Silver Nanoparticles as Enhancing Substrates for Raman and Fluorescence Spectroscopy

The enhancing properties of silver nanopaxticles in surface-enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF) are studied in this work. The obtained results confirm that the partial aggregation of nanopaxticles leads to a great increase of Raman scattering cross-section but there are significant differences in SERS-activity of colloidal silver treated with various aggregating compounds. The differences are interpreted through the analysis of both experimental and computational results. The same silver colloid covered with silica shell preventing the fluorescence quenching makes possible a several-fold increase in fluorescence emission. The effect strongly depends on thickness of the outer layer of nanopaxticles. Geometrical parameters of nanoparticles (radius or radius and thickness of the adsorption layer in core-shell systems) are determined on the basis of the dynamic light scattering (DLS) data and extinction spectra analysis.