Controlling Raman enhancement in particle-aperture hybrid nanostructures by interlayer spacing

TL;DR

This study demonstrates how adjusting interlayer spacing in layered nanostructures can precisely control surface-enhanced Raman spectroscopy signals, combining experimental and simulation approaches for tunable plasmonic enhancement.

Contribution

It introduces a method to tune SERS enhancement by controlling interlayer spacing in particle-aperture nanostructures using DNA-assisted lithography.

Findings

Raman enhancement can be modulated by interlayer spacing.

Finite difference time domain simulations support experimental results.

Field enhancements are tunable through structural adjustments.

Abstract

Here we show how surface-enhanced Raman spectroscopy (SERS) features can be fine-tuned in optically active substrates made of layered materials. To demonstrate this, we used DNA-assisted lithography (DALI) to create substrates with silver bowtie nanoparticle-aperture pairs and then coated the samples with rhodamine 6G (R6G) molecules. By varying the spacing between the aperture and particle layer, we were able to control the strength of the interlayer coupling between the plasmon resonances of the apertures and those of the underlying bowtie particles. The changes in the resulting field enhancements were confirmed by recording the Raman spectra of R6G from the substrates, and the experimental findings were supported with finite difference time domain (FDTD) simulations including reflection/extinction and near-field profiles.