Local Surface-Plasmons in Nonspherical Metal Nanoparticles

When a small metallic nanoparticle is irradiated by incident light, the oscillating electric field can cause the conduction electrons to oscillate coherently, which excites the local surface plasmons (LSPs). As is well known, excited LSPs can gather the energy of incident light to the surface of metallic nanoparticle. Recently, some nonspherical particles, e.g. tetrahedron, are suggested to obtain stronger localized electric field. We employ the discrete dipole approximation method to calculate the optical response of the tetrahedron nanoparticle, including the extinction and distribution of the electric field around the particle. The influences of some parameters, including the nanoparticle size, incident direction and polarization, are investigated to analyse the response modes and to obtain stronger localized electric field.