Plasmon resonances of spherical and ellipsoidal nanoparticles

Surface plasmon resonance (SPR) of a single metallic nanoparticle is analyzed and simulated via multi-multipole method for 3D problems. The excitation, at optical frequencies, of the SPR leads to an extremely strong field in the vicinity of the nanoparticle. Numerical results indicate that a red shift of SPR is induced for an ellipsoidal nanoparticle, compared to a spherical one. Two structures of core-shelled spherical nanoparticles are also studied; one is a nanosphere of Ag shell with an oxide core, and the other one is Ag core with an oxide shell (ZrO2 Or SiO2). Numerical results illustrate the SPR of these two core-shelled structures are quite different from each other and different from that of a solid one. It suggests that one can manipulate the optical response on demand by tuning the core/shell ratio and the permittivity of shell or core.