Géza I. Márk, László P. Biró and Joseph Gyulai
February 26, 1998
Laboratory for Nanostructure Research
Research Institute for Technical Physics and Materials Science,
H-1525
Budapest,
P.O.Box 49,
Hungary
Tel.: +36-1-392-2681
Fax: +36-1-392-2226
E-mail: mark@sunserv.kfki.hu
Electronic Properties of Novel Materials -- Progress in Molecular Nanostructures
28 February - 3. March 1998, Kirchberg, Austria,
Vol. 442,
AIP Conference Proceedings, Vol. 442. edited by Kuzmany, Hans; Fink, Jörg; Mehring, Michael; Roth, Siegmar
(American Institute of Physics,Woodbury, New York,1998) , p. 164.
Till now STM and AFM are the only tools able to probe in the
same time the physical properties and able to give information
on the geometric parameters (diameter, length) of an individual nanotube.
However, tunneling through a nanotube is a much more complex
phenomenon than STM imaging of an atomically flat crystalline surface.
Besides geometric convolution effects[1], and the resonant
tunneling through the two tunneling gaps: STM tip-nanotube, and
nanotube-substrate[2], differences in the electronic properties
of the nanotube and of the support may play a major role.
We used a method based on the wave-packet dynamical calculation
of time dependent tunneling current density in the STM
tip-nanotube-support system in order to separate the distortion
arising in the STM image formation process in pure geometric and
electronic effects.
The simulated line cuts for the case of a nanotube on a support
with similar electronic structure, and for the case of a
nanotube on a support with different electonic structure
are coincident with experimental data.
Out results show that the interpretation of scanning tunneling
spectroscopy data of carbon nanotubes has to be done with lots
of precautions.
1. L. P. Biró et al., Phys. Rev. B56(1997)12490.
2. L. P. Biró et al., Carbon, in press.