The role of a plasmonic substrate on the enhancement and spatial resolution of tip-enhanced Raman scattering

Abstract

We look to understand the enhancement and spatial resolution of a tip-enhanced Raman scattering (TERS) system containing a metal tip and plasmonic substrate.

Understanding the Role of Different Substrate Geometries for Achieving Optimum Tip-Enhanced Raman Scattering Sensitivity

“…Therefore, by scanning the tip across the sample surface one can realize Raman images of the materials to be probed with an excellent spatial resolution. For example, a resolution of 1.7 nm for carbon nanotubes [1], 3 nm for a Pd/Au bimetallic model catalyst [2], and 2.3 nm for MoS 2 [3] in ambient conditions using AFM-TERS and sub-nanometer resolution [4][5][6] for probing benzene rings via STM-TERS in ultra-high vacuum were reported.…”

Resonant tip-enhanced Raman scattering by CdSe nanocrystals on plasmonic substrates

“…31 Recently we employed gap-mode AFM-TERS for determining the local strain in mechanically transferred monolayers of MoS 2 on Au nanostructures. 8,26,32 The biaxial strain in an ultrathin MoS 2 layer induces a shi of the E 2g phonon mode, which is probed by TERS spectroscopy with a spatial resolution of less than 25 nm. 8 A dramatic Raman enhancement factor of 5.6 Â 10 8 accompanied by a high spatial resolution of 2.3 nm was achieved in gap-mode TERS for monolayer MoS 2 on Au nanodisks and allowed us to observe, for instance, the MoS 2 phase transition from 2H to 1T during TERS mapping.…”

The Expanding Frontiers of Tip-Enhanced Raman Spectroscopy

“…33,34 Although these early works attributed the enhanced Raman signal to the enhanced electric field located at the probe tip's apex, alternative enhancement mechanisms have also been proposed, including chemical enhancement 35 and a lightning rod effect. 36 Following the trends established in SERS, three of the first groups focused on dye molecules. These very early works reported a spatial resolution of about 50 nm.…”