[UV-Vis studies on the course of reaction of Au/Ag alloy colloid with hydrogen tetrachloroaurate(III) hydrate].

Using citrate as protector, Au-Ag alloy nanoparticles with different molar ratios were prepared with hydrazine as the reducer. One plasmon band between monometallic Ag and Au was observed in their UV-Vis spectra. And the peak of alloy shifted linearly with the ratio of Au changing in the alloy. By UV-Vis spectra, the course of reaction of the alloy colloid with HAuCl4 was studied. The result shows that the UV-Vis spectra of the alloy colloid changed regularly with the adding volume of HAuCl4 increasing. And there is a linear interval in it with the change in the calculated ratio of Au. With the former studies, the course can be attributed to the dealloy of Au/Ag alloy.

[Preparation and surface enhanced raman spectroscopic studies on Au-Ag alloy nanoparticles].

Using citrate as protector, Au-Ag alloy nanoparticles with different molar ratios were prepared by using hydrazine as the reducer, One plasmon band between that of monometallic Ag and Au observed in their UV-Vis spectra indicated the formation of Au-Ag alloy nanoparticles. TEM results showed diameters about 25 nm and homogeneous color of the alloy nanoparticles without clear core-shell contrast. By using Pyridine as the probe molecules, SERS studies were performed. The results indicated the spectra of Pyridine adsorbed on alloy is different from that of Ag and Au.