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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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In situ X-ray Absorption Spectroscopy Study of Si(1-x)GexO2 Dissolution and Germanium Speciation under Hydrothermal Conditions
Auteur(s): Ranieri Vincent, Haines Julien, Cambon Olivier, Levelut C., Le Parc R., Cambon Martine, Hazemann Jean-Louis
(Article) Publié:
Inorganic Chemistry, vol. 51 p.414-419 (2012)
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n-type doping of carbon nanotubes by encapsulation of conjugated oligomers
Auteur(s): Almadori Y., Alvarez L., Arenal Raul, Babaa Rachid, Michel T., Le Parc R., Bantignies J.-L., Jousselme Bruno, Palacin Serge, Hermet P., Sauvajol J.-L.
(Affiches/Poster)
Dourdan, GDR (Dourdan, FR), 2011-02-08Texte intégral en Openaccess :
Résumé: The Hybrid system consisting in quaterthiophene derivative inserted into single and multi-walled
carbon nanotubes is studied. Encapsulation efficiency of the conjugated oligomers in the hollow core of
nanotube is investigated by Transmission Electron Microscopy and spatial resolved electron energy loss
spectroscopy. We clearly show from Raman spectroscopy that the interaction between nanotubes and oligomers
deeply depends on the metallic or semiconducting character of nanotubes. The charge transfer is shown to be
significantly stronger for semiconducting tubes than for metallic ones. In addition, the shift of the Raman-active
G band together and the appearance of a new peak in the 2D band of the semiconducting nanotubes state a ntype
doping of the nanotubes. Complementary, the infrared spectra evidence a p-type doping of the oligomer.
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Pressure-induced structural transitions in phase-change materials based on Ge-free Sb-Te alloys
Auteur(s): Krbal Milos, Kolobov Alexander V., Fons P., Haines Julien, Pradel Annie, Ribes Michel, Piarristeguy Andrea, Levelut C., Le Parc R., Agafonov V., Hanfland M., Tominaga J.
(Article) Publié:
Physical Review B, vol. 83 p.024105 (2011)
Ref HAL: hal-00564141_v1
DOI: 10.1103/PhysRevB.83.024105
WoS: 000286753400002
Exporter : BibTex | endNote
12 Citations
Résumé: We report on pressure-induced phase transitions in the Sb2Te and Ag11In6Sb55Te28 (AIST) phase change alloys used in optical recording media over a pressure range from ambient pressure to 40 GPa. The results clearly demonstrate the crucial role of dopants in sequences of high-pressure structural transformations and in the degree of reversion.We also demonstrate that prolonged exposure of AIST to high pressures leads to an additional phase transition that may have fatal consequences for process reversibility in repeated compression/decompression cycles.
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'Vibrational Properties In Polyarene Crystals'
Auteur(s): Le Parc R., Alvarez L., Hermet P., Jourdain V., Bantignies J.-L., Sauvajol J.-L., Rose J, Scott L.t.
(Affiches/Poster)
GDR (Dourdan, FR), 2011-02-08
Résumé: Le corannulène C20H10 est une molécule en forme de coupelle composée de cycles
pentagonaux et hexagonaux appartenant à la famille des polyarènes géodésiques. Les nano-molécules
de polyarènes géodésiques peuvent s’organiser dans la formation de cristaux moléculaires. Dans le cas
du corannulène, la structure du cristal a été reportée pour la première fois en 1976, [1] comme
appartenant à au groupe d’espace monoclinique P21c puis cette structure a été récemment confirmée
[2]. Dans cette structure la cellule unité est composée de deux molécules se présentant dans deux
orientations différentes de manière inclinée par rapport à l’axe de symétrie de la molécule.
Quelques travaux reportent l’étude du corannulène par spectroscopie vibrationnelle, mais la plupart de
ces travaux sont bases sur des simulations [3,4]. Les spectroscopies vibrationnelles s’avèrent être des
outils très intéressants pour étudier de telles molécules. En effet, de part leur courbure, les polyarènes
géodésiques sont très différentes des molécules planes ou des cages rigides : la nature des liaisons est
très différente. Par ailleurs, les interactions avec l’environnement peuvent entraîner une distorsion de
la molécule et donc une brisure de symétrie donnant ainsi naissance à des modes de vibration
auparavant interdits.
Dans ce travail, nous nous sommes intéressés à l’influence de la température et de la pression sur les
modes de vibration des molécules de corannulène, comment ces modes évoluent-ils ? voit-on
apparaître de nouveaux modes? La spectroscopie vibrationnelle est également très sensible à la
structure des cristaux moléculaires notamment au travers des modes Raman basses fréquences.
Comment cette structure évolue-t-elle avec la température et la pression ? Quelles sont les interactions
entre les molécules dans ces cristaux et comment évoluent-elles ? Nous montrerons que les outils
spectroscopiques apportent déjà des premières réponses à ces questions.
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HIGH PRESSURE BEHAVIOUR 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, San miguel Alfonso, Machon Denis
Conference: Groupement de Recherche "Graphène et Nanotubes" Science et Applications (Dourdan, FR, 2011-02-07)
Résumé: The high pressure behaviour 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 at the tube collapse pressure. A non reversibility of several polyiodide mode modifications is evidenced and interpreted in terms of a progressive linearization of the iodine polyanions and a reduction of the charged species on pressure release. Furthermore, the significant change of the mode intensities could be associated to an enhancement of lattice modes, suggesting the formation of a new structure inside the nanotube. Changes of the nanotube mode positions after pressure release features point out a decrease of the charge transfer in the hybrid system consistent with the observed evolution of the charged species.
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n-type doping of carbon nanotubes by encapsulation of conjugated oligomers
Auteur(s): Alvarez L., Almadori Y., Bantignies J.-L., Michel T., Hermet P., Le Parc R., Sauvajol J.-L., Babaa Rachid, Jousselme Bruno, Palacin Serge, Arenal Raul
Conference: 25th International Winterschool on Electronic Properties of Novel Materials (IWEPNM) (Kirchberg, AT, 2011-02-26)
Résumé: Hybrid system consisting in quaterthiophene derivative inserted into single and multi-walled carbon nanotubes is studied. Encapsulation efficiency of the conjugated oligomers in the hollow core of nanotube is investigated by Transmission Electron Microscopy and spatial resolved electron energy loss spectroscopy. We clearly show from Raman spectroscopy that the interaction between nanotubes and oligomers deeply depends on the metallic or semiconducting character of nanotubes. The charge transfer is shown to be significantly stronger for semiconducting tubes than for metallic ones. In addition, the shift of the Raman-active G band together with the appearance of a new peak in the 2D band of the semiconducting nanotubes state a n-type doping of the nanotubes. Complementary, the infrared spectra evidence a p-type doping of the oligomer.
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