Defect characterization in graphene and carbon nanotubes using Raman spectroscopy

Abstract

This review discusses advances that have been made in the study of defect-induced double-resonance processes in nanographite, graphene and carbon nanotubes, mostly coming from combining Raman spectroscopic experiments with microscopy studies and from the development of new theoretical models. The disorder-induced peak frequencies and intensities are discussed, with particular emphasis given to how the disorder-induced features evolve with increasing amounts of disorder. We address here two systems, ionbombarded graphene and nanographite, where disorder is represented by point defects and boundaries, respectively. Raman spectroscopy is used to study the 'atomic structure' of the defect, making it possible, for example, to distinguish between zigzag and armchair edges, based on selection rules of phonon scattering. Finally, a different concept is discussed, involving the effect that defects have on the lineshape of Raman-allowed peaks, owing to local electron and phonon energy renormalization. Such effects can be observed by near-field optical measurements on the G feature for doped single-walled carbon nanotubes.

Effect of Residual Gas Composition on Epitaxial Growth of Graphene on SiC

“…Parameter 12 cm −2 /1 cm −1 is approximately a proportionality factor between G peak position and graphene charge density, as determined theoretically [24] and confirmed experimentally [23,25]. Graphene grain size L a can be determined from the ratio I G /I D [26][27][28][29] of integrated G peak intensity (I G ) and D peak intensity (I D ),…”

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

“…We do not expect that the Raman signature of the as-prepared CDs is buried by fluorescence because the D-and G-peaks arise from resonant Raman scattering, which has a similar intensity as fluorescence. 49,50 After repeated CW laser exposure, the intensity of the fluorescence signal decreased significantly. It took only a few seconds until the fluorescence intensity dropped to about 50% of its original value, indicating that the nitrogen or oxygen-based groups fade away.…”

Influence of architecture on the Raman spectra of acid-treated carbon nanostructures

“…According to the double resonance theory, the crystal defects scatter the excited electrons resulting in the wave vector condition, making the intensity of the D band defect dependent. The larger the number of defects, the higher the D band's intensity [6,[23][24][25]. For the case of SWCNTs, a broad line width of the D band is considered as an indication of the presence of defects, impurities and/or amorphous carbon [6].…”