In situ Raman Measurements of Suspended Individual Single-Walled Carbon Nanotubes under Strain

Abstract

We present a technique for in situ Raman measurements of suspended individual single-walled carbon nanotubes (SWNTs) under strain. We observe a strong change in the radial breathing mode intensity with increasing strain as the nanotube moves out of (or into) resonance, and for strain greater than approximately 2%, there is a clear irreversible upshift in the G-mode frequencies accompanied by an increase in intensity of a broad peak at a position associated with the D mode. For lower strain, the G-mode peaks (A1, E1, and E2) do not change significantly in position but change in relative intensity.

Additional curvature-induced Raman splitting in carbon nanotube ring structures

“…For the rings we measured, ␦ is in the range of Ϯ͑0.3-1.3 %͒ ͑"+" and "−" stand for stretch and compression, respectively͒, which is not big enough for obvious frequency shifts. This is in accord with the result reported by Lee et al 6 There are also many reports on the diameter dependence of G band frequencies for straight tubes in which the frequency shifts are attributed to phonon-dispersion induced by circumferential quantum confinement of the tubes. 12,[14][15][16] However, in our case, there are no clear dependence between the frequencies of the peaks and the diameters of the tubes in the rings.…”

“…31 The changes in electronic structures will affect the intensities, profiles, and frequencies of Raman peaks of CNTs. 1,3,5,6 At the presence of additional curvatures, similar mechanism may occur in rings. The changes in electronic structure would make the E v → E Ϯ1 c transitions resonate with the incident laser more efficiently, which consequently enhance the intensities of E 1 ͑E 1g ͒ and E 2 ͑E 2g ͒ modes in the Raman spectra.…”

“…Raman frequency shifts and intensity changes in CNTs under strain have been experimentally observed. [1][2][3][4][5][6] Most papers in this field mainly focus on straininduced Raman frequency shifts, however, the details of band structures changes and how it will effect the Raman spectrum have not been well illustrated yet.…”

Chirality-Dependent Raman Frequency Variation of Single-Walled Carbon Nanotubes under Uniaxial Strain

“…11,12 There have also been several experimental studies concerning the uniaxial strain induced Raman frequency variation of SWNTs. 10,[13][14][15][16] However, due to indirect measurement and low precision of uniaxial strain, different relations between uniaxial strain and Raman frequency were given, and the dependence on chirality was not yet observed.…”

Growth optimization of double-walled carbon nanotubes yielding precisely designed structures

“…The structure might be formed during evaporation of the water droplet and coalescence in a self-assembled fashion allows the formation of partitionlike structures [12]. We obtained suspended CNTs across the partition wall, which is expected to give a strong Raman signal [13]. Figure 6(b) is a Raman profile from the sample of Fig.…”