Efficient core-SiO₂/shell-Au nanostructures for surface enhanced Raman scattering

Abstract

The efficient SERS (surface enhanced Raman scattering) substrates that are films of nanoparticles (NP) of the “core–shell” type, where the core of SiO2, and the shell of gold nanoparticles, were developed in this work. Application of scanning electron microscopy and optical absorption enabled to find correlation between surface morphology of nanostructures and position of the plasmon absorption band. It helped to adjust the latter to the wavelength of exciting laser radiation. It has been shown that the designed nanostructures are able to enhance electric field of an emitting dipole not only due to adjustment of the band frequency for plasmon absorption to the wavelength of exciting laser radiation but also due to contribution of the so-called “hot spots” to enhancement of electric field scattering. Analysis of characteristics inherent to SERS substrates with nanostructures of the soil core – Au shell type has shown that they enhance the Raman signal by 5 orders higher as compared with the substrates based on SiO2 nanospheres not covered with gold nanoparticles.