Local dipole field enhancement along the surface of metal-dielectric Au/Pd core-shell nanostructure

The nanostructure of bimetallic Au/Pd particles was fabricated to investigate their surface plasmon (SP) dynamics and local field factor. The SP dynamics was detected according to the structure, electric dipole and multipole electrical quadrupole moment. It was found that the symmetric coupling red shifts decreased obviously with the increase of the shell thickness and the nanoparticle size, and the absorption efficiencies of the nanostructure depended on the SP resonance frequency. The waves of surface plasmon Pd/Au are achieved by gradient of electrons density between interface and shell layer. The dipole couple and electrical quadrupole moment make the plasmonic anisotropy related to transition of electron energy band. The FWHM under collective plasmonic enhancement has been found to enlarge with rise of radius ratio.Moreover, the SP resonance and the local field were measured with annular limited optical distribution in terms of dipole resonance mode and resonance frequency. The resonance scattering has been changed inspite of the Au/Pd deformation and the collective plasmon enhancement. Besides, the single particle in Z direction went up with the particle dimension. The solid structures of the Au/Pd Core/shell nanoparticles were measured by TEM and EDS.