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Published June 6, 2012 | public
Journal Article

4D Electron Microscopy Visualization of Anisotropic Atomic Motions in Carbon Nanotubes


We report the anisotropic atomic expansion dynamics of multi-walled carbon nanotubes, using 4D electron microscopy. From time-resolved diffraction on the picosecond to millisecond scale, following ultrafast heating at the rate of 10^(13) K/s, it is shown that nanotubes expand only in the radial (intertubule) direction, whereas no significant change is observed in the intratubular axial or equatorial dimensions. The non-equilibrium heating occurs on an ultrafast time scale, indicating that the anisotropy is the result of an efficient electron−lattice coupling and is maintained up to equilibration. The recovery time, which measures the heat dissipation rate for equilibration, was found to be on the order of ∼100 μs. This recovery is reproduced theoretically by considering the composite specimen−substrate heat exchange.

Additional Information

© 2012 American Chemical Society. Received: April 26, 2012; Publication Date (Web): May 16, 2012. This work was supported by the National Science Foundation and the Air Force Office of Scientific Research in the Physical Biology Center for Ultrafast Science and Technology (UST) supported by the Gordon and Betty Moore Foundation at Caltech. The authors thank Dr. Anthony W. Fitzpatrick for carefully reading the manuscript. The authors declare no competing financial interest.

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