Discrete Dipole Approximation Analysis of Plasmonic Core/Alloy Nanoparticles

• Published in: Chemphyschem 2014-08, Vol.15 (12), p.2582-2587
• Main Authors: Wu, Wenjie, Maye, Mathew M.
• Format: Article
• Language: English
• Subjects: Alloys; Chemistry; Colloidal state and disperse state; core/alloy structures; discrete dipole approximation; Exact sciences and technology; General and physical chemistry; nanoparticles; Physical and chemical studies. Granulometry. Electrokinetic phenomena; structure elucidation; surface plasmon resonance
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201402082

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. To the core: The surface plasmon resonance (SPR) of Au/AuxAg1−x core/alloy nanoparticles (NPs) has been studied by discrete dipole approximation (DDA; see figure). The SPRs were tunable by both alloy shell composition x and thickness tS. Through simulations of a series of core/alloy model NPs with x=0.2–0.8 and shell thickness to core radius ratio 0.05–1.0, the SPR features were compared with experimental measurements.