Title: Synthesis and optical properties of colloidal Au-Ag alloy nanoparticles

Authors: Vu Duc Chinh; Nguyen Quoc Trung

Addresses: Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Dist., Hanoi, Vietnam ' Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Dist., Hanoi, Vietnam

Abstract: Colloidal gold-silver alloy nanoparticles (NPs) of variable composition were synthesised by sodium citrate reduction of mixed metal precursors at low concentrations. Scanning electron micrograph (SEM) images showed presence of particles in the 10-70 nm diameter range depending on the alloy compositions. A single surface plasmon resonance (SPR) peak observed in the visible spectrum proved the formation of homogeneous gold-silver alloy NPs. The position of the SPR absorption band maximum increased linearly with increasing gold content in the alloy NPs, ranging from 406 nm to 526 nm. No signicant change in surface plasmon bands was observed for fresh samples and after three months at room temperature indicating fair stability of the particles. Some alloy NPs show fluorescence emission peaks with blue and red shifts compared with the observed fluorescence from pure gold NPs.

Keywords: gold-silver alloys; nanoparticles; synthesis; SPR; surface plasmon resonance; fluorescence; nanotechnology; optical properties; colloidal Au-Ag alloys; sodium citrate.

DOI: 10.1504/IJNT.2015.067909

International Journal of Nanotechnology, 2015 Vol.12 No.5/6/7, pp.515 - 524

Available online: 08 Mar 2015

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