Ref HAL: hal-00496809_v1
DOI: 10.1103/PhysRevB.80.245416
WoS: 000273229200120
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50 Citations
Résumé:

From combined Raman spectroscopy and electron diffraction studies on several freestanding single-walled carbon nanotubes (SWNTs), we define Raman criteria which correlate the main features of the Raman spectrum (radial breathing mode and G modes) and the optical transition energies with the structure of the SWNT under investigation. On this basis, we discuss the possibilities to determine the (n,m) indices of an individual SWNT from a single wavelength Raman experiment. We show the efficiency of this approach in assigning the (n,m) structure of different individual nanotubes including all types of achiral SWNTs. Finally, the limits and the accuracy of the method are discussed.

Ref HAL: hal-00496808_v1
DOI: 10.1103/PhysRevB.79.195417
WoS: 000266501300116
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27 Citations
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The Raman spectral signature of folded graphene layers for one to six layers was studied. Folding allows realization of rotational disorder in otherwise perfect samples. We show that the two-dimensional Raman band of the folded sample is up shifted compared to the unfolded sample. The evolution of the spectral signature with increasing number of layers is discussed.

Ref HAL: hal-00496519_v1
DOI: 10.1103/PhysRevB.79.237402
WoS: 000267699500153
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5 Citations
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In their Comment, Ni et al. show new data as supporting their hypothesis, i. e., the two-dimensional band blueshift between graphene and misoriented bilayer is caused by a reduction in the Fermi velocity. In the first part of our reply, we will demonstrate that the exhibited data, which typically shows a constant blueshift for various excitation energies are in contradiction with a change in Fermi velocity. In the second part we will explain how charge transfer from the substrate that affects the phonon-dispersion curve can account for the observed discrepancies and how this hypothesis is supported by experimental observations.

DOI: 10.1063/1.3223326
WoS: 000270378100046
8 Citations
Résumé:

Fourier transformed infrared microreflectance spectroscopy is used to probe and compare the consequences of thermal quenching or ionic implantation on the structure of silica. A linear change in the main structural feature associated with Si-O-Si vibration with fictive temperature (T-f) is observed up to T-f = 1400 degrees C. Ionic implantation is shown to shift the frequency of the main IR Si-O-Si vibration toward much lower wavenumbers, for all deposited energies, indicating that a comparison can be drawn between fictive temperature and irradiation effects. Extrapolating the linear changes in the IR structural bands obtained as a function of T-f for the implanted samples, we show that two structural (nu(TO)) and (nu(B)) contributions are not affected by ionic implantation, as they would be by a unique very high T-f. In the case of ionic implantation, we also evidence the development of some specific structural contributions indicating a depolymerization of silica network. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3223326]

Ref HAL: hal-00276997_v1
Ref Arxiv: 0805.0511
DOI: 10.1103/PhysRevB.78.113407
WoS: 000259690800025
Ref. & Cit.: NASA ADS
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187 Citations
Résumé:

We compare the main feature of the measured Raman scattering spectra from single layer graphene with a bilayer in which the two layers are arbitrarily misoriented. The profiles of the 2D bands are very similar having only one component, contrary to the four found for commensurate Bernal bilayers. These results agree with recent theoretical calculations and point to the similarity of the electronic structures of single layer graphene and misoriented bilayer graphene. Another new aspect is that the dependance of the 2D frequency on the laser excitation energy is different in these two latter systems.

Ref HAL: hal-00496385_v1
PMID 18540661
DOI: 10.1021/nl0803141
WoS: 000257504500009
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75 Citations
Résumé:

Adsorption of specifically designed and geometrically constrained polyaromatic amphiphiles on single-walled carbon nanotubes (SWNTs) was found to be selective of the nanotube helicity angle. Starting from the same SWNT mixture, photoluminescence and resonant Raman spectroscopies show that a pentacenic-based amphiphile leads to the solubilization of armchair SWNTs and that a quaterrylene-based amphiphile leads to the solubilization of zigzag SWNTs. The results were predicted by the design of the two amphiphiles and are consistent with a supramolecular recognition of the nanotube graphene-type atomic structure by the aromatic part of the molecules through optimized pi-pi(-) stacking interactions.

DOI: 10.1346/CCMN.2008.0560406
WoS: 000259664600006
10 Citations