Resonant Raman Spectroscopy of Individual Strained Single-Wall Carbon Nanotubes

Abstract

Resonance Raman spectra of individual strained ultralong single-wall carbon nanotubes (SWNTs) are studied. Torsional and uniaxial strains are introduced by atomic force microscopy manipulation. Torsional strain strongly affects the Raman spectra, inducing a large downshift in the E2 symmetry mode in the G+ band, but a slight upshift for the rest of the G modes and also an upshift in the radial breathing mode (RBM). Whereas uniaxial strain has no effect on the frequency of either the E2 symmetry mode in the G+ band or the RBM, it downshifts the rest of the G modes. The Raman intensity change reflects the effect of these strains on the SWNT electronic band structure.

Tip-enhanced nano-Raman analytical imaging of locally induced strain distribution in carbon nanotubes

“…In addition, we took proper care to keep the sample in clean environment and made sure through Raman measurements that there was no carbonaceous contamination on the substrate as well. towards higher frequency under a torsional strain, whereas it shifts towards lower frequency under a tensile strain [39][40][41] .…”

“…The dragging method described above introduces local strains in the nanotube by rolling (torsional strain), stretching (tensile strain) or a combination of both [34][35][36] . TERS imaging, which involves Raman spectroscopy, is the best approach to visualize and analyse these local strains [37][38][39][40] . Raman scattering can even distinguish between torsional and tensile strains in CNTs because the G þ -mode around 1,590 cm À 1 in Raman scattering shifts Raman shift (cm -1 )…”

“…This process often develops local strain in the nanotubes. Although AFM-induced strains have been observed via confocal Raman spectroscopy with diffractionlimited spatial resolution [37][38][39][40] , it has not been easy to investigate the localized nature of such strains that can be confined within nanoscale region, which can significantly affect the device performance.…”

Study of Carbon Nanotube-Substrate Interaction

“…The G band Raman frequency depends sensitively on strain [47][48][49] and doping [50][51][52]. When the tube becomes metallic, the Kohn anomaly appears for the longitudinal optical (LO) phonon, which decreases and broadens the peak [51,53].…”

Directly observable G band splitting in Raman spectra from individual tubular graphite cones

“…Recently, we reported the growth of monochiral tubular graphite cones (TGCs), whose structure is similar to MWCNTs, on hundred micrometer sized carbon spherules [11,12]. They not only are highly crystalline with a single-crystal nanotip in nature, but also have long distance from the Si substrate, enabling us to probe individual TGCs without the influence of the substrate and other extraneous factors such as strain, bundling and deformation etc [13,14]. TGCs have also been reported with preferential zigzag monochirality detected by an electron diffraction technique in our previous work [11,15], offering a stable platform to study monochirality behaviour of tubular carbon based materials utilizing conventional Raman spectroscopy.…”