SCANNING TUNNELLING MICROSCOPY (STM)
IMAGING OF CARBON NANOTUBES
L. P. Biró*, ,
J. Gyulai*, Ph. Lambin**, J. B.Nagy**, S. Lazarescu**,
G.I. Márk*, A. Fonseca**, P. R. Surján***, Zs. Szekeres***,
P. A. Thiry**, and A. A. Lucas**
*KFKI-Research Institute for Materials Science, H-1525 Budapest, P. O. Box.
49, Hungary
**Institute for Studies in Interface Sciences, Facultés
Universitaires Notre-Dame de la Paix, rue de Bruxelles 61, B-5000 Namur,
Belgium
***Department of Theoretical Chemistry, Eötvös University, H-1518,
POB 32, Hungary
Corresponding author:
L. P. Biró
Tel.: +36-1-3959220
Fax: +36-1-3959284
E-mail: biro@mfa.kfki.hu
Invited talk at E-MRS Spring Meeting,
June 16-20, 1997, Strasbourg, France.
Symposium A: Fullerenes and Carbon Based Materials
Carbon 36, 689(1998)
http://www.mfa.kfki.hu/int/nano/reprint/Carbon_36_689.pdf
To look at the animtions of electron tunneling
through a carbon nanotube
click here!
Abstract
Carbon nanotubes prepared by thermal decomposition of hydrocarbons on
supported Co catalysts were investigated by STM in air. An interpretation of
the STM images is proposed which accounts for specific distortions taking place
while scanning three-dimensional objects whose dimensions are of the order of
the curvature radius of the tip. These distortions have both geometric and
electronic origins, and cannot be neglected. The distortion mechanism was found
to be different for nanotube diameters in the ranges of 1 nm and 10 nm. The
1-nm tubes are more strongly affected by their apparent broadening reflecting
the finite size of the tip apex. Here the distortion can reach up to 300% of
the geometric diameter, whereas for 10-nm tubes the distortions are in the
range of 50% of the geometric diameter. An apparent flattening of the nanotubes
in the vertical direction was also found, which is attributed to differences in
electronic densities of states between the substrate and the nanotube, and to
an additional tunnelling barrier between the nanotube and the substrate. STM
images with atomic resolution and line-cut topographic profiles show similar
structures as for the case of HOPG. However, the atomic corrugation was found
five times smaller on the 1-nm diameter tubules than for the 10-nm family, the
latter being close to the value obtained with HOPG. Coiled nanotubes have been
imaged by STM for the first time. Here both the electrical resistance of the
coiled nanotube and its elastic deformation play a significant role in the
image formation process, these effects being more important than for straight
nanotubes.
Last updated: Sep 26, 2002
Geza I. Mark
mark@sunserv.kfki.hu
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