Discrete dipole approximation analysis of plasmonic core/alloy nanoparticles

The surface plasmon resonance (SPR) properties of Au/AuxAg1−x core/alloy nanoparticles (NPs) have been investigated by means of the discrete dipole approximation. The core/alloy microstructure was varied by changing the shell alloy composition x, its thickness tS, and the shell thickness to core radius ratio (tS/rC) in the range of 0.05–1.0. These changes resulted in a novel tuning of SPR shape, frequency, and extinction. These models were compared with experimental results for Au/AuxAg1−x NPs prepared by a microwave-mediated hydrothermal processing method, which produces core/alloy NPs with SPR signatures closely resembling those of the models.