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

Figure 7

In this figure nanoparticle solutions are pretreated with MBA (1.7 μM total concentration) and then titrated with KCl. The top panel is Raman scattering spectra of nanoparticles with preadsorbed MBA. The middle panel shows concurrently acquired extinction spectra. Concentrations are color-coded concentration as above, but now indicating KCl ranging from 1 μM (red) to 100 mM (blue). The figure at the bottom illustrates the variation of integrated Raman intensity (left scale, red diamonds) and aggregate-band extinction (right scale, green diamonds). The blue arrow indicates the band used in SERS intensity calculations.