Spatial confinement model applied to phonons in disordered graphene-based carbons

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• 作者：Pascal Puech ; ^{pascal.puech@cemes.fr" class="auth_mail" title="E-mail the corresponding author} ; Jé ; ré ; mie-Marie Plewa ; Philippe Mallet-Ladeira ; Marc Monthioux
• 刊名：Carbon
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：105
• 期：Complete
• 页码：275-281
• 全文大小：808 K

文摘

Analyzing the various bands in Raman spectra, mostly the G (optical carbon–carbon mode) and D (defect-related double resonance process) bands, is powerful at characterizing defects in disordered graphene-based carbons. The crystallite size L_a could be estimated from the I_D/I_G (intensity) or A_D/A_G (area) ratio, but with large uncertainties. Using the spatial confinement model (SCM) of the phonons has fully explained the linewidth variation for the D band, but could not explain the linewidth variation for the G band over the whole L_a range. Indeed, if the latter for large, Bernal-stacked graphenes is due to the Kohn anomaly and can be explained considering phonon dispersion curves, turbostratically-stacked graphenes with small L_a generate an additional broadening of the G band not accounted by the phonon-related SCM only. The realistic SCM proposed here explains the way the G band shape is related to L_a. The model was also validated by successfully duplicating the evolution of the D (mostly related to the electronic band dispersion) and D′ band linewidths with decreasing L_a down to 5 nm. The work aims to be a guide for future computational works on Raman spectra of graphene-based carbon materials.