Surface-enhanced Raman scattering of methylene blue adsorbed on cap-shaped silver nanoparticles

Silver nanocaps were prepared by chemical synthesis combined with physical evaporation technique, and characterized using TEM, SEM and UV–vis-NIR spectroscopy. The surface-enhanced Raman scattering (SERS) activities of these nanoparticles were investigated using methylene blue (MB) as probe molecule. The enhancement factor was estimated to be as large as 4.2 × 107. The results demonstrate that these silver nanocaps are promising for SERS applications in detection and analysis of molecules.