Onset of Intense Surface Enhanced Raman Scattering and Aggregation in the Au@Ag System

Figure 3

Raman scattering spectra of titrants (SERS labels) rhodamine 6G (R6G, top), 4-mercaptopyridine (MPY, middle), and 4-mercaptobenzoic acid (MBA, bottom) as these are titrated into ca. 1 nM Au@Ag core-shell nanoparticles. Titrant concentrations are as indicated in color bar and range from 1 nM (red) to 1 mM (blue). Peaks are consistent with values reported in the literature [56]. The blue arrows indicate the peaks used for SERS integral intensity calculations.