Gold nanorods: Limitations on their synthesis and optical properties

Au nanorods are synthesized, in aqueous solution, with a rather large yield (>79%) and narrow size distribution by using a seed-mediated method. The remaining particles are spheres, cubes and unshaped particles. The size distribution of gold nanorods is markedly influenced by the experimental parameters and as we point out there are limitations on the shape and size reproducibilities of these nanorods. Transmission electron microscope (TEM) and Absorption Spectroscopy investigate structural and optical properties, respectively. Simulations of the absorption spectra using the discrete dipole approximation (DDA) method are presented for gold nanocubes. This makes it possible to assign the various absorption peaks observed for a collection of nanocrystals with nanorods, cubes and spheres.