Surface-enhanced Raman scattering on tunable plasmonic nanoparticle substrates

摘要

Au and Ag nanoshells are investigated as substrates for surface-enhanced Raman scattering (SERS). We find that SERS enhancements on nanoshell films are dramatically different from those observed on colloidal aggregates, specifically that the Raman enhancement follows the plasmon resonance of the individual nanoparticles. Comparative finite difference time domain calculations of fields at the surface of smooth and roughened nanoshells reveal that surface roughness contributes only slightly to the total enhancement. SERS enhancements as large as 2.5 × 10¹⁰ on Ag nanoshell films for the nonresonant molecule p-mercaptoaniline are measured.