Multiphonon Raman Scattering in Graphene

TL;DR

This paper reports the observation of multiphonon Raman scattering in graphene, revealing layer-dependent intensity and frequency shifts that shed light on interlayer interactions.

Contribution

It presents the first detailed study of higher order multiphonon Raman modes in graphene layers, highlighting layer-dependent behaviors.

Findings

Higher order modes involve 3 and 4 phonons.

Mode intensity decreases with more layers.

Frequency upshifts linearly with layer number.

Abstract

We report multiphonon Raman scattering in graphene samples. Higher order combination modes involving 3 phonons and 4 phonons are observed in single-layer (SLG), bi-layer (BLG), and few layer (FLG) graphene samples prepared by mechanical exfoliation. The intensity of the higher order phonon modes (relative to the G peak) is highest in SLG and decreases with increasing layers. In addition, all higher order modes are observed to upshift in frequency almost linearly with increasing graphene layers, betraying the underlying interlayer van der Waals interactions.