Au-Ag Core-Shell Nanospheres for Surface-Enhanced Raman Scattering Detection of Sudan I and Sudan II in Chili Powder

Figure 4

UV-vis spectra of colloidal Au seeds and Au@Ag NPs synthesized with 1 mmol/L AgNO₃ solution and various amounts of Au seeds including (a) 0.45 mL, (b) 0.9 mL, (c) 1.5 mL, and (d) 4.5 mL.