Nano-Optical Investigation of Enhanced Field at Gold Nanosphere-Gold Plane Junctions

摘要

The local field distribution around gold nanosphere-gold plane junction has been studied using the finite-difference time-domain (FDTD) electrodynamics calculation procedure.We find that both the in-plane and out-of-plane polarized excitation produce enhanced field strong enough to explain the observed SERS activities of the junctions.Comparison with a simple dipole-image dipole model shows that the enhanced field primarily originates from the multipole-image multipole interaction,which indicates that the detailed fine-structures of the nanoparticles also play a significant role in the SERS activities as well.