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

Abstract

The efficient SERS (surface enhanced Raman scattering) substrates that are \nfilms of nanoparticles (NP) of the “core–shell” type, where the core of SiO2, and the shell \nof gold nanoparticles, were developed in this work. Application of scanning electron \nmicroscopy and optical absorption enabled to find correlation between surface \nmorphology of nanostructures and position of the plasmon absorption band. It helped to \nadjust the latter to the wavelength of exciting laser radiation. It has been shown that the \ndesigned nanostructures are able to enhance electric field of an emitting dipole not only \ndue to adjustment of the band frequency for plasmon absorption to the wavelength of \nexciting laser radiation but also due to contribution of the so-called “hot spots” to \nenhancement of electric field scattering. Analysis of characteristics inherent to SERS \nsubstrates with nanostructures of the soil core – Au shell type has shown that they \nenhance the Raman signal by 5 orders higher as compared with the substrates based on \nSiO2 nanospheres not covered with gold nanoparticles.