Raman Spectral Probing of Electronic Transition Energy E_ii Variation of Individual SWNTs under Torsional Strain

Abstract

We present herein a rational approach to probe the torsional strain-induced electronic transition energy Eii variation of individual SWNTs by resonant Raman spectroscopy (RRS). When a SWNT was manipulated by AFM tip through a path perpendicular to SWNT axis, both torsional and uniaxial strain would be introduced in SWNTs. Under the torsional strain, resonant Raman spectral mapping along a SWNT detected an M-shaped frequency (omegaRBM) and W-shaped intensity (IS) variation of radial breathing mode (RBM) spectra, which were induced by the elastic retraction of the nanotubes in combination with the friction after the tip has been removed. The electronic transition energy Eii variation along SWNTs by torsional strain follows a family pattern based on q=(n - m) mod 3: for semiconducting SWNTs, E33S increases for q=+1, E33S decreases and E22S increases for q=-1, and for metallic SWNTs, E11M always increases.

Resonance Raman spectroscopy in Si and C ion-implanted double-wall carbon nanotubes

“…Actually, it has been shown that RBM is strongly dependent on the kind of deformation imposed on the tubes. 15 Figure 3 shows the Raman spectra of pristine and Siimplanted DWNTs, in the region of the disorder-induced D band, and the G band. Regardless of the laser energy used for excitation, the D band is very weak in the Raman spectra of the pristine samples, indicating that the samples are of high crystalline quality.…”

Combination of atomic force microscopy and photoluminescence microscopy for the investigation of individual carbon nanotubes on sapphire surfaces

“…Its diameter of 1.12 nm agrees well with that determined by the AFM. The map B demonstrates unusually broad PL in the region of (11,7), (12,5) and (10,9)-tubes [11]. Note that the diameters of these tubes (∼1.2 nm) are definitely smaller than the AFM value (∼1.6 nm).…”

“…Local perturbations such as sharp bends or break sites are also expected to strongly affect the electronic properties of SWNTs. For instance, Gao et al have shown the influence of torsional strain on the electronic transition energies after AFM manipulation [5]. Here, we describe in detail an approach which combines AFM and PL microscopy to investigate individual and aggregated SWNTs on surfaces.…”

The Intramolecular Junctions of Carbon Nanotubes

“…Therefore, the local DOS at the Fermi level decreased and a bandgap formed, which caused the drastic decrease of the conductivity. [101,102] The change of local DOS can be detected from the tunneling spectroscopy by STM measurement of a mechanically distorted SWNT. [103] Moreover, torsional deformation can also alter the electronic properties of CNTs.…”