Polarization-selective imaging of the enhanced local field at gold nanoparticle junctions

Abstract

The electromagnetic gap-mode is believed to be the major cause of the colossal surface-enhanced Raman scattering (SERS) signals recently discovered. However, no direct spatial correlation among the local field and the morphology has been established thus far. Here, we demonstrate that scattering-type apertureless near-field scanning optical microscopy (ANSOM) can visualize the gap-mode formed between gold nanoparticles with a spatial resolution better than 10 nm.