured for r = 12 nm which is, within the error bars, consistent with the damping contained in the bulk dielectric function, the value of T₂ shrinks to, for example, T₂ = 11 fs for r = 7 nm. This reduction of T₂ can be attributed to surface scattering of the electrons. Further experiments are in progress to confirm the predicted 1/r law for the variation of T₂.

Date Published: 28 October 2003
PDF: 12 pages
Proc. SPIE 5221, Plasmonics: Metallic Nanostructures and Their Optical Properties, (28 October 2003); doi: 10.1117/12.503662

Published in SPIE Proceedings Vol. 5221:
Plasmonics: Metallic Nanostructures and Their Optical Properties
Naomi J. Halas, Editor(s)