Journal article
Diameter dependence of the defect-induced Raman modes in functionalized carbon nanotubes
Publication Details
Authors: | Backes, C.; Laudenbach, J.; Schmidt-Isenbeck, D.; Herziger, F.; Hennrich, F.; Kappes, M.; Muoth, M.; Haluska, M.; Hof, F.; Hauke, F.; Hirsch, A.; Maultzsch, J. |
Publisher: | PERGAMON-ELSEVIER SCIENCE LTD |
Publication year: | 2017 |
Journal: | Carbon |
Pages range : | 1-7 |
Volume number: | 112 |
Start page: | 1 |
End page: | 7 |
Number of pages: | 7 |
ISSN: | 0008-6223 |
DOI-Link der Erstveröffentlichung: |
Abstract
Covalent functionalization of single-walled carbon nanotubes typically leads to an intensity increase of the defect-induced Raman mode (D mode). A large intensity ratio of the D and G modes (D/G ratio) is therefore often used as evidence for a successful functionalization. Here, we discuss the effect of the D mode resonance on the D/G ratio and compare pristine and covalently functionalized nanotubes. By resonance Raman spectroscopy we study the evolution of the lineshape and frequencies of the D and 2D modes of samples enriched with semiconducting and metallic nanotubes in comparison with the radial breathing mode. First, we experimentally demonstrate the dependence of the D- and 2D-mode frequencies on the tube diameter and derive an analytical expression for both frequencies as a function of the diameter and the optical transition. Furthermore, we demonstrate that the contribution of the D and 2D modes for small SWCNTs disappears in covalently functionalized samples due to partial destruction. In fact, this can change the measured D/G ratio significantly and has a fundamental impact on the determination of the degree of SWCNT functionalization by Raman spectroscopy. (C) 2016 Elsevier Ltd. All rights reserved.
Covalent functionalization of single-walled carbon nanotubes typically leads to an intensity increase of the defect-induced Raman mode (D mode). A large intensity ratio of the D and G modes (D/G ratio) is therefore often used as evidence for a successful functionalization. Here, we discuss the effect of the D mode resonance on the D/G ratio and compare pristine and covalently functionalized nanotubes. By resonance Raman spectroscopy we study the evolution of the lineshape and frequencies of the D and 2D modes of samples enriched with semiconducting and metallic nanotubes in comparison with the radial breathing mode. First, we experimentally demonstrate the dependence of the D- and 2D-mode frequencies on the tube diameter and derive an analytical expression for both frequencies as a function of the diameter and the optical transition. Furthermore, we demonstrate that the contribution of the D and 2D modes for small SWCNTs disappears in covalently functionalized samples due to partial destruction. In fact, this can change the measured D/G ratio significantly and has a fundamental impact on the determination of the degree of SWCNT functionalization by Raman spectroscopy. (C) 2016 Elsevier Ltd. All rights reserved.
