We report an experimental study on the confinement of oligothiophene derivatives into single-walled carbon nanotubes over a large range of diameter (from 0.68 to 1.93 nm). We evidence by means of Raman spectroscopy and transmission electron microscopy that the supramolecular organizations of the confined oligothiophenes depend on the nanocontainer size. The Raman Radial Breathing Mode frequency is shown to be monitored by both the number of confined molecules into a nanotube section and the competition between oligothiophene/oligothiophene and oligothiophene/tube wall interactions. We finally propose simple Raman criteria to characterize oligothiophene supramolecular organization at the nanoscale.

Photo-active molecules are confined into single-wall carbon nanotubes to create 1D hybrid systems with new and original opto-electronic properties. This work deals with the encapsulation of quaterthiophene derivative and phthalocyanine molecules. They display strong optical absorption in the visible range, respectively around 400 and 670 nm. Encapsulation efficiency is investigated through Transmission Electron Microscopy. The physical interactions are mainly investigated by optical spectroscopies. The Raman spectra of the oligothiophene hybrid systems exhibit a striking dependence with the excitation energy which is correlated to the optical absorption energy of the photo-active molecule. Close to the molecule resonance, the results suggest a significant photo-induced charge transfer between the photo-active molecules and the nanotubes. In addition, the resonance window of the confined molecules depends on the nanotube diameter. The Raman spectra of the phthalocyanine based systems depend on the optical resonance conditions of the encapsulated molecules and on the structural properties of the hybrid system.

1D-confinement of polyiodides inside single-wall carbon nanotubes (SWCNT) is investigated. Structural arrangement of iodine species as a function of the SWCNT diameters is studied. Evidence for long range one dimensional ordering of the iodine species is shown by X-ray and electron diffraction experiments independently of the tube diameter. The structure of the confined polyiodides is investigated by X-ray absorption spectroscopy. The confinement influences the local arrangement of the chains. Below a critical diameter Fc of 1 nm, long linear polyiodides are evidenced leading to a weaker charge transfer than for nanotube diameter above Fc. A shortening of the polyiodides is exhibited with the increase of the nanotube diameter leading to a more efficient charge transfer. This point reflects the 1D-confinement of the polyiodides inside the nanotubes.

We report on the electronic properties of Cs-intercalated single-walled carbon nanotubes (SWNTs). A detailed analysis of the C-13 and Cs-133 nuclear magnetic resonance (NMR) spectra reveals an increased metallization of the pristine SWNTs under Cs intercalation. The 'metallization' of CsxC materials where x = 0-0.144 is evidenced from the increased local electronic density of states (DOS) n(E-F) at the Fermi level of the SWNTs as determined from spin-lattice relaxation measurements. In particular, there are two distinct electronic phases called alpha and beta and the transition between these occurs around x = 0.05. The electronic DOS at the Fermi level increases monotonically at low intercalation levels x < 0.05 (alpha-phase), whereas it reaches a plateau in the range 0.05 <= x <= 0.143 at high intercalation levels (beta-phase). The new beta-phase is accompanied by a hybridization of Cs(6s) orbitals with C(sp(2)) orbitals of the SWNTs. In both phases, two types of metallic nanotubes are found with a low and a high local n(E-F), corresponding to different local electronic band structures of the SWNTs.

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.

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.

X-ray and neutron-diffraction investigations of rubidium-intercalated single-walled carbon nanotubes are reported. Ab initio calculations conducted in combination with our experiments show that for a single Rb ion the most energetically favorable intercalation site is the interstitial channel between three tubes in a bundle. At higher doping levels, as the Rb content increases, this site becomes however unfavored with respect to the interior of the tubes or the external surface of the bundle. Model simulations of the diffraction patterns, capable of well reproducing both the x-ray and neutron-diffraction patterns, indicate that only the latter insertion sites are compatible with the experimental data. Finally we show that the bundle surface site is the most probable one in the case of saturation at an estimated stoichiometry close to RbC8.