Using Femtosecond Laser Irradiation To Grow the Belly of Gold Nanorods

Irradiation of gold nanorods can lead to the formation of several new nanostructures. One of the most interesting among them are ϕ-shaped rods, a stable intermediate shape in the rod-to-sphere conversion process, but not much attention has been paid to their characterization. In this work, we irradiated colloidal rods, looking for the conditions to maximize the generation of ϕ-shaped structures. The shape and dimensions of the irradiated samples were then statistically analyzed. Moreover, we have calculated the energy range within which such transformation into ϕ-shaped rods takes place, which has been determined to be a very narrow energy window (between 0.38 and 0.41 eV/atom). Finally, we have performed simulations to characterize the optical response of such structures.