Electrodynamics study of plasmonic bonding and antibonding forces in a bisphere

Light excitation of surface plasmons in metallic nanoparticle clusters can induce huge forces. We study such forces by using an electrodynamics approach, which fully incorporates the retardation effect. As two particles approach each other, the single-particle plasmons hybridize and split into attractive bonding modes and repulsive antibonding modes, which eventually evolve into an attractive band and a repulsive band. At an intensity of about 0.05 W/mu m(2), the force can reach nano-Newtons and, hence, can dominate over other relevant interactions.