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We present a Raman spectroscopy study of iodine-intercalated (p-type doped) double-walled carbon nanotubes. Double-walled carbon nanotubes (DWCNTs) are synthesized by catalytic chemical vapor deposition (CCVD) and characterized by Raman spectroscopy. The assignment of the radial breathing modes and the tangential modes of pristine DWCNTs is done in the framework of the bond polarization theory, using the spectral moment method. The changes in the Raman spectrum upon iodine doping are analysed. Poly-iodine anions are identified, and the Raman spectra reveal that the charge transfer between iodine and DWCNTs only involves the outer tubes.

International audienceNew one-dimensional (1D) hybrid nanosystems are elaborated withmetalated or metal free phthalocyanine molecules encapsulated into the hollow core ofsingle-walled carbon nanotubes. The X-ray diffraction experiments coupled to simulationallow evidencing the 1D structural organization of the molecules inside the nanotubes. Theangle between the molecule ring and the nanotube axis is close to 32° as determined fromour density functional theory calculations. Confined molecules display Raman spectrahardly altered with respect to the bulk phase, suggesting a rather weak interaction with thetubes. For comparison, noncovalent functionalization at the outer surface of the tube is also investigated. The vibrationalproperties of the molecules functionalized at the outer surface of tubes display important modifications. A significant curvature ofthe phthalocyanine is induced by the interaction with the tube walls, leading to change of the central atom position within themolecular ring, in good agreement with our first-principles calculations

Combining high resolution transmission electron spectroscopy, electron diffraction, and resonant Raman spectroscopy experiments on the same suspended (free-standing) individual carbon nanotubes is the ultimate approach to relate unambiguously the structure and the intrinsic phonon features of these nano-systems.By using this approach, the effect of coupling between nanotubes on the phonons is investigated in two model nano-systems: (i) a bundle of two non-identical SWNTs (inhomogeneous dimer), (ii) double-walled carbon nanotubes.

International audienceInfrared response on a carbon nanotube is weak because this homonuclear allotrope of carbon does not bear permanent dipoles. Here, we report the discovery of an exaltation of the infrared absorption response in single-walled carbon nanotubes from dye molecule interactions. A study performed on dimethylquaterthiophene confined into the hollow core of single-walled carbon nanotubes or π-stacked at the outer surface of the latter leads to a symmetry breaking, allowing us to probe interactions between both subsystems. The nature of these interactions is discussed taking into account the tube diameter. This new phenomenon opens a new route to detect weak vibrations thanks to a confinement effect

Encapsulation of photoactive organic molecules inside single‐walled carbon nanotubes (SWNTs) appears to be of great interest in terms of high power conversion efficiency and long‐term stability for a commercial application of organic solar cells (OSCs). In this paper, we report a charge transfer (CT) evidence in donor–acceptor SWNTs filled with Sexithiophene oligomers (6T) by Raman spectroscopy. To compute the optimal diameter and demonstrate the most stable structure of the hybrid systems with either a single 6T molecule encapsulated into SWNTs (6T@SWNTs), or two 6T chains encapsulated (6T‐6T@SWNTs), we have performed structural geometry optimization on the hybrid encapsulated systems using a convenient Lennard–Jones (LJ) expression of the van der Waals (vdW) intermolecular potential. Combining the density functional theory (DFT), molecular mechanics, bond polarizability model, and the spectral moment method (SMM), we computed the polarized nonresonant Raman spectra of 6T molecule and SWNTs (metallic and semiconducting) before and after encapsulation. The influence of the encapsulation on the Raman‐active modes of the 6T molecule and those of the nanotube (radial breathing modes and tangential modes) are analyzed. In particular, significant changes observed in the G‐band wavenumber. The possibility (or not) of an eventual CT between the 6T oligomer and the nanotube in both hybrid systems (6T@SWNTs and 6T‐6T@SWNTs) is discussed. We show that there is a dependence of the CT with respect to the diameter of SWNTs, the CT vanish with increasing diameter of the nanotubes. Our finding of CT behavior in the filled SWNTs with respect to SWNT diameter will provide a useful guidance for enhancing the performance of OSCs by SWNTs.

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