Plasmon resonances of silver nanowires with a nonregular cross section


Journal Article

We investigate numerically the spectrum of plasmon resonances for metallic nanowires with a nonregular Z, cross section, in the 20-50 nm range. We first consider the resonance spectra corresponding to nanowires whose cross sections form different simplexes. The number of resonances strongly increases when the section symmetry decreases: A cylindrical wire exhibits one resonance, whereas we observe more than five distinct resonances for a triangular particle. The spectral range covered by these different resonances becomes very large, giving to the particle- specific distinct colors. At the resonance, dramatic field enhancement is observed at the vicinity of nonregular particles, where the field amplitude can reach several hundred times that of the illumination field. This near-field enhancement corresponds to surface-enhanced Raman scattering (SERS) enhancement locally in excess of 1012. The distance dependence of this enhancement is investigated and we show that it depends on the plasmon resonance excited in the particle, i.e., on the illumination wavelength. The average Raman enhancement for molecules distributed on the entire particle surface is also computed and discussed in the context of experiments in which large numbers of molecules are used.

Full Text

Duke Authors

Cited Authors

  • Kottmann, J; Martin, OJ; Smith, DR; Schultz, S

Published Date

  • December 15, 2001

Published In

Volume / Issue

  • 64 / 23

Start / End Page

  • 2354021 - 23540210

International Standard Serial Number (ISSN)

  • 0163-1829

Digital Object Identifier (DOI)

  • 10.1103/physrevb.64.235402

Citation Source

  • Scopus