Size-dependent growth dynamics of silver-gold core-shell nanoparticles monitored by in situ second harmonic generation and extinction spectroscopy.

The in situ growth dynamics of colloidal silver-gold core-shell (Ag@Au CS) nanoparticles (NPs) are studied using time-dependent second harmonic generation (SHG) and extinction spectroscopy. Four sequential additions of chloroauric acid, sodium citrate, and hydroquinone are added to a silver nanoparticle solution to form a gold shell around a 45 nm silver core under different reaction conditions, resulting in final sizes ranging from 80 to 125 nm in diameter. In the first addition, a bumpy, urchin-like surface morphology is produced, while the second, third, and fourth additions provide additional nanoparticle growth with the surface morphology becoming more smooth and uniform, as shown using transmission electron microscopy measurements.

Growth Dynamics of Colloidal Silver-Gold Core-Shell Nanoparticles Studied by Second Harmonic Generation and Extinction Spectroscopy.

The growth dynamics of colloidal silver-gold core-shell (Ag@Au CS) nanoparticles (NPs) in water are monitored in a stepwise synthesis approach using time-dependent second harmonic generation (SHG) and extinction spectroscopy. Three sequential additions of chloroauric acid, sodium citrate, and hydroquinone are added to the silver nanoparticle solution to grow a gold shell around a silver core. The first addition produces a stable urchin-like surface morphology, while the second and third additions continue to grow the gold shell thickness as the surface becomes more smooth and uniform, as determined using transmission electron microscopy.