Optomechanical motions of gold dimer's spin, rotation and revolution manipulated by bessel beam.

The optomechanical motion of a gold nanoparticle (GNP) dimer-a pair of optically bound GNPs-in fluid, manipulated by a Bessel beam, is theoretically studied using the multiple multipole (MMP) method. Since a Bessel beam possesses orbital angular momentum (OAM) and spin angular momentum (SAM) simultaneously, complicated rigid-body motions of the dimer can be induced. The mechanism involves the equilibrium between the optical force with the reactive drag force exerted by the fluid.