Nanoparticles and theory

This article provides an overview of recent work in the Schatz group concerned with using the discrete dipole approximation (DDA) to study the optical properties of silver and gold nanoparticles and other nanostructures, with emphasis on the determination of extinction and surface enhanced Raman scattering (SERS) spectra, and on near-field imaging. Computational electromagnetic methods provide an immensely useful approach for interpreting a wide range of nanoscience experiments, including the capability to describe optical properties of particles and other nanostructures up to several hundred nm in dimension, allowing for arbitrary particle structures and a complex dielectric environment. While there are many different methods for doing computational electromagnetics, the DDA method is one of the most useful, due to its ability to describe particles in three dimensions with modest computational resources. After a brief description of the method, we show its utility through applications to a variety of nanostructures, including triangular bifrustums, rods, gapped rods with roughened surfaces, rod-sheath structures and rings, including new results for many of the rod-structures.