Exploring the benefits of electron tomography to characterize the precise morphology of core-shell Au@Ag nanoparticles and its implications on their plasmonic properties

Abstract

In the design and engineering of functional core–shell nanostructures, material characterization at small length scales remains one of the major challenges. Here we show how electron tomography in highangle annular dark-field scanning transmission electron microscopy (HAADF-STEM) mode can be applied successfully to perform nano-metrological characterization of Au@Ag core–shell nanostructures. This work stresses the benefits of HAADF-STEM tomography and its use as a novel and rigorous tool for understanding the physical–chemical properties of complex 3D core–shell nanostructures. The reconstructed Au@Ag core–shell architecture was used as an input for discrete dipole approximation (DDA)- based electrodynamics simulations of the optical properties of the nanostructures. The implications of localized surface plasmon spectroscopy as well as Raman-enhanced spectroscopy are analysed.