Surface plasmon coupling between two nano Au particles

Nano metal particles which interact strongly with visible light make themselves useful for molecular detection and biosensing. To facilitate the useful application for these nano particles, it is important to design and fabricate the particles at a desired frequency. In this paper, we present our experimental and computer simulation studies on the plasmon resonance of single nano Au particles and nano Au particle pairs in close proximity. The results show that the resonant wavelength peak of two particle plasmons is red-shifted in comparison to that of a single particle and the shift decays approximately exponentially with particle spacing, and drops to zero when the gap between two particles exceeds about 2.5 times the particle short axis length. It is also found that the decay function of the resonant wavelength shift is size-independent.