Surface plasmon coupling in end-to-end linked gold nanorod dimers and trimers

Abstract

Colloidal gold nanorods were aligned end-to-end via dithiol coupling. The scattering properties of the resultant nanostructures were investigated at the single particle level by combining dark-field microscopy and high resolution scanning electron microscopy. The longitudinal surface plasmon resonance of end-to-end coupled Au nanorods exhibited a red-shift as the number of rods in the chain increased. The nanostructures exhibited polarization-dependent optical properties, due to selective excitation of collective bonding and anti-bonding modes. The surface plasmon peak energy was not strongly dependent on the angle of rod–sphere–rod trimers. The experimental scattering spectra were compared with the results obtained from theoretical calculations using the Finite Element Method (FEM) and found to be in good agreement.