Electric Field Enhancement by Gold Nano-Sphere and Its Clusters

The confinement of electrons in gold nanoparticles results in Surface Plasmon Resonance (SPR), which is characterized by electric field enhancement in the vicinity of these nanoparticles. This property has been extensively studied and applied in various fields. In our research, we conduct a detailed investigation of plasmonic coupling in spherical gold nanoparticles. Specifically, we use the Discrete Dipole Approximation (DDA) method implemented in DDSCAT to simulate the coupling of electric fields in a doublet of nanoparticles as a function of the distance between them. Our simulations show that the coupling of SPR between two nanoparticles occurs up to a separation of 12 nm. Moreover, we extend our simulations to study the coupling of nanoparticles in linear chains consisting of up to five nanoparticles and in clustered forms. Our results indicate that the SPR coupling in a linear chain occurs, and as the number of nanoparticles increases, the field enhancement also increases. However, we observe that this effect saturates after four nanoparticles in a line. Our study provides insights into the plasmonic coupling in gold nanoparticles, which can aid in the design and optimization of plasmonic devices for various applications.