Issue 6, 2024

Resonant Raman scattering on graphene: SERS and gap-mode TERS

Abstract

Nanoscale deformations and corrugations occur in graphene-like two-dimensional materials during their incorporation into hybrid structures and real devices, such as sensors based on surface-enhanced Raman scattering (SERS-based sensors). The structural features mentioned above are known to affect the electronic properties of graphene, thus highly sensitive and high-resolution techniques are required to reveal and characterize arising local defects, mechanical deformations, and phase transformations. In this study, we demonstrate that gap-mode tip-enhanced Raman Scattering (gm-TERS), which offers the benefits of structural and chemical analytical methods, allows variations in the structure and mechanical state of a two-dimensional material to be probed with nanoscale spatial resolution. In this work, we demonstrate locally enhanced gm-TERS on a monolayer graphene film placed on a plasmonic substrate with specific diameter gold nanodisks. SERS measurements are employed to determine the optimal disk diameter and excitation wavelength for further realization of gm-TERS. A significant local plasmonic enhancement of the main vibrational modes in graphene by a factor of 100 and a high spatial resolution of 10 nm are achieved in the gm-TERS experiment, making gm-TERS chemical mapping possible. By analyzing the gm-TERS spectra of the graphene film in the local area of a nanodisk, the local tensile mechanical strain in graphene was detected, resulting in a split of the G mode into two components, G+ and Gāˆ’. Using the frequency split in the positions of G+ and Gāˆ’ modes in the TERS spectra, the stress was estimated to be up to 1.5%. The results demonstrate that gap-mode TERS mapping allows rapid and precise characterization of local structural defects in two-dimensional materials on the nanoscale.

Graphical abstract: Resonant Raman scattering on graphene: SERS and gap-mode TERS

Supplementary files

Article information

Article type
Paper
Submitted
15 Oct 2023
Accepted
03 Jan 2024
First published
23 Jan 2024
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2024,14, 3667-3674

Resonant Raman scattering on graphene: SERS and gap-mode TERS

N. N. Kurus, V. Kalinin, N. A. Nebogatikova, I. A. Milekhin, I. V. Antonova, E. E. Rodyakina, A. G. Milekhin, A. V. Latyshev and D. R. T. Zahn, RSC Adv., 2024, 14, 3667 DOI: 10.1039/D3RA07018B

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