Super-Resolution Near-Field Microscopy and Spectroscopy: Development and Application

December 12, 2014

Terefe Habteyes

Understanding optical and chemical properties of materials at the molecular and nanoscale level is critical for multitude of applications including solar energy harvesting, photocatalysis and sensing as well as for discovery of emergent material functionalities. Near-field microscopy maps optical and chemical properties at the ultimate source of electromagnetic radiation with spatial resolution beyond the diffraction limit of light, providing information that are not available from far-field measurement techniques. We are interested in exploiting the unique potential of near-field microscopy to visualize signatures of exciton-plasmon interaction at the nanoscale. In this presentation, our recent success in the development and applications of the near-field optical microscopy will be discussed. Near-field images of fundamental optical modes of sub-100 nm plasmonic nanostructures will be presented. The near-field localization in optical gap nanoantennas is directly visualized in real space with 10 nm spatial resolution (the highest resolution ever reported), mapping the amplitude and phase characteristics of the in-plane and out-of-plane vector components selectively. The direct observation of the orientation dependent optical response of chemically synthesized gold nanorods will be discussed, comparing the selective plasmon mode excitations by incident laser light and by local field. We will also present our progress toward accurate integration of nanomaterials using self-assembly procedures. Finally, I will share my teaching experience of this semester how we have successfully integrated the measurement resource of our modern research lab with the undergraduate teaching.