Double wall carbon nanotubes were prepared by vacuum annealing of single wall carbon nanotubes filled with C60. Strong evidence is provided for a highly defect free and unperturbed environment in the ...interior of the tubes. This is concluded from unusual narrow Raman lines for the radial breathing mode of the inner tubes. Lorentzian linewidths scale down to 0.35 cm(-1) which is almost 10 times smaller than linewidths reported so far for this mode. A splitting is observed for the majority of the Raman lines. It is considered to originate from tube-tube interaction between one inner tube and several different outer tubes. The highest RBM frequency detected is 484 cm(-1) corresponding to a tube diameter of only 0.50 nm. Labeling of the Raman lines with the folding vector is provided for all inner tubes. This labeling is supported by density functional calculations.
The functionalization of single wall carbon nanotubes (SWCNTs) is a very actively discussed topic in contemporary nanotube literature because the planned modification of SWCNT properties is believed ...to open the road towards real nanotechnology applications. In this contribution, some recent results are reported on the subject. Covalent attachment of functional groups, their influence on tube-tube stacking, detachment of functional groups, selective n- and p-type intercalation as well as special reactions carried out in the interior of SWCNTs are discussed. Clean room conditions for interior of single wall carbon nanotubes is demonstrated.
The synthesis of a unique isotope engineered system, double-wall carbon nanotubes with natural carbon outer and highly 13C enriched inner walls, is reported from isotope enriched fullerenes ...encapsulated in single-wall carbon nanotubes (SWCNTs). The material allows the observation of the D line of the highly defect-free inner tubes that can be related to a curvature induced enhancement of the electron-phonon coupling. Ab initio calculations explain the inhomogeneous broadening of inner tube Raman modes due to the distribution of different isotopes. Nuclear magnetic resonance shows a significant contrast of the isotope enriched inner SWCNTs compared to other carbon phases and provides a macroscopic measure of the inner tube mass content. The high curvature of the small diameter inner tubes manifests in an increased distribution of the chemical shift tensor components.
Single-wall carbon nanotubes (SWNTs) were oxidatively functionalized by nitric acid treatment. The presence of carboxyl groups was proven by IR spectroscopy, matching earlier IR and NMR observations. ...Raman spectra in the radial breathing mode (RBM) and G line spectral windows were measured with six laser lines ranging from 457 to 647 nm. The RBM mode was observed to upshift by the functionalization with very little change in the spectral line shape. By the analysis of the spectral moments of the lines, this upshift is interpreted as a change in an empirical intertube interaction function. In agreement with previous TEM results, we have found that bundles in a pristine SWNT sample are significantly thinner (<10 tubes) than those in the oxidized samples (>30 tubes). Changes observed in solvatation properties and sample morphology could be explained on this basis. Our observations suggest that carboxyl related secondary bonding forces might also play a role in the stacking of oxidized SWNTs.
Physics and Chemistry Inside Nanotubes Kuzmany, H.; Pfeiffer, R.; Simon, F. ...
Fullerenes, nanotubes, and carbon nanostructures,
20/4/1/, Letnik:
13, Številka:
sup1
Journal Article
Recenzirano
The interior of single-wall carbon nanotubes (SWCNTs) is investigated by filling it with fullerenes and PbO. In the former case, maximum filling concentrations are evaluated for various fullerenes as ...a function of tube diameter. For filling with C
60
a calibration table is provided that allows the determination of the filling concentration from Raman experiments. Smart filling from solution, from isotope-labeled fullerenes, and filling from nonfullerenic carbon sources is discussed. In the case of filling with PbO, an influence of lateral confinement on the phonon wave functions, an instability of the tubes versus laser irradiation, and the persistent formation of PbO nano-wires are observed.
Eur. Phys. J. B 42, 345 (2004) A detailed investigation of the Raman response of the inner tube radial
breathing modes (RBMs) in double-wall carbon nanotubes is reported. It revealed
that the number ...of observed RBMs is two to three times larger than the number
of possible tubes in the studied frequency range. This unexpected increase in
Raman lines is attributed to a splitting of the inner tube response. It is
shown to originate from the possibility that one type of inner tube may form in
different types of outer tubes and the fact that the inner tube RBM frequency
depends on the diameter of the enclosing tube. Finally, a comparison of the
inner tube RBMs and the RBMs of tubes in bundles gave clear evidence that the
interaction in a bundle is stronger than the interaction between inner and
outer tubes.
Interaction between concentric tubes in DWCNTs Pfeiffer, R; Popov, V; Simon, F ...
The European Physical Journal B - Condensed Matter and Complex Systems,
2004, Letnik:
42, Številka:
3
Journal Article
A detailed investigation of the Raman response of the inner tube radial breathing modes (RBMs) in double-wall carbon nanotubes is reported. It revealed that the number of observed RBMs is two to ...three times larger than the number of possible tubes in the studied frequency range. This unexpected increase in Raman lines is attributed to a splitting of the inner tube response. It originates from the possibility that one type of inner tubes may form in different types of outer tubes. In this case, a splitting of lines results since the inner tube RBM frequency depends on the diameter of the outer tube. Finally, a comparison of the inner tube RBMs and the RBMs of tubes in bundles gave clear evidence for a stronger interaction between tubes in a bundle as compared to the interaction between inner and outer tubes. Copyright Springer-Verlag Berlin/Heidelberg 2004
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