Creating Hot Nanoparticle Pairs for Surface-Enhanced Raman Spectroscopy through Optical Manipulation

Abstract

We use optical tweezers to move single silver nanoparticles into near-field contact with immobilized particles, forming isolated surface-enhanced Raman spectroscopy (SERS) active Ag particle dimers. The surface-averaged SERS intensity increases by a factor approximately 20 upon dimerization. Electrodynamics calculations indicate that the final approach between the particles is due to "optical binding". The described methodology may facilitate controlled single molecule SERS analysis.