Location-Dependent Local Field Enhancement Along the Surface of the Metal–Dielectric Core–Shell Nanostructure

Abstract

A theoretical study based on quasi-static approximation is performed to investigate the location-dependent local field enhancement around the dielectric shell-coated gold nanosphere. Our calculation results show that the local field distribution near a gold nanoparticle can be altered greatly by coating with a dielectric shell. Because of the polarizability of the dielectric shell, increasing azimuth angle along the inner surface leads to the increase of the local field, which is opposite to that of the outer surface. Furthermore, the location-dependent local field enhancement and resonance frequency at both the inner and outer surfaces can also be modulated by varying the shell thickness and shell dielectric constant. These calculation results about the locationdependent local field enhancement show the potential of dielectric-coated metallic nanostructure for single-molecule detection based on surface-enhanced Raman scattering and surface enhanced fluorescence.

Enhanced multi-phonon Raman scattering and nonlinear optical power limiting in ZnO:Au nanostructures

“…These include analytical methods derived from Mie theory for spheres, quasistatic (Gans) model for spheres and spheroids, and numerical methods like discrete dipole approximation (DDA), nite difference time domain (FDTD) method, and nite element method (FEM). [48][49][50][51][52][53][54][55] Tanabe et al 56 has discussed the dependence of eld enhancement on parameters such as wavelength, distance from the NP/nanoshell, surrounding medium, and the core and shell diameters, based on classical electromagnetic eld theory in the quasistatic limit using empirical wavelength-dependent dielectric constants. When a homogeneous, isotropic metal sphere is placed in a medium under static electric eld ( Ẽ0 ¼ E 0 êz ), it will experience an induced charge on its surface due to the difference in dielectric constants between the metal sphere and the medium.…”

Effects of surface oxidation on the linear optical properties of Cu nanoparticles

“…For instance, they can be used for cancer treatments [7,8], catalysis [9,10], photo-heat conversion [11], surfaceenhanced Raman scattering [12], second harmonic generation [13] and biological or chemical sensing [14]. Moreover, the significant increase in the local electric field produced by the surface plasmon resonance (SPR) [15] is useful for several linear [16] and nonlinear [17][18][19] optical processes. Copper is an important metal because of its high electrical and thermal conductivities [20,21].…”