How confinement affects the dynamics of c60 in carbon nanopeapods.

Institut Laue Langevin, F-38042 Grenoble, France.
Physical Review Letters (Impact Factor: 7.73). 09/2008; 101(6):065507. DOI: 10.1103/PhysRevLett.101.065507
Source: PubMed

ABSTRACT The dynamics of confined systems is of major concern for both fundamental physics and applications. In this Letter, the dynamics of C60 fullerene molecules inside single walled carbon nanotubes is studied using inelastic neutron scattering. We identify the C60 vibrations and highlight their sensitivity to temperature. Moreover, a clear signature of rotational diffusion of the C60 is evidenced, which persists at lower temperature than in 3D bulk C60. It is discussed in terms of confinement and of reduced dimensionality of the C60 chain.

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    ABSTRACT: Fullerenes inserted in single-walled carbon nanotubes, the so-called “peapods,” provide scientists with an exceptional molecular model system to study one-dimensional physics and confinement. In this communication, we present recent inelastic neutron scattering measurements concerning the translational dynamics of this one-dimensional system. The recent synthesis of a large amount of two-dimensional oriented samples allows us to extract the sole contribution of the inserted C60 chains. The related quasi-elastic-like peak evolves with the temperature but never shows an additional inelastic contribution when lowering temperature, indicating that carbon peapod is a true one-dimensional system down to low temperatures.
    Fullerenes Nanotubes and Carbon Nanostructures - FULLER NANOTUB CARBON NANOSTR. 01/2012; 20:395-400.
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    ABSTRACT: This work is dedicated to the study of the structural and dynamical behavior of a model one-dimensional system over a wide temperature range : carbon nano-peapods. This compound is constituted of fullerenes (C60, in our case) inserted inside single-walled carbon nanotubes. The perfect match between the inner diameter of the tubes and the diameter of the fullerenes results in a chain organization of the C60 molecules. The synthesis of these peapods is described in the first part of this manuscript. The two next chapters are aimed to the description of the different experimental and simulation methods that are used to monitor the structural and dynamical behavior of the C60 molecules. In the three last chapters, we describe the behavior of the C60 molecules over three tempe- rature ranges, labeled high (500–1100 K), low (0–200 K), and intermediary (200–500 K) ranges. By comparing experimental results to analytical models for both monomer and polymer pea- pods (the rotational degree of freedom being hindered in the latter), we highlight three different behaviors of the molecules in these three ranges.
    11/2012, Degree: PhD, Supervisor: Stéphane Rols and Pascale Launois
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    ABSTRACT: We report an inelastic neutron-scattering investigation of the longitudinal acoustic modes of C60 chains confined inside single walled carbon nanotubes. We take advantage of the orientations of the chains within the plane of the pellet sample to isolate their scattering signatures in the (Q,ω) space, which we follow as a function of temperature from 260 K up to 1100 K. The results show the progressive evolution of the confined chain from a one-dimensional (1D) crystal to a linear liquid, the transition occurring within a temperature range of ∼150 K centered around 600 K. The comparison of the data obtained on monomer and polymer peapods allows extracting the speed of sound in the monomer crystalline chains (vmono=3.5 km s−1, vpoly/vmono=1.7). We find that the sound velocity is further reduced by half in the liquid state which reveals that the melting is not only due to harmonic additive thermal fluctuations, but that anharmonic terms in the intermolecular potential play an important role at high temperatures.
    Physical Review B 05/2013; 87:195438. · 3.66 Impact Factor

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