Plasmonic nanocrescents are asymmetric structures with non-uniform, polarization dependent near-field distributions. We investigated the near-field distribution of nanocrescents using localized photo-polymerization. Polymerization of SU-8 photoresist was initiated through two-photon absorption (TPA). AFM was used to visualize the topography of cross-linked polymer relative to gold nanocrescents. Due to the sensitivity of TPA to local intensity, we expected areas of cross-linked polymer to represent the spatial distribution of enhanced fields. After exposure and development of SU-8 coated nanocrescents, polymerized regions were characterized with AFM and results were compared to scanning electron microscopy (SEM) analysis. We observed a strong polarization dependence of the near-field due to the different plasmon resonance modes which were excited. Regions of polymerized SU-8 were partially correlated with the near-field distributions predicted by simulations. A better understanding of the near-field plasmonic nanocrescents has implications for applications of the structures in sensing and spectroscopy.

Multi-photon photochemistry to map the local fields of plasmonic nanocrescents

245th National Meeting (2013)

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