Field-enhanced Raman scattering by silver nanoparticle with graded SiO2 coating

A reusable metallic substrate of surface-enhanced-Raman-scattering (SERS) was fabricated with field-enhancement property. Silver nanoparticles spread on a glass substrate and covered with a graded SiO2 coating were employed to enhance and to modulate the Raman scattering signal of probed samples. In the study, the Raman scattering enhancement of the crystal violet dye depended on the thickness of the SiO2 coating and the optimal Raman signal occurred as the SiO2 coating thickness was around 8.7 nm. Moreover, the SiO2 coating that functioned as a protector, maintaining the activity of the Ag nanoparticles, led to a reusable SERS-active substrate.