The electromagnetic effect in surface enhanced Raman scattering: Enhancement optimization using precisely controlled nanostructures

This article presents an overview of surface enhanced Raman scattering (SERS) studies using substrates realized with fabrication techniques that provide a precise control of the geometry of metallic nanostructures. The role of the localized surface plasmons resonance (LSPR) in SERS is especially emphasized since it can be studied systematically thanks to the substrates produced by these fabrication techniques. We therefore explain why a precise control of the LSPR position is important in order to optimize the SERS intensity. The leading fabrication techniques (self-assembly and nanolithography) that ensure a precise control of all the geometrical parameters of the fabricated nanostructures and, as a consequence, a precise control of the LSPR are then described. The largest part of this article is focused on the identification of the main parameters governing the SERS intensity through the LSPR position such as nanoparticle size and shape (principally cylindrical, triangular, square, and elongated sections), higher orders LSPR, excitation polarization and excitation wavelength. The studies done on the optimization of the SERS intensity in the last 10 years is then summarized. We finally describe the studies made on the near-field coupling between the nanoparticles and emphasize its potential before exploring other kind of controlled nanostructures used to increase the SERS intensity.

► Role of the localized surface plasmon resonance in surface enhanced Raman scattering. ► Emphasize on fabrication techniques which provide a high control of the geometry of metallic nanostructures. ► Identification of the main parameters governing the SERS intensity through the LSPR position. ► Summary of the systematical studies done to optimize the SERS efficiency.