Raman Spectrum of Graphene and Graphene Layers

TLDR

Graphene serves as the two‑dimensional building block for all carbon allotropes of higher dimensionality. The D‑peak second‑order Raman feature changes in shape, width, and position with increasing layer number, reflecting band‑structure changes via a double‑resonant process. The Raman spectrum captures graphene’s electronic structure, with the G peak slightly down‑shifting, enabling unambiguous, high‑throughput, nondestructive layer identification—a capability currently lacking.

Abstract

Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality. We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers. The $D$ peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process. The $G$ peak slightly down-shifts. This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.