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.

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.

In this article, we report the synthesis of ultra-long carbon nanotubes (CNTs) by thermal chemical vapour deposition method. Ultra-long, individual and aligned CNTs were directly grown on a flat silicon substrate. The orientation of the nanotubes was found parallel to the gas flow direction. The ultra-long CNTs were grown with different transition metallic salts, such as nickel chloride, iron (III) chloride, cobalt acetate and ruthenium acetate, as the catalysts. The influence of the growth conditions, such as growth temperature, reactive gas flow on the length and alignment of the CNTs was studied in detail. By using different catalysts, ultra-long single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) were successfully grown. These ultra-long CNTs were transferred to other substrates by two methods. (1) The first method is to use polydimethylsiloxane as a stamp. (2) The second method is to use KOH as an etching agent. The diameter and length of the CNTs were characterised by transmission electron microscope, scanning electron microscope, atomic force microscope and Raman spectroscopy. The results indicate that the length of the CNTs can reach up to 4 mm. The diameter of the SWCNTs is in the range of 0.7-2.1 nm and the diameter of the MWCNTs is approximately 150 nm.

abstract

La spectroscopie Raman est un outil de choix pour l’étude des nanomatériaux à base de carbone. Parmi ceux-ci, les nanotubes de carbone monofeuillets (CNTs) sont des structures unidimensionnelles qui peuvent être vus comme le repliement d’une feuille de graphène sur elle-même. La longueur et la direction selon laquelle le nanotube est enroulé en défini la structure. Pour cette raison, les CNTs sont identifiés par leur pseudo-vecteur chiral (ou pseudo-vecteur d’enroulement) qui est défini par un couple d’entier : n et m. La spectroscopie Raman a été largement utilisée pour obtenir des informations structurales (phonons, indices (n,m)) et sur les propriétés électroniques des CNTs. Nous avons développé une approche où le même NTC individuel, isolé et suspendu est étudié par microscopie électronique en transmission, micro-spectroscopie Raman et diffraction électronique. Nous avons ainsi pu relier la réponse Raman des NTCs (modes radiaux, modes tangentiels et transitions optiques) avec leur structure (n,m) via des mesures indépendantes. Ces résultats seront discutés et comparés aux prédictions théoriques. A partir des données obtenues, nous avons été à même de définir des critères pour l’identification des NTCs à partir de leur seule signature Raman. Ces critères, leur efficacité et leurs limites seront également présentés et discutés.