Influence of the cross section and the permittivity on the plasmon-resonance spectrum of silver nanowires

We investigate the plasmon resonances for silver nanowires with a non-regular cross section. To study the relationship between the cross section and the spectrum of the plasmon resonances, we consider cross sections evolving from a rectangular shape to a triangular one. In particular, we study the influence of the sharpness of a corner on the near-field enhancement at the vicinity of a particle and discuss its implications for surface-enhanced Raman scattering. We also investigate the influence of the absorption on the plasmon-resonance spectrum and on the near-field enhancement.