Surface-enhanced Raman scattering from bowtie nanoaperture arrays

This paper is dedicated to Professor P.R. Norton on the occasion of his 75th birthday, in honor of his profound contributions to Surface Science. Bowtie nanoaperture arrays with different tip-to-tip distances were fabricated on thin gold film by focused ion beam (FIB) milling. White light transmission spectra for all the bowtie nanoaperture arrays were collected and the relationship between the tip-to-tip distance and the surface plasmon resonance (SPR) frequency was evaluated. Finite-difference time domain (FDTD) simulations were carried out for the white light transmission and for the local field intensity with the aim of correlating the optical transmission peaks to the tip-to-tip distances. Surface-enhanced Raman scattering (SERS) was collected from bowtie nanoaperture arrays coated with rhodamine 6G. It was found that the SERS properties vary with the tip-to-tip distances of the bowties of same aperture size and same periodicity. The relationships between SERS, SPR frequency and the local field intensity are discussed. (C) 2018 Elsevier B.V. All rights reserved.