Plasmonic Coupling Dynamics of Silver Nanoparticles in an Optical Trap

We investigate binding and plasmonic coupling between optically trapped 80 nm silver spheres using a combination of spectroscopic sensing and 3D interferometric laser particle tracking on a 1 μs time scale. We demonstrate that nanoparticle coupling can be either spontaneous or induced by another particle through confinement of diffusion. We reveal ultrafast entries and exits of nanoparticles inside the optical trap, fast particle rearrangements before binding, and dimer formation allowing new insights into nanoparticle self-assembly.