Raman 2D-Band Splitting in Graphene: Theory and Experiment

TL;DR

This study combines experimental and theoretical approaches to analyze how uniaxial tension affects the 2D Raman band in graphene, revealing complex line-shapes and strain-dependent splitting relevant for material stress assessment.

Contribution

It provides a comprehensive understanding of 2D Raman band splitting in graphene under strain through combined experimental and theoretical analysis.

Findings

2D mode exhibits complex line-shape due to two resonance processes

Splitting depends on strain direction and light polarization

Insights aid in stress assessment of graphene in composites

Abstract

We present a systematic experimental and theoretical study of the two-phonon (2D) Raman scattering in graphene under uniaxial tension. The external perturbation unveils that the 2D mode excited with 785nm has a complex line-shape mainly due to the contribution of two distinct double resonance scattering processes (inner and outer) in the Raman signal. The splitting depends on the direction of the applied strain and the polarization of the incident light. The results give new insight into the nature of the 2D band and have significant implications for the use of graphene as reinforcement in composites since the 2D mode is crucial to assess how effectively graphene uptakes an applied stress or strain.