文摘
Plasmonic properties of arrays of gold nanodisks were investigated to study the localization of the near-field enhancement at the surface of the nanodisks. To measure the near field, surface-enhanced Raman spectroscopy (SERS) was performed on different kinds of substrates with and without an over layer of silica that disabled the possibility for our SERS probe to adsorb on the top of our structures. Thanks to this, we were able to determine, depending on the substrate, which fraction of the SERS enhancement was coming from the top of our structures. We demonstrate that the near-field enhancement is mainly localized at the top of the nanodisks in the case of dielectric substrate, whereas it comes from the nanodisk side for metallic subfilm substrate.