Interparticle coupling effects on plasmon resonances of nanogold particles

The collaborative oscillation of conductive electrons in metal nanoparticles results in a surface plasmon resonance that makes them useful for various applications including biolabeling. We investigate the coupling between pairs of elliptical metal particles by simulations and experiments. The results demonstrate that the resonant wavelength peak of two interacting particles is red-shifted from that of a single particle because of near-field coupling. It is also found that the shift decays approximately exponentially with increasing particle spacing and become negligible when the gap between the two particles exceeds about 2.5 times the particle short-axis length.