Star-shaped Silver Nanoparticles as SERS Substrates for Trace Analysis of Polycyclic Aromatic Hydrocarbons

摘要

Different methodologies have been developed for the synthesis and optimization of anisotropic metallic nanostructures, particularly with gold and silver, aiming at establishing connections between their morphology, their optical properties and their. potential to be used on chemical analysis via SERS (Surface-enhanced Raman Scattering).' In particular, colloidal metal particles with sharp tips, such as nanostars, have the potential to focalize plasmonic electromagnetic fields, suggesting a significant potential to be used as SERS substrates.2 We describe in this work the performance of silver nanostars as substrates for SERS study of two polycyclic aromatic hydrocarbons (PAHs), an important class of environmental pollutants formed mainly as a result of the incomplete combustion of organic materials. The investigated analytes are anthracene and 9-nitroanthracene. Density functional theoretical (DFT) calculations for normal Raman and SERS spectra were performed for a reliable analysis of specific molecule-surface interaction and to support the enhancement patterns observed in each SERS spectra.