Tunable SERS Enhancement via Sub-nanometer Gap Metasurfaces.

ACS Appl Mater Interfaces

R.B. Annis School of Engineering, University of Indianapolis, Indianapolis, Indiana 46227, United States.

Published: April 2022

AI Article Synopsis

  • Raman sensing, especially combined with plasmonic nanostructures, effectively detects chemical signatures through surface-enhanced Raman spectroscopy (SERS).
  • The research demonstrates SERS with gold nanosphere metasurfaces featuring controllable subnanometer gap widths, revealing that signal enhancement increases as the gap narrows, with a quenching effect observed below 1 nm.
  • This study highlights the potential of subnanometer gap metasurfaces for exploring quantum effects and improving Raman-based sensors for various applications.

Article Abstract

Raman sensing is a powerful technique for detecting chemical signatures, especially when combined with optical enhancement techniques such as using substrates containing plasmonic nanostructures. In this work, we successfully demonstrated surface-enhanced Raman spectroscopy (SERS) of two analytes adsorbed onto gold nanosphere metasurfaces with tunable subnanometer gap widths. These metasurfaces, which push the bounds of previously studied SERS nanostructure feature sizes, were fabricated with precise control of the intersphere gap width to within 1 nm for gaps close to and below 1 nm. Analyte Raman spectra were measured for samples for a range of gap widths, and the surface-affected signal enhancement was found to increase with decreasing gap width, as expected and corroborated via electromagnetic field modeling. Interestingly, an enhancement quenching effect was observed below gaps of around 1 nm. We believe this to be one of the few studies of gap-width-dependent SERS for the subnanometer range, and the results suggest the potential of such methods as a probe of subnanometer scale effects at the interface between plasmonic nanostructures. With further study, we believe that tunable sub-nanometer gap metasurfaces could be a useful tool for the study of nonlocal and quantum enhancement-quenching effects. This could aid the development of optimized Raman-based sensors for a variety of applications.

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Source
http://dx.doi.org/10.1021/acsami.2c01335DOI Listing

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