Similarities in the Raman RBM and D bands in double-wall carbon nanotubes

Abstract

We have examined several sets of heterogeneous double wall carbon nanotubes and analysed the frequency in a wide range of values. We have found that a statistical correlation exists between the D band intensity and the RBMs intensity. All the sample sets show a correlation of the RBM and D Raman intensity which is monotonic and non-linear using the 514nm laser excitation. Our results suggest that a similar mechanism is at the origin of the RBM and D bands. These results are corroborated by observations on carbon nanotubes embedded in a polymer matrix. We derive the phonon potential deformation for the D band and extend the excitation wavelength dependence of the D band to the UV. The intensity of the D band decreases with increasing hydrostatic pressure and fanishes at a pressure comparable to what has been observed earlier for the RBM and D* band.

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

“…(b) Raman spectra of Double Wall Carbon Nanotubes (DWCNTs) filled with PbI 2 . Reprinted from Ref [498]. with permission.…”

Raman bands of double‐wall carbon nanotubes: comparison with single‐ and triple‐wall carbon nanotubes, and influence of annealing and electron irradiation

“…17 For the D band, it was shown that the band is diametersensitive, and in the case of DWCNs one can expect a contribution from both inner and outer tubes, located at different wavenumbers. Unfortunately, the splitting at lower pressures cannot be followed with a diamond pressure cell because of the Raman signal from diamond and the fact that the D band disappears 26 at around 3 GPa. In the DWCNT samples used here, the large diameter distribution leads to a contribution that can be fitted with a single Lorentzian, while with DWCNTs obtained from peapods, the D-band shape is due to a double contribution.…”

“…We note that both the excitation wavelengths used here are not strongly absorbed. 26 A decrease of 10 cm 1 would correspond to a heating of approximately 500°C. But we do not observe any broadening, which should be present if heating does occur.…”

“…Furthermore, it has been observed that the intensity of the D band is correlated to the RBM intensity as long as the defect density is not too high. 26 In this paper, we first present experimental studies to show how the shape of the G band changes with the number of walls and discuss in detail the origin of these differences. Then, we carry out a statistical analysis of the intrinsically inhomogeneous system to draw general conclusions on the Raman spectra of DWCNTs.…”

Ultraviolet photon absorption in single- and double-wall carbon nanotubes and peapods: Heating-induced phonon line broadening, wall coupling, and transformation

“…No Raman D band is observed for glassy carbon when excited at 257 nm and for DWNTs excited at 325 nm. 5 Radial breathing modes are more difficult to observe due to the spectral cutoff performance of spectrometers in the ultraviolet spectral region.…”