Résumé:

Carbon nanotubes, seamless rolled-up graphene sheets, have attracted much attention since their discovery by Iijima. Because of their unique properties, single-walled carbon nanotubes (SWNT) are expected to bring significant breakthroughs in the electronic and mechanical engineering of materials. The controlled tuning of the electronic properties of carbon nanotubes constitutes one of the major challenges for applications of these materials. A promising way to overcome the natural mixing of semiconductor and metallic tubes is intercalation with alkali metals such as rubidium. The full understanding and control of the intercalation process constitute then the fundamental step for the development of this route. Coupled “in situ” Raman spectroscopy and conductivity measurements on rubidium intercalated SWNT were firstly carried out. Peculiar profile of the conductivity curve together with the characteristic Raman responses suggest different intercalation sites as a function of the doping rate. Ex situ EXAFS studies were then performed. Our results on saturation phase Rb-doped single-wall carbon nanotube bundles show that rubidium ions have a similar local arrangement as in saturated phases of alkali intercalated graphite. Nevertheless, ex situ investigations of such samples do not allow to derive the dependence of the local arrangement with respect to the electronic transport properties. In particular, the intercalation sites (localization of Rb ions within SWNTs bundles) as a function of the doping rate are still unknown. Then, to understand properly the intercalation process, EXAFS experiments have to be combined “in situ” to Raman and electrical measurements in order to find out the correlations between the charge transfer, the structural properties (localization of Rb ions) and the electrical conductivity. Consequently, for this aim, we have developed an experimental “in situ” intercalation chamber for multi spectroscopic analysis under vacuum (10-6 mbar). Recently, our experimental set-up has been successfully used at Soleil synchrotron on the SAMBA beamline. The first results will be discussed in details.