Optimization of silver-dielectric-silver nanoshell for sensing applications

Abstract

In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

Geometrical Parameter Effect on Plasmonic Scattering of Bimetallic Three-Layered Nanoshells

“…Figure 6 a shows that the scattering efficiency of silver–dielectric–gold nanoshell increases by increasing the surrounding medium function from to , where becomes intense quickly and increases slowly, unlike that of Figure 5 . The inset of scattering cross section is shown in Figure 6 a, where causes a distinct red-shift with increasing surrounding medium function [ 15 , 19 ]. Due to the dielectric screening with a high refractive index, the induced charge on the outer gold nanoshell surface decreases, and then the induced charge on the inner surface of the silver core follows.…”

“…Figure 7 b shows the local electric field focused in the middle dielectric layer, whereas the inner gold core and outer silver nanoshell are much weaker at wavelength 722 nm. There are different kinds of charges signed on the inner gold core and inner surface of the outer silver nanoshell, which attracts in mode [ 15 , 19 ]. The scattering efficiency can be well improved with the larger inner core radius , smaller middle dielectric layer function , and larger surrounding medium .…”

“…The result has demonstrated that the intensity and position of the scattering peaks depend on shell thicknesses [ 17 ]. Shirzaditabar et al have studied geometrical parameters’ effect on the local electric field of silver–dielectric–silver multi-layer nanoshell; it is found that the resonance wavelength exhibits a red-shift by increasing the silver core radius [ 18 , 19 ]. Campbell and Ziolkowski have designed concentric double-negative metamaterial spheres.…”

Triple plasmon resonance of bimetal nanoshell

“…Our previous studies demonstrated that silver-dielectric-silver (SDS) nanoshell has three LSPR peaks in its scattering spectra and could be optimized for biomedical sensing. 10,11 However, the shortest wavelength peak is also very weak. If this peak could be enhanced, there will be three intense and separate LSPR peaks for multiplex sensing.…”

Optical absorption tunability and local electric field distribution of gold-dielectric-silver three-layered cylindrical nanotube*

“…[12] Schiditabar et al have investigated the resonance light scattering properties of silver-dielectricsilver nanoshell based on quasi-static approach, and the results show that LSPR are optimized by tuning the geometrical dimensions. [13] Based on the light absorption spectra properties of a bimetallic multilayer nanoshell (silver-dielectricsilver, gold-dielectric-silver and silver-dielectric-gold), the results show that relatively small thickness of outer silver shell and large dielectric constants of middle dielectric layer of gold-dielectric-silver nanoshell are suitable to obtain the triple plasmon resonance. [14] Recently, the optical properties of nanotube have also been widely investigated and applied in biological tissues, nanosensors, optical devices, optical data storage and some regions.…”