Field enhanced SERS on silver nano-particles substrate covered with a SiO2 buffer layer

The field enhanced Raman scattering of crystal violet (CV) molecules, excited by localized electromagnetic field of silver (Ag) nano-particles, is elucidated. In the study, a SiO₂ buffer layer with a gradient thickness is employed to prevent the electron-transfer from the Ag nano-particles to the CV molecules. Using a laser beam of 532nm to probe the CV dye, the Raman scattering intensity was a function of the thickness of the SiO₂ buffer layer. The maximum intensity of Raman signal was observed at the thickness of 8.5nm, where revealed a 61% increase of Raman scattering than that on an Ag nano-particles substrate without SiO₂ buffer layer. The field enhanced Raman scattering leads to a potential to improve the sensor sensitivity.