Optical and chemical properties of silver tree-like structure treated with gold galvanic substitution

Galvanic gold substitution was executed in the presence of trisodium citrate on silver tree-like structures. No discernible difference in geometry was observed between the pre- and post-gold substitution phases, which benefited from the presence of citrate ions. The extent of gold substitution was regulated by the amount of gold ion solution added. After the gold substitution, an increase in extinction was observed in the ultraviolet region, indicating that gold was deposited at the surface. Raman scattering of para-toluenethiol was measured on the gold/silver tree-like structures at 488 nm excitations, where a decrease in the Raman peak intensity was observed as the quantity of gold ion solution increased. The results indicated that the optical property of silver was lost due to the increase of the amount of gold deposition. Concurrently, an investigation was conducted into the chemical resistance of the gold/silver tree-like structures, which was evaluated by measuring the resistivity inverse-proportional to the amount of silver ions dissolved by the diluted nitric acid. As the amount of gold ion solution added increased, the resistivity increased and became constant. The result implied that the surface chemical property had undergone a complete transformation into gold.