Laure Noé

Coefficient of thermal expansion of carbon nanotubes measured by Raman spectroscopy

The coefficient of thermal expansion (CTE) of peapod-derived double-walled carbon nanotubes and their host empty single-walled carbon nanotubes (SWCNTs) was determined using Raman spectroscopy. This was performed by measuring the dependence of Raman band frequency of the nanotubes in epoxy resin matrix composites and considering the effects of both the strain and temperature on the Raman bands. Both types of nanotubes show positive thermal expansion at room temperature of around +2 × 10−5 K−1, and the CTE of the SWCNTs was unaffected by the introduction of the inner wall nanotubes. It was also demonstrated that the temperature-induced Raman band shifts can be used to determine both the CTE and glass transition temperature of the matrix polymers.

Nanoelectromechanical coupling in fullerene peapods probed by resonant electrical transport experiments

Fullerene peapods, which are carbon nanotubes encapsulating fullerene molecules, can offer enhanced functionality with respect to empty nanotubes. Their prospective applications include, for example, data storage devices, single-electron transistors and spin-qubit arrays for quantum computing. However, the present incomplete understanding of how a nanotube is affected by entrapped fullerenes is an obstacle for peapods to reach their full potential in nanoscale electronic applications. In this paper, we investigate the effect of C(60) fullerenes on low-temperature electron transport through peapod quantum dots. Compared with empty nanotubes, we find an abnormal temperature dependence of Coulomb blockade oscillations, indicating the presence of a nanoelectromechanical coupling between electronic states of the nanotube and mechanical vibrations of fullerenes. This provides a method to detect the C(60) presence and to probe the interplay between electrical and mechanical excitations in peapods, which thus emerge as a new class of nanoelectromechanical systems.

Sub-Kelvin transport spectroscopy of fullerene peapod quantum dots

The authors have studied electrical transport properties of individual C60 fullerene peapods, i.e., single-wall carbon nanotubes encapsulating C60 molecules. Their measurements indicated power lawlike temperature dependencies of linear conductance similar to those for empty nanotubes. At temperatures below 30K, peapod devices behaved as highly regular individual quantum dots showing regular Coulomb blockade oscillations. Signatures of Kondo physics appeared at the lowest measurement temperature of 315mK.

Discriminated structural behaviour of C60 and C70 peapods under extreme conditions

We studied structural changes in C 60 and C 70 peapods — i.e. C 60 and C 70 chains inserted inside single-walled carbon nanotubes— when submitted to high pressure and temperature conditions. X-ray diffraction experiments showed that while C 60 molecules polymerize inside nanotubes at pressures and temperatures consistent with polymerization in bulk C 60 phases, no polymerization is observed in C 70 peapods, even at pressures and temperatures above the threshold for polymerization in bulk C 70 . Tubular confinement in the nanotube container prevents the monomers to rearrange in the way needed for polymerization. This result testifies for the strong influence of confinement on the behaviour of C 70 .

Discriminated structural behaviour of C60and C70peapods under extreme conditions

We studied structural changes in C 60 and C 70 peapods — i.e. C 60 and C 70 chains inserted inside single-walled carbon nanotubes— when submitted to high pressure and temperature conditions. X-ray diffraction experiments showed that while C 60 molecules polymerize inside nanotubes at pressures and temperatures consistent with polymerization in bulk C 60 phases, no polymerization is observed in C 70 peapods, even at pressures and temperatures above the threshold for polymerization in bulk C 70 . Tubular confinement in the nanotube container prevents the monomers to rearrange in the way needed for polymerization. This result testifies for the strong influence of confinement on the behaviour of C 70 .

Discriminated structural behaviour of

We studied structural changes in C 60 and C 70 peapods — i.e. C 60 and C 70 chains inserted inside single-walled carbon nanotubes— when submitted to high pressure and temperature conditions. X-ray diffraction experiments showed that while C 60 molecules polymerize inside nanotubes at pressures and temperatures consistent with polymerization in bulk C 60 phases, no polymerization is observed in C 70 peapods, even at pressures and temperatures above the threshold for polymerization in bulk C 70 . Tubular confinement in the nanotube container prevents the monomers to rearrange in the way needed for polymerization. This result testifies for the strong influence of confinement on the behaviour of C 70 .