New Nano Architecture for SERS Applications

Silver silica gold sandwich nanoparticles were synthesized by a multistep seeded growth process and were characterized by UV-vis spectroscopy, transmission electron microscopy, and X-ray diffraction. Gold islands allow passage of light through the crevices into the silica layer, and the silver core-silica shell behaves like a mirror, thus reflecting the light incident on it. These structures facilitate light amplification due to mixing of light waves from the multiple reflections. Sandwich nanopartides show SERS enhancement of similar to 10(6). This enhancement factor is 6-fold larger in magnitude than that of similar nanoparticles without the silver core under identical experimental conditions.