SERS Mechanism on Graphene

TL;DR

This paper explores the SERS mechanism on graphene, emphasizing the role of ripples as surface roughness and challenging the chemical enhancement explanation, supported by spectral analysis and experimental data.

Contribution

It proposes that ripples, not chemical enhancement, are responsible for SERS on graphene, and shows quadrupole interactions are negligible in this system.

Findings

Ripples act as surface roughness causing SERS on graphene.

Quadrupole interactions are absent in graphene SERS.

Spectral analysis confirms the ripple-based SERS mechanism.

Abstract

The paper presents briefly some general points of the theory of Surface Enhanced Raman Scattering on metals, semiconductors, dielectrics and graphene. It is pointed out that the reason of SERS on graphene and some other 2D materials is not the chemical enhancement mechanism as it is widely accepted in literature, but ripples, which are necessarily present on a graphene surface and are analogues of the surface roughness, which is a reason of SERS. In addition, it is indicated that the quadrupole interaction, which arises in strong SERS is practically absent in the system with graphene. The results are confirmed by the analysis of the SERS, usual Raman and IR spectra of phthalocyanine molecule and by some other experimental data.