Surface-Enhanced Raman Scattering on Gold Nanohole Arrays in Symmetrical Dielectric Environments Exhibiting Electric Field Extension

The electromagnetic enhancement in surface-enhanced Raman scattering (SERS) caused by localized surface plasmon resonance is a near-field effect, often limiting the practicality of SERS in many applications. However, no attempts have been made to investigate field extension through symmetrical refractive index modulation in a SERS-based system. Here, we report the development and characterization of refractive index-matched SERS substrates supporting electric field extension to realize what is termed “long-range SERS” (LR-SERS). Finite-difference time-domain simulations were employed to tune the plasmonic responses and investigate electric field distributions of gold nanohole arrays (NHAs) as a function of the dielectric environment and geometric parameters. SERS substrates supporting long-range behavior were compared against “conventional” substrates without long-range behavior. SERS intensities from rhodamine 6G (R6G) aqueous solutions of 2.0 × 103 and 1.5 × 102 counts s–1 mW–1 were produced by the LR-S...