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.

Dans cet exposé, après une brève présentation de la structure et des propriétés électroniques des nanotubes de carbone, je me focaliserai sur les données de diffusion Raman obtenues sur des tubes individuels suspendus, mono-(SWNT) et bi-feuillets (DWNT), dont les structures sont parfaitement déterminées par microcopie électronique en transmission à haute résolution (HRTEM) et diffraction électronique. Les données mesurées sur des SWNTs individuels éclairent le rôle du diamètre, de la courbure, de la chiralité et du couplage électron-phonon sur les caractéristiques des phonons, L’effet des interactions électron-électron et de l’exciton sur les énergies de transition est identifié. Toutes ces données expérimentales, obtenues sur des tubes parfaitement identifiés, sont confrontées aux prédictions de modèles théoriques. Les données récentes mesurées sur des DWNTs identifiés ont, pour la première fois, permis de mettre clairement en évidence le rôle du couplage entre les feuillets sur les caractéristiques des phonons et sur leur condition d’observation.

Using the spectral moment's method, the infrared spectra of single-walled boron nitride nanotubes are calculated. The dependence of these modes has been calculated as a function of the nanotube chirality, diameter (from 0.7 to 5 nm), and length. These predictions are useful for understanding the experimental infrared spectra of boron nitride nanotubes.

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.

Merging the fields of carbon nanotubes (NTs) and of organic semiconductors opens a wide range of fundamental investigations and potential applications. We developed a two step covalent functionalization method in order to graft complex Pi-conjugated systems on NT sidewalls. In a first step, iodoaniline or iododiphenylacetylene is anchored via the diazonium reaction. Several organometallic coupling reactions, as illustrated on figure 1, have been tested as a second step. The simpliest hybrid systems obtained are illustrated on figure 1 but several other much more complex have been successfully grafted. The hybrid systems obtained have been studied by resonant Raman spectroscopy, XPS, optical absorption and photoluminescence. The impact of functionalization on the properties of both moieties will be discussed and the different chemical reactions used will be compared.

Graphite Intercalation Compounds have been the subject of intensive research. With the rise of graphene, new opportunities emerge in the field. On the one hand, adsorption and/or intercalation of hetero-atoms offer a gateway to tune graphene properties. On the other hand, investigations on a simpler system open the way towards increasing knowledge on the intercalant/host physical properties. New questions to be addressed also arise, such as, what happens when the number of layers is reduced? We have developed a setup derived from the two zone vapor transport method used to produce graphite intercalation compounds. It allows performing in situ Raman experiments during graphene doping by alkali vapor. The results obtained on the evolutions of the G and 2D bands during rubidium doping of graphene and bilayer graphene will be presented and discussed.

Raman results obtained on graphene edges will be presented. In a first study, the variation of the relative intensity of the D and G band as a function of the graphene ribbon width was investigated. In a second one, we developed an hyperspectral Raman method in order to determine the evolution of the ID/IG ratio as a function of excitation wavelength. Our results will be discussed in regards with published data on graphite nanocristallites and more recently on graphene.