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Structural selective charge transfer in iodine-doped carbon nanotubes
Auteur(s): Michel T., Alvarez L., Sauvajol J.-L., Almairac Robert, Aznar R., Mathon O., Bantignies J.-L., Flahaut Emmanuel
(Article) Publié:
Journal Of Physics And Chemistry Of Solids, vol. vol. 67 n° 5-6. p.1190-1192 , available on http://oatao.univ-toulouse.fr/744/1/flahaut_744.pdf (2006)
Ref HAL: hal-00474864_v1
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Résumé: We have investigated iodine intercalated carbon nanostructures by extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies. We discuss here the charge transfer and the iodine–carbon interaction as a function of the carbon nanostructures (graphite, multi-walled, double-walled and single walled nanotubes). The results show that iodine is weakly adsorbed on the surface of all multi-walled nanotubes. By contrast, a charge transfer between iodine and single walled nanotubes is evidenced.
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EXAFS investigations of iodine-doped carbon nanotubes
Auteur(s): Michel T., Alvarez L., Sauvajol J.-L., Almairac Robert, Aznar R., Bantignies J.-L., Mathon O.
(Article) Publié:
Physical Review B, vol. 73 p.195419 (2006)
Ref HAL: hal-00498071_v1
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Résumé: We report an x-ray absorption fine structure study at the iodine-K edge of the local structure in iodine-doped carbon nanotubes. The iodine-carbon host interaction is shown to be weaker in multiwalled carbon nanotubes (MWNTs) than in single-walled carbon nanotubes (SWNTs). Iodine species are only localized at the surface of the external tube for MWNTs, whereas iodine species enter inside SWNTs. For doped SWNTs, both the experimental and the theoretical EXAFS spectra allow us to establish the structure of the iodine chain as disordered pentaiodide at the saturation level.
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Dynamics charge tensors and infrared spectra of the crystalline quaterthiophene polymorph phases from first-principles calculations.
Auteur(s): Hermet P., Bantignies J.-L., Sauvajol J.-L., Johnson M.
(Article) Publié:
Synthetic Metals, vol. 156 p.519-524 (2006)
Texte intégral en Openaccess :
Ref HAL: hal-00514939_v1
DOI: 10.1016/j.synthmet.2005.11.003
WoS: 000238158700005
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8 Citations
Résumé: Infrared intramolecular vibrations and lattice modes for both the crystalline α-quaterthiophene (4T) polymorph phases are investigated by using the modern theory of polarization combined with density functional theory. For the first time, Born effective charge tensors and far- and mid-infrared responses for both the polymorph phases of 4T have been calculated. We have also proposed an assignment of the main spectral infrared signatures of the 4T polymorph phases. These assignments could be of particular interest in the far-infrared domain for the understanding of the electronic transport of these materials.
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Insights into the Self-Directed Structuring of Hybrid Organic-Inorganic Silicas through Infrared Studies
Auteur(s): Bantignies J.-L., Vellutini Luc, Maurin D., Hermet P., Dieudonne-George P., Wong Chi Man Michel, R. Bartlett John, Bied Catherine, Sauvajol J.-L., J. E. Moreau Joël
(Article) Publié:
The Journal Of Physical Chemistry B, vol. 110 p.15797 -15802 (2006)
Texte intégral en Openaccess :
Ref HAL: hal-00163295_v1
PMID 16898728
DOI: 10.1021/jp060975r
WoS: 000239656100026
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44 Citations
Résumé: Fourier transform infrared (FTIR) spectroscopy has been used to probe the organization of the organic fragments in lamellar bridged silsesquioxanes with organic substructures based on alkylene chains of various lengths and urea groups [O1.5Si(CH2)3NHCONH(CH2)nNHCONH(CH2)3SiO1.5] (n = 6, 8-12). The structure and intermolecular interactions (hydrophobic and H-bonding) of these well-defined self-structured hybrid silicas are discussed in relation to their powder X-ray diffraction patterns. The degree of structural order is determined by the length and parity of the alkylene spacer. A concomitant enhancement in the degree of condensation of the inorganic component and a decrease in the strength of the hydrophobic interactions between the organic components are demonstrated. The strength and directionality of the H-bonding are directly correlated to the crystalllinity of the organic-inorganic hybrid materials.
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Infrared-active phonons in carbon nanotubes
Auteur(s): Bantignies J.-L., Sauvajol J.-L., Rahmani A., Flahaut E.
(Article) Publié:
Physical Review B, vol. 74 p.195425-1-5 (2006)
Texte intégral en Openaccess :
Ref HAL: hal-00514943_v1
DOI: 10.1103/PhysRevB.74.195425
WoS: 000242409200143
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40 Citations
Résumé: The aim of the present paper is to identify the main infrared vibrational features of carbon nanotubes. In this goal, infrared experiments have been performed on different well-characterized single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) as well as graphite and carbon aerogel. The comparison between the experimental spectra measured on these different samples allows us to identify the infrared-active modes of carbon nanotubes. In SWCNTs, the tangential modes are located around 1590 cm−1 and the radial mode around 860 cm−1. This latter mode vanishes in the infrared spectrum of DWCNTs. Finally, in the infrared spectra of all the carbon nanotubes investigated, a band around 1200 cm−1 is evidenced and assigned to the D-band (disorder-induced band).
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Lamellar Bridged Silsesquioxanes: Self-Assembly through a Combination of Hydrogen Bonding and Hydrophobic Interactions
Auteur(s): J. E. Moreau Joël, Vellutini Luc, Wong Chi Man Michel, Bied Catherine, Dieudonne-George P., Bantignies J.-L., Sauvajol J.-L.
(Article) Publié:
Chemistry - A European Journal, vol. 11 p.1527-1537 (2005)
Texte intégral en Openaccess :
Ref HAL: hal-00163480_v1
PMID 15662678
DOI: 10.1002/chem.200401012
WoS: 000227262000017
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97 Citations
Résumé: The synthesis of four bis(trialkoxysilylated) organic molecules capable of self-assembly - (EtO)3Si(CH2)3NHCONH(CH2)nNHCONH(CH2)3Si(OEt)3 (n = 9-12) - associating urea functional groups and alkylidene chains of variable length is described. These compounds behave as organogelators, forming supramolecular assemblies thanks to the intermolecular hydrogen bonding of urea groups. Whereas fluoride ion-catalysed hydrolysis in ethanol in the presence of a stoichiometric amount of water produced amorphous hybrids, acid-catalysed hydrolysis in an excess of water gave rise to the formation of crystalline lamellar hybrid materials through a self-organisation process. The structural features of these nanostructured organic/inorganic hybrids were analysed by several techniques: attenuated Fourier transformed infrared (ATR-FTIR), solid-state NMR spectroscopy (13C and 29Si), scanning and transmission electron microscopy (SEM and TEM) and powder X-ray diffraction (PXRD). The reaction conditions, the hydrophobic properties of the long alkylidene chains and the hydrogen-bonding properties of the urea groups are determining factors in the formation of these self-assembled nanostructured hybrid silicas.
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Structural ordering of self-assembled alkylene-bridged silsesquioxanes probed by X-ray diffraction experiments
Auteur(s): J. E. Moreau Joël, Vellutini Luc, Dieudonne-George P., Wong Chi Man Michel, Bantignies J.-L., Sauvajol J.-L., Bied Catherine
(Article) Publié:
Journal Of Materials Chemistry, vol. 15 p.4943-4948 (2005)
Texte intégral en Openaccess :
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