From combined Raman spectroscopy and electron diffraction studies on several freestanding single-walled carbon nanotubes (SWNTs), we define Raman criteria which correlate the main features of the Raman spectrum (radial breathing mode and G modes) and the optical transition energies with the structure of the SWNT under investigation. On this basis, we discuss the possibilities to determine the (n,m) indices of an individual SWNT from a single wavelength Raman experiment. We show the efficiency of this approach in assigning the (n,m) structure of different individual nanotubes including all types of achiral SWNTs. Finally, the limits and the accuracy of the method are discussed

We study single wall carbon nanotubes (SWNTs) deposited on quartz. Their Raman spectrum depends on the tube-substrate morphology, and in some cases, it shows that the same SWNT-on-quartz system exhibits a mixture of semiconductor and metal behavior, depending on the orientation between the tube and the substrate. We also address the problem using electric force microscopy and ab initio calculations, both showing that the electronic properties along a single SWNT are being modulated via tube-substrate interaction.

We report in situ Raman scattering experiments on single-layer graphene (SLG) and Bernal bilayer graphene (BLG) during exposure to rubidium vapor. The G- and 2D-band evolutions with doping time are presented and analyzed. On SLG, the extended doping range scanned (up to about 10(14) electrons/cm(2)) allows the observation of three regimes in the evolution of the G-band frequency: a continuous upshift followed by a plateau and a downshift. Overall the measured evolution is interpreted as the signature of the competition between dynamic and adiabatic effects upon n-doping. Comparison of the obtained results with theoretical predictions indicates however that a substrate pinning effect occurs and inhibits charge-induced lattice expansion of SLG. At low doping, a direct link between electrostatic gating and Rb doping results is presented. For BLG, the added electrons are shown to be first confined in the top layer, but the system evolves with time toward a more symmetric repartition of the added electrons in both layers. The results obtained on BLG also confirm that the slope of the phonon dispersion close to the K point tends to be slightly reduced at low doping but suggest the occurrence of an unexpected increase of the phonon dispersion slope at higher electron concentration.

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We review the main information that we have obtained from combined Raman spectroscopy and electron diffraction experiments on individual free-standing single-walled carbon nanotubes. This information concerns: the radial breathing mode vs. diameter relationship; the dependence of the frequency and lineshape of the G-modes in semiconducting and metallic tubes; the evaluation of the optical transition energies for individual free-standing SWNTs. From these data, we can define Raman criteria allowing the indexing of carbon nanotubes from their Raman features only. We show the efficiency of this approach to assign the (n,m) indices of individual chiral and achiral single-walled carbon nanotubes. These criteria are also applied to identify tubes grown on a substrate from a single wavelength Raman experiments. These results obtained on index-identified individual nanotubes are compared with theoretical predictions.

We review the information that we have obtained from combined Raman spectroscopy and electron diffraction experiments on individual free-standing single-walled carbon nanotubes (SWNT). From these data, we define Raman criteria allowing the indexing of SWNTs from their Raman features only and we show the efficiency of this approach in assigning the structure of individual carbon nanotubes. These results on index-identified individual SWNTs are compared with theoretical predictions.

Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon-carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C-C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.

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