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Investigation on the vibrational and structural properties of a self-structured bridged silsesquioxane
Auteur(s): Greff Gaëlle, Arrachart Guilhem, Hermet P., Wadepohl Hubert, Almairac Robert, Maurin D., Sauvajol J.-L., Carcel Carole, Moreau Joël J.E., Dieudonne-George P., Wong Chi Man Michel, Bantignies J.-L.
(Article) Publié:
Physical Chemistry Chemical Physics, vol. 14 p.5672-5679 (2012)
Ref HAL: hal-00683723_v1
PMID 22422291
DOI: 10.1039/c2cp40250e
WoS: 000302062200038
Exporter : BibTex | endNote
18 Citations
Résumé: The crystalline structure of ureidopyrimidinone-based silane (UPY) has been determined. The local and long range order structuring of the bridged silsesquioxane (MUPY) resulting from the sol-gel hydrolysis-condensation of the former precursor has been investigated by MFTIR (Mid Fourier Transform InfraRed) combined with DFT (Density Functional Theory) and XRD (X-ray diffraction) studies. These studies showed that a long range structuring exists within the organic fragments with the transcription of the DDAA (Donor-Donor-Acceptor-Acceptor) H-bonding array from UPY to MUPY whereas a disordered siloxane network was revealed in the hybrid material.
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Charge transfer in conjugated oligomers encapsulated into carbon nanotubes
Auteur(s): Almadori Y., Alvarez L., Arenal Raul, Babaa Moulay-Rachid, Michel T., Le Parc R., Bantignies J.-L., Jousselme Bruno, Palacin Serge, Hermet P., Sauvajol J.-L.
(Article) Publié:
Physica Status Solidi B, vol. 148 p.2560-2563 (2011)
Texte intégral en Openaccess :
Ref HAL: cea-00960689_v1
DOI: 10.1002/pssb.201100094
WoS: 000297517100031
Exporter : BibTex | endNote
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.
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Charge Transfer Evidence between Carbon Nanotubes and Encapsulated Conjugated Oligomers
Auteur(s): Alvarez L., Almadori Y., Arenal Raul, Babaa Moulay-Rachid, Michel T., Le Parc R., Bantignies J.-L., Jousselme Bruno, Palacin Serge, Hermet P., Sauvajol J.-L.
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 115 p.11898-11905 (2011)
Texte intégral en Openaccess :
Ref HAL: cea-00960683_v1
DOI: 10.1021/jp1121678
WoS: 000291709600002
Exporter : BibTex | endNote
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
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Time-Resolved Investigation of Excitation Energy Transfer in Carbon Nanotube-Porphyrin Compounds
Auteur(s): Garrot Damien, Langlois Benjamin, Roquelet Cyrielle, Michel T., Roussignol Philippe, Delalande Claude, Deleporte Emmanuelle, Lauret Jean‐sébastien, Voisin Christophe
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 115 p.23283 (2011)
Ref HAL: hal-00661217_v1
DOI: 10.1021/jp207267e
WoS: 000297195200006
Exporter : BibTex | endNote
28 Citations
Résumé: Single-wall carbon nanotubes non-covalently functionalized with porphyrin molecules have proven to be a very promising light harvesting system either for energy or charge transfer. In this paper we investigate the dynamics of this coupling at a sub-picosecond time-scale, by means of transient absorption spectroscopy. We show that the ground state recovery time of the porphyrin is reduced by several orders of magnitude in the compound compared to the case of pristine porphyrin. Concomitantly, a strong bleaching signal is observed on the optical resonances of the nanotubes showing an ultrafast population buildup upon excitation of the porphyrin. We conclude that the energy transfer occurs on a time-scale shorter than 100 fs. Two-color measurements show that higher excited states of the nanotubes are populated on the same time-scale raising the point of the transfer mechanism. We briefly discuss two possible mechanisms.
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Characterization and boron adsorption of hydrothermally synthesised allophanes
Auteur(s): Reinert Laurence, Ohashi Fumihiko, Kehal Mohamed, Bantignies J.-L., Goze-Bac C., Duclaux Laurent
(Article) Publié:
Applied Clay Science, vol. 54 p.274-280 (2011)
DOI: 10.1016/j.clay.2011.10.002
WoS: 000298513500012
15 Citations
Résumé: Two hydrothermally synthesised allophanes (Si/Al = 0.5 and 1) were modified by heating at 400 degrees C. N-methyl-D-glucamine, a specific boron complexant, was grafted on the allophane material with Si/Al = 0.5. The surface and structural properties of the different materials were characterised by infrared spectroscopy and Si-29 CP MAS NMR spectroscopy. The porous characteristics of the different allophanes (specific surface area, pore size distribution) were determined by nitrogen adsorption at 77 K using the BET equation and the BJH model. The adsorption of boron, i.e. boric acid/borate, by the modified allophanes was studied in aqueous solutions with boron contents of 1 to 100 mg L-1. The pH-dependence of boron adsorption of all the sorbents showed a maximum at a pH value close to the pKa value of boric acid (pKa H3BO3/B (OH)(4)(-) = 9.26). The adsorption isotherms of boron by raw and modified allophanes were fitted with a double Langmuir equation, assuming the presence of two sets of adsorption sites. The grafting of N-methyl-D-glucamine did not improve the boron adsorption of the allophanes but the structural changes by heating at 400 degrees C increased the adsorption. (C) 2011 Elsevier B.V. All rights reserved.
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Dielectric, magnetic, and phonon properties of nickel hydroxide
Auteur(s): Hermet P., Gourrier L., Bantignies J.-L., Ravot D., Michel T., Deabate S., Boulet P., Henn F.
(Article) Publié:
-Physical Review B Condensed Matter And Materials Physics (1998-2015), vol. 84 p.235211 (2011)
DOI: 10.1103/PhysRevB.84.235211
WoS: 000298559600011
87 Citations
Résumé: We carried out a complete study (magnetic, electronic, dielectric, dynamic, and elastic properties) of the nickel hydroxide [Ni(OH)2] from first-principles calculations based on density functional theory. No theoretical investigations of these physical properties have been previously reported in literature. Our work supports that Ni(OH)2 is an A-type antiferromagnetic material. In addition, it is negative uniaxial and semiconducting with a direct band gap at the Γ point around 3 eV. By contrast to its electronic dielectric tensor, its static tensor is strongly anisotropic in the plane orthogonal to its optical axis. This anisotropy is mainly governed by a highly polar phonon centered around 510 cm−1 and assigned as a rotational Eu mode. Both Raman and infrared spectra have been computed to clarify the longstanding debate on the assignment of the Ni(OH)2 phonon modes reported in literature. All these theoretical results are fruitfully compared to the experimental ones obtained on large Ni(OH)2 "pseudosingle" crystals when available.
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High-pressure behavior of polyiodides confined into single-walled carbon nanotubes: A Raman study
Auteur(s): Alvarez L., Bantignies J.-L., Le Parc R., Aznar R., Sauvajol J.-L., Merlen Alexandre, Machon D., San Miguel A.
(Article) Publié:
Physical Review B, vol. 82 p.205403 (2010)
Ref HAL: hal-00534900_v1
DOI: 10.1103/PhysRevB.82.205403
WoS: 000283840100010
Exporter : BibTex | endNote
57 Citations
Résumé: The high-pressure behavior of polyiodides confined into the hollow core of single-walled carbon nanotubes organized into bundles has been studied by means of Raman spectroscopy. Several regimes of the structural properties are observed for the nanotubes and the polyiodides under pressure. Raman responses of both compounds exhibit correlations over the whole pressure range (0–17 GPa). Modifications, in particular, take place, respectively, between 1 and 2.3 GPa for polyiodides and between 7 and 9 GPa for nanotubes, depending on the experiment. Differences between one experiment to another are discussed in terms of nanotube filling homogeneity. These transitions can be presumably assigned to the tube ovalization pressure and to the tube collapse pressure. A nonreversibility of several polyiodide mode modifications is evidenced and interpreted in terms of a progressive linearization of the iodine polyanions and a reduction in the charged species on pressure release. Furthermore, the significant change in the mode intensities could be associated to an enhancement of lattice modes, suggesting the formation of a new structure inside the nanotube. Changes in the nanotube mode positions after pressure release point out a decrease in the charge transfer in the hybrid system consistent with the observed evolution of the charged species.
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