The location and identity of molecules on the surface of plasmonic nanostructures is critical for defining the interaction between the two materials, which is important for any spectroscopic or sensing application utilizing hybrid organic-plasmonic systems. Unfortunately, the size of both organic molecules and many plasmonic nanostructures of interest are well below the wavelength of light, which means that the coupled molecule-plasmon system will appear as a diffraction-limited spot when imaged by far-field optical microscopy. As a result, probing where molecules are located with respect to the nanostructure remains a distinct experimental challenge. This talk will describe how super-resolution optical imaging can yield insight into the coupling between molecules and plasmonic nanostructures, both with respect to where the molecules are bound to the nanostructure surface as well as how the position of the molecules impacts its radiative coupling to the plasmon modes of the nanostructure.
The Willets lab is interested in understanding how heterogeneity at the nanoscale impacts materials properties and functions, with applications in spectroscopy, molecular sensing, and electrochemistry. Our primary focus is in the field of plasmonics, in which we study the interactions among ~10-100 nm noble metal nanostructures, organic molecules, and light. We use a variety of spectroscopy and microscopy techniques, including super-resolution imaging, single molecule fluorescence, surface-enhanced Raman scattering (SERS), and dark field scattering, and complement these studies with structural characterization methods such as atomic force microscopy and electron microscopy.