Radial breathing mode, RBM

Raman spectroscopy is one of the most powerful techniques for the characterization of nanocarbons. It is also a convenient technique because it involves almost no sample preparation and leaves the material unharmed. There are four characteristic bands for CNTs The band at 200 cm-1 is called radial breathing mode (RBM). It depends on the curvature and can be used to calculate the diameter of SWCNTs [61]. The relatively broad D-band at 1340 cm-1 is assigned to sp2-related defects and disorder in the graphitic structure of the material. The tangential C-C stretching mode is located at -1560 cm 1 (G-band). The second order mode of the D-band can be observed (G -band,... 

The Raman spectrum of HiPco SWNT obtained at the He-Ne laser excitation of 1.96 eV has three characteristic regions four bands in the low frequency region at 100-300 cm 1 (radial breathing mode (RBM)), two intensive bands at 1500-1600 cm 1 (tangential mode (G-mode)) of the spectrum and D mode (near 1300 cm"1) [14-18], At He-Ne laser excitation 4 intensive bands (RBM) are observed in Raman spectra of HiPCO nanotubes, corresponding to SWNTs of different diameters and chirality. 

Fig. 5.7 Raman spectrum of SWNTs excited by 785-nm CW radiation. The observed peaks around 1,590, 1,300, and 260 cm correspond to the tangential graphite-like modes (G-band), the disorder-induced modes (D-band), and the radial breathing modes (RBM), respectively [27]...

SWCNTs, DWCNTs, or MWCNTs with very small inner-tube diameters show another size-dependent Raman feature in the low-frequency range referred to as radial breathing modes (RBMs) [35, 39, 40]. The RBMs are considered as a clear indicator for the presence of CNTs, since this Raman feature is unique to CNTs and is not observed for other carbon materials. As suggested by the name, the RBM is a bond-stretching, out-of-plane mode, where all carbon atoms vibrate simultaneously in the radial direction. The RBM frequencies are between 100 and 400 cm and were found to be inversely proportional to the tube diameter [41 3]. In case of DWCNTs and small-diameter MWCNTs, RBM frequencies higher than 200 cm are ascribed to inner tubes while lower frequencies can be associated with both, inner and outer tubes [44, 45]. SWCNTs typically exhibit... 

The imaging of single-walled carbon nanotubes (SWNTs) has become the most frequent application of TERS [23-25]. SWNTs have generated intense interest due to their potential applications in nanotechnology. Four types of Raman mode are usually observed in the TER spectra of SWNT the radial breathing modes (RBM), two graphitic bands (G, G ), and the disordered (D) band. The positions of these bands are vibrational signatures of the state of the SWNT, for example, its defect density, chirality, and so on. 

Figure 7. Raman spectrum ofSWNT before (line) and after 2MeV, electron beam radiation dose of 60(closed circles), 180 (open circles) and 240 kGy (closed triangles). Inset Radial breathing mode (RBM) sections of the...

From their first measurement and theoretical discussion on, the Raman spectra of carbon nanotubes provided valuable information on the shape and composition of the structure. They can also serve to prove the existence or nonexistence of nanotubes in a sample, which is assessed, among others, by considering a distinct Raman band. It is called radial breathing mode (RBM) band and corresponds to a synchronous radial vibration of all carbon atoms in perpendicular to the tube s axis. This band is the characteristic of the nanotube stracture, and for the time being, nothing Hke this has ever been observed for any other carbon material studied. 

The radial breathing mode (RBM) appearing in the 160 to 300cm region is associated with a symmetric movement of aU carbon atoms in the radial direction (Fig. 15.18a)... 

Figure 9.2 shows the main spectral features of the Raman spectrum of a SWCNT, namely the radial breathing modes (RBMs) (150-300 cm ), the D band at 1250-1450 cm the G-band at 1580 cm and the 2D band at 2500-2750 cm Each feature corresponds to different vibration modes associated with the structure of SWCNTs and will be discussed briefly below. 

Figure 9.2 shows the main spectral features of the Raman spectrum of a SWCNT, namely the radial breathing modes (RBMs) (150-300 cm ), the D... 

Raman spectroscopy was used to provide evidence of the interaction between CNTs and the PANi in the composite fibers prepared here (Figure 9). The important features of the Raman spectra for singe walled carbon nanotubes (SWNTs) (Figure 9(f)) occur in the range 200-2700 cm . The radial breathing mode (RBM) is observed in the range 170-300 cm and gives information on nanotube diameter and chirality. 

More-over the vibration analysis of MWCNTs were implemented by Aydogdu [73] using generalized shear deformation beam theory (GSD-BT). Parabolic shear deformation theory (PSDT) was used in the specific solutions and the results showed remarkable difference between PSDT and Euler beam theory and also the importance of vdW force presence for small inner radius. Lei et al. [74] have presented a theoretical vibration analysis of the radial breathing mode (RBM) of DWCNTs subjected to pressure based on elastic continuum model. It was shown that the frequency of RBM increases perspicuously as the pressure increases under different conditions. 

Gupta and Batia [77] 2008 MM3 potential Nineteen armchair, zigzag, and chiral SWCNTs have been discussed 15 Axial, torsion and radial breathing mode (RBM) vibrations of free-free unstressed SWCNTs and identifying equivalent continuum structure... 

Figure 6 Raman spectra from different types of sp -hybridized nanocarbons, which are labeled. The main features (radial breathing mode (RBM), disorder-induced D band, the first-order Raman-allowed G and, and the second-order Raman overtones G ) are identified. (Reproduced from Ref. 9. American Chemical Society, 2010.)...

Metallic and semiconducting SWCNTs have also been readily characterized by resonance Raman spectroscopy. The radial breathing mode (RBM) in the Raman spectrum of SWCNTs... 

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