Preparation Of Ag-Au Alloy Nanopaticles And Its Surface Enhanced Raman Scattering Studies

In this paper, bigger Ag-Au nanoparticles were prepared by two steps method with sodium citrate and hydroxylamine as reductant subsequently. UV-Vis spectrum, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX) were adoptted to characterized nanoseeds and bigger nanoparticles after growing, and mechanism of growing was proposed. Furthermore, Surface Enhanced Raman Scattering spectra of thiophenol (TP), p-Aminothiophenol (PATP) and 2,2'-bipyridine(2,2'-bpy) on alloy nanoparticles were studied under excitation lines at 632.8 and 1064nm respectively.From UV-Vis spectra, only one maximum absorption band appeared in both nanoseeds and nanoparticles after growing between absorption bands of Ag and Au. TEM and SEM images of alloy nanoparticles show homogeneous color rather than light and shade contrast of core-shell nanoparticles, while compared to alloy nanoseeds they presented coarser surface. The results of EDX indicated that the composition of alloy nanopartilces was changed compared with nanoseeds, this might be caused by the use of different reductant. So it was deduced that growing process was in virtue of alloy nanoseeds and AgCl sols. SERS studies of PATP and 2,2'-bpy revealed that the surface composition of alloy nanoparticles contained both Ag and Au atoms. Moreover, from the results of SERS spectrum of TP under different excitation lines, under excitation line 632.8nm and 1064nm SERS intensities were increased with the increase of Au mole fraction, it could be concluded that SERS were contributed by surface plasma resonance enhancement mechanism.