Theoretical Studies of Tunable Localized Surface Plasmon Resonance of Gold-Dielectric Multilayered Nanoshells

Abstract

Tunable properties of localized surface plasmon resonances (LSPR) of gold-dielectric multilayered nanoshells are studied by quasi-static theory and plasmon hybridization theory. Multilayered nanoshells with the gold core and nanoshell separated by a spacer layer exhibit strong coupling between the core and nanoshell plasmon resonance modes. It is found that the absorption spectra characteristics of LSPR are sensitive to multiple parameters including the surrounding medium refractive index, the dielectric constant of spacer layer, the radius of inner core gold sphere, outer shell layer thickness, and their coupling strength. The results show that LSPR is mainly influenced by the ratio of spacer layer dielectric constant e 2 to surrounding medium dielectric constant e 4. Absorption spectrum of $\left |\omega _{-}^{+}\right \rangle $ mode is red-shifted with increasing core radius when e 2 > e 4. It is surprising to find that LSPR is blue-shifted with increasing core radius when e 2 < e 4, and no shift when e 2 = e 4. These interesting contrary shifts of $\left |\omega _{-}^{+}\right \rangle $ mode with different ratios e 2/e 4 are well analysed with plasmon hybridization theory and the distributions of induced charges interaction between the inner core and outer shell. In addition, for the sake of clarity, the distributions of electric filed intensity at their plasmon resonance wavelengths are also calculated. This work may provide an alternative approach to analyse property of the core-shell nanoshell particles based on plasmon hybridization theory and the induced charge interaction.