Super-resolution optical imaging of single molecules probing multiple SERS hot spots

We track the interaction of single molecules and nanoparticle hot spots by taking single-molecule surface-enhanced Raman scattering (SM-SERS) intensity point-spread images in parallel with SERS spectral data. Using a bi-analyte approach and point spread function (PSF) fitting, we resolve multiple hot spots in a single diffraction limited spot and identify analyte exchange in a single hot spot. We are able to map the position of the multiple SERS centroid mean positions in relation to the centroid associated with nanoparticle photoluminescence offering further evidence of the presence of multiple hot spots.