Study of the C60/Ag Interface of a Large Area Nanoarchitectured Ag Substrate Using Surface-Enhanced Raman Scattering

Abstract

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.