Correlating the Structure, Optical Spectra, and Electrodynamics of Single Silver Nanocubes

The plasmonic properties of noble metal nanoparticles have potential uses in a wide variety of technologies, particularly sensing devices, based on their optical response. To better understand how nanoparticles can be incorporated in such devices, the detailed relationship between the optical response and structural properties of single nanoparticles is needed. Here we demonstrate that correlated localized surface plasmon resonance (LSPR) spectroscopy and high-resolution transmission electron microscopy (HRTEM) measurements can be used to obtain the optical response and detailed structural information for a single nanoparticle, using a silver (Ag) nanocube as the example. By carefully incorporating the HRTEM structural details into finite-difference time-domain (FDTD) electrodynamics calculations, excellent agreement with the LSPR measurements is obtained. The FDTD calculations show strong sensitivity between the nanocube optical response and the face-to-face width, corner and side rounding, and substrate of each cube, so careful determination of these parameters (1 nm resolution) is needed if theory and experiment are to match. In addition, the comparison of theory and experiment enables us to study the relative merits of the Johnson and Christy and Lynch and Hunter Ag dielectric data for describing perfect crystalline nanoparticles.