Faculty Publications

Title

Temperature-activated layer-breathing vibrations in few-layer graphene

Document Type

Article

Keywords

adsorption, few layer, graphene, layer breathing mode, Raman, shear mode

Journal/Book/Conference Title

Nano Letters

Volume

14

Issue

8

First Page

4615

Last Page

4621

Abstract

We investigated the low-frequency Raman spectra of freestanding few-layer graphene (FLG) at varying temperatures (400-900 K) controlled by laser heating. At high temperature, we observed the fundamental Raman mode for the lowest-frequency branch of rigid-plane layer-breathing mode (LBM) vibration. The mode frequency redshifts dramatically from 81 cm-1 for bilayer to 23 cm-1 for 8-layer. The thickness dependence is well described by a simple model of coupled oscillators. Notably, the LBM Raman response is unobservable at room temperature, and it is turned on at higher temperature (>600 K) with a steep increase of Raman intensity. The observation suggests that the LBM vibration is strongly suppressed by molecules adsorbed on the graphene surface but is activated as desorption occurs at high temperature. © 2014 American Chemical Society.

Original Publication Date

8-13-2014

DOI of published version

10.1021/nl501678j

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