Surface-enhanced Raman scattering from silver nanostructures with different morphologies

Scanning electron microscopy and X-ray diffrac- tion reveal that four different types of crystalline silver nanostructures including nanoparticles, nanowires, nano- cubes, and bipyramids are synthesized by a solvothermal method by reducing silver nitrate with ethylene glycol using poly(vinylpyrrolidone) as an adsorption agent and adding different quantities of sodium chloride to the solution. These nanostructures which exhibit different surface plasma reso- nance properties in the ultraviolet-visible region are shown to be good surface-enhanced Raman scattering (SERS) sub- strates using rhodamine 6G molecules. Our results demon- strate that the silver nanocubes, bipyramids with sharp cor- ners and edges, and aggregated silver nanoparticles possess better SERS properties than the silver nanowires, indicating that they can serve as high-sensitivity substrates in SERS- based measurements.