Study of the C₆₀/Ag interface of a large area nanoarchitectured Ag substrate using surface-enhanced raman scattering

Plasmonic Ag nanopillars have been fabricated and used as a surface-enhanced Raman scattering (SERS) substrate. The effective surface area of the sample is determined using underpotential deposition (UPD) of thallium and agrees well with a geometrical calculation using ImageJ analysis of SEM images. In order to find the SERS enhancement factor (SEF), a similar sample is coated with Pt, which shows no plasmon response at the excitation wavelength of 532 nm. SEF values on the order of 10⁵ are obtained for Ag nanopillar substrates. Several monolayers of C₆₀ were deposited on these Ag nanopillars, and the Raman spectral results indicate charge delocalization at the interface between C₆₀ and Ag. FDTD simulation of the electric field confirms the experimental results; on the basis of these simulations, the electric field modulates with increasing diameter of the pillars, while the pitch (center-to-center distance) is fixed at 200 nm.