Abstract Submitted to the    CCTN09 Symposium:

Structural studies of carbon nanohorns by neutron and X-ray diffraction

Andrzej Burian ¹, Lukasz Hawelek ², Wojciech Wrzalik ², Aleksander Brodka ², Andrzej Burian ², John Charles Dore ³, Alex Hannon ⁴, Katsumi Kaneko ⁵

¹ A. Chelkowski Institute of Physics, University of Silesia
² A. Chelkowski Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland
³ School of Physical Sciences, University of Kent, Canterbury, CT2 7NR, UK
⁴ Rutherford Appleton Laboratoty, Chilton, Didcot, Oxfordshire OX11 0QX, UK
⁵ Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-Shi, Chiba 263-8522, Japan

andrzej.burian@us.edu.pl

XIII. Atomic Structure of Carbon Nanotubes

The structure of carbon nanohorns produced by laser ablation at room temperature without a metal catalyst [1] has been studied using the neutron and X-ray diffraction techniques and the molecular dynamics (MD) method. The neutron diffraction measurements were carried out on the GEM (GEneral Materials diffractometer) at the Rutherford Appleton Laboratory. The scattering data were measured up to the scattering vector Qmax=30 Å^-1 (Q=4πsinθ/λ, where 2θ is the scattering angle and λ is the wavelength). The X-ray diffraction data were recorded using a laboratory diffractometer with the monochromatized Ag radiation up to Qmax=22 Å^-1. The collected diffraction data have been converted to a real space representation in the form of the pair correlation function via the Fourier transform. The structural model consisting of a nanocone with the cone angle approximately 20o and a single-wall carbon nanotube of about 35 nm in length and 2 nm, 2.5 nm and 3 nm in diameter has been computer generated starting from a single graphite layer. The presence of the defects in the form of pentagon-heptagon pairs via the Stone-Wales mechanism has been considered [2]. Then this model has been relaxed using the MD method with the reactive empirical bond order potential [3] for carbon-carbon interaction and the Lennard-Jones potential with parameters for inter-layer interactions [4]. Correctness of a such constructed model has been verified by comparison of the simulations and the experimental data in both real and reciprocal space.

[1] S. Iijima, M. Yudasaka, R. Yamada, S. Bandow, K. Suenaga, F. Kokai, K. Takahashi, Chem. Phys. Lett. 309 (1999) 165.
[2] A.J. Stone, D.J. Wales, Chem. Phys. Lett. 128 (1986) 501.
[3] D.W. Brenner, O.A. Shenderova, J.A. Harrison, S.J. Stuart, B. Ni, S.B. Sinott, J. Phys. Condens. Matter 4 (2002) 783.
[4] L.A. Girifalco, M. Hodak, R.S. Lee, Phys. Rev. B62 (2000) 13104.

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