Hierarchical silver mesoparticles with tunable surface topographies for highly sensitive surface-enhanced Raman spectroscopy

Using a simple aqueous synthesis method, Ag hierarchical mesoparticles with tunable surface topography were obtained. The mechanism of tuning the topographies of the hierarchical mesoparticles in this particle-mediated anisotropic growth system was studied. A series of Ag mesoparticles with well-tuned surface topographies were synthesized as an ideal research target for a systematic investigation of the effect of surface nanostructures on the performance of surface enhanced Raman spectroscopy (SERS). Highly-branched Ag mesoparticles were shown to have the highest SERS sensitivity both as single-particle SERS substrates and particle-array SERS substrates, which have an enhancement factor greater than 10⁹. Using the finite difference time domain method, the distribution of the localized electromagnetic field near the particle surface was simulated. Based on the simulation results, the mechanism of the effect of topography on the SERS properties was systematically studied.