Ref HAL: hal-00808165_v1
DOI: 10.1016/j.carbon.2012.09.010
WoS: 000314192700012
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18 Citations
Résumé:

1D-confinement of polyiodides inside single-wall carbon nanotubes (SWCNT) is investigated. Structural arrangement of iodine species as a function of the SWCNT diameters is studied. Evidence for long range one dimensional ordering of the iodine species is shown by X-ray and electron diffraction experiments independently of the tube diameter. The structure of the confined polyiodides is investigated by X-ray absorption spectroscopy. The confinement influences the local arrangement of the chains. Below a critical diameter Fc of 1 nm, long linear polyiodides are evidenced leading to a weaker charge transfer than for nanotube diameter above Fc. A shortening of the polyiodides is exhibited with the increase of the nanotube diameter leading to a more efficient charge transfer. This point reflects the 1D-confinement of the polyiodides inside the nanotubes.

Ref HAL: hal-00811653_v1
DOI: 10.1021/jp307536d
WoS: 000311650400029
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11 Citations
Résumé:

Vibrational dynamics in the corannulene crystal is exhaustively studied through Raman scattering, infrared spectroscopy, and inelastic neutron scattering. Experimental data are coupled to simulations of the phonon modes performed in the framework of first principle calculations. Intermolecular vibrations (libration and translation) are assigned in the low frequency domain (10-200 cm-1). These modes exhibit specific temperature dependence in the far-infrared.

Ref HAL: hal-00718101_v1
DOI: 10.1166/jno.2012.1221
WoS: 000303279800016
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1 Citation
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We report the temperature dependence of the Raman spectra of a gelatine-based composite material doped with single-walled carbon nanotubes (SWNT@gelatin). On decreasing the temperature from 290 to 20 K a significant up-shift of the G-mode and no changes in the radial breathing modes are observed. This behaviour cannot be understood by pure thermal effects. We explain these results in terms of an uniaxial strain of the nanotubes induced by the thermal expansion mismatch between the nanotubes and the surrounding matrix.

Résumé:

Photo-active molecules are confined into single-wall carbon nanotubes to create 1D hybrid systems with new and original opto-electronic properties. This work deals with the encapsulation of oligothiophene and phtalocyanine molecules displaying strong optical absorption in the visible range, respectively around 400 and 670 nm. Encapsulation efficiency is investigated by Transmission Electron Microscopy and spatial resolved Electron Energy Loss Spectroscopy. The physical interaction is mainly investigated by optical spectroscopies. Raman spectra of the hybrid systems exhibit a striking dependence with the excitation energy which is correlated to the optical absorption energy of the photo-active molecule [1,2]. Close to the molecule resonance, the G-band can shift and the Radial Breathing Mode intensities strongly decrease, which suggest a significant photo-induced charge transfer between the photo-active molecules and the nanotubes.

Ref HAL: hal-00711335_v3
Ref Arxiv: 1206.5464
DOI: 10.1016/j.carbon.2012.06.007
WoS: 000308898900001
Ref. & Cit.: NASA ADS
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31 Citations
Résumé:

A spectroscopic study of the amino functionalization of double-walled carbon nanotube (DWCNT) is performed. Original experimental investigations by near edge X-ray absorption fine structure spectroscopy at the C and O K-edges allow one to follow the efficiency of the chemistry during the different steps of covalent functionalization. Combined with Raman spectroscopy, the characterization gives a direct evidence of the grafting of amino-terminated molecules on the structural defects of the DWCNT external wall, whereas the internal wall does not undergo any change. Structural and mechanical investigation of the amino functionalized DWCNT / epoxy composites show coupling between epoxy molecules and the DWCNTs. Functionalization improves the interface between amino-functionalized DWCNT and the epoxy molecules. The electrical transport measurements indicate a percolating network formed only by inner metallic tubes of the DWCNTs. The activation energy of the barriers between connected metallic tubes is determined around 20 meV.

Ref HAL: cea-00960689_v1
DOI: 10.1002/pssb.201100094
WoS: 000297517100031
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5 Citations
Résumé:

This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer.

Ref HAL: cea-00960683_v1
DOI: 10.1021/jp1121678
WoS: 000291709600002
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41 Citations
Résumé:

A hybrid system consisting of quaterthiophene derivative inserted into carbon nanotubes is studied. Encapsulation efficiency of the conjugated oligomers in the hollow core of nanotubes is investigated by transmission electron microscopy and spatial-resolved electron energy loss spectroscopy. Infrared spectroscopy showed evidence of a significant positive charge transfer on the inserted oligothiophene. Raman spectra display different behaviors depending on the excitation energy and correlated to the quaterthiophene optical absorption energy. At high excitation wavelength (far from the oligomer resonance), radial breathing modes exhibit a significant upshift consistent with an encapsulation effect. At low excitation wavelength (close to the oligomer resonance), both the G-band shift and the low-frequency modes vanishing suggest a significant charge transfer between the quaterthiophene and the nanotubes