Femtosecond laser melting and alloying in Au-Ag nanoalloys from colloid mixture of gold-silver nanoparticles

Abstract

Au-Ag nanoalloys have been successfully synthesized using femtosecond laser from the colloidal mixture of gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs). In the formation of Au-Ag nanoalloys, there was a phenomenon of laser melting and alloying. Au nanoparticles and Ag nanoparticles were prepared and were mixed with different compositions: Au20Ag80, Au30Ag70, Au50Ag50, Au70Ag30 and Au80Ag20. Each of the mixed colloid of Au NPs and Ag NPs was irradiated with laser femtosecond until Au-Ag nanoalloys were formed. The shifting of surface plasmon during alloying was observed using real-time monitoring with UV-Vis spectrophotometer every 5 min. The results showed that Au20Ag80, Au30Ag70, Au50Ag50 formed into Au-Ag nanoalloys in 15 min, while Au70Ag30 and Au80Ag20 formed into Au-Ag nanoalloys in 20 min.