Plamonic behavior of metallic and core-shell nanostructures

Nanoscale interaction between the metal and semiconductor in core shell nanoparticles (NPs) when light is incident to this nanostructure, causes exhibiting reinforced optical responses and enhanced optical tunability in core shell NPs. In this work, we investigate the geometry and electronic properties dependent optical properties of Au-SiO₂ core shell NPs and Au NPs using boundary element method (BEM) by solving full Maxwell´s equation. We find out that several important geometrical parameters such as shell thickness, core diameter, electronic properties of shell and surrounding environment affect the plasmon resonance wavelength, light scattering, absorption and extinction cross section of core shell NPs. We also investigate the effect of variation in size and surrounding refractive index on Au NPs. Surrounding refractive index dependence of Au NPs makes them suitable for plasmonic based sensors. We validate our BEM approach for spherical NPs with Mie theory.