Investigating the diameter effect of gold and silver nanoshells with specific outsider diagonal on localized surface pasmon resonance by the FDTD method

In this research, localized surface plasmon resonance spectra for single spherical gold nanoparticles with radius between 20 to 55nm in environments of different refractive indices between 1 and 1.8 has been studied by Finite Different Time Domain method. In this simulations, plasmon resonance frequency is determined for each nanoparticle with optimized mesh size, and is compared with the results of Mie theory. Moreover, using these results, plasmonic propertis of gold nanoshells of various diameters were studied in air (n=1) and water (n=1.33). Plasmon resonance has been calculated for nanoshells and it was concluded that in different environments, gold nanoshells with outer radius of 20 nanometers and diameter of 12 nanometers have their plasmonic spectrum are associated on gold nanosphere with the same outer radius.  frequency for nanoshells has been calculated. The plasmon resonance peak shift for various nanoparticles is plotted versus refractive indices. Finally, the most sensitive and most insennitive of nanoparticles to the refractive index of the environment has been discussed for sensing applications.