Plexciton for surface enhanced Raman scattering and emission

Plexcitons are polaritonic modes that result from coherently coupled plasmons and excitons. Far- and near-field properties of Ag/semiconductor core-shell nanoparticles on silica-coated silver substrate were theoretically studied, using finite-difference time-domain method. Our calculations suggested that titanium dioxide (TiO2) would be a better coating material, useful for the design of high-sensitive surface enhanced Raman scattering (SERS) substrate. The calculated Raman enhancement factor could be turned to as high as 4.0 x 10(10) under the 633-nm laser excitation. Surface plasmon-coupled emission of SERS reveals an optimal collection angle of 5 degrees, which shows a huge back scattering of the studied system. Our theoretical results could be used as a reference for the experimental design of semiconductor-based SERS substrate with high efficiency.