SERS Orientational Imaging of Silver Nanoparticle Dimers

This Article introduces surface-enhanced Raman scattering (SERS) orientational imaging as a powerful far-field optical technique for determining the in-plane and out-of-plane orientations of SERS-active nanoparticle dimers. Optical images of Rhodamine 6G (R6G) SERS emission patterns are measured and correlated with atomic force microscopy (AFM) images of the associated SERS-active silver nanoparticle dimers. The AFM is used to measure individual silver nanoparticle dimer orientations and height asymmetry, defining in-plane and out-of-plane angles associated with the dimer geometry. Theoretical emission pattern images based on these angles are generated using a simple dipole emission model and show excellent agreement with the experimental emission patterns. This technique provides a rapid all-optical technique to analyze the orientation of SERS active nanoparticle dimers.