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Comparison of simulated and experimental line
cuts shows that when the nanotube is placed on a support with
similar electronic structure (on the top of
the raft, (Fig. 1.), the
geometric line cut does not differ significantly from the
quantum line cut (Cf. Fig. 7.).
Major distortion that influences the apparent tube diameter is
geometric convolution of the tip with the tube.
When the nanotube is on a support with different electronic
properties, the simplification used in the quantum line
cut calculation:
EF and W in the nanotube and in the support
is identical, is not valid. In case of the geometric
line cut this can be taken in account
by increasing the value of the tunneling gap over the support
as compared to the value over the nanotube.
This resuls in
a continuous increase of distortion in the apparent
diameter of the nanotube with increase of difference in
electronic structure of the nanotube as compared to graphite.
Ratio of HW to h versus increase of
tunneling gap over the support is shown in
Fig. 8..
Figure 8:
HW / h versus increase of tunneling gap above
the support.
Definition of HW, h, and gap increase is given on
the geometric line cut shown on the inset.
Comparing the case of the nanotube over the raft, i.e. identical electronic
structure, with Fig. 8.,
one may conclude that in the experimental case the distortion agrees
within experimental error with the value corresponding to zero
tunnel gap increase in the figure.
Next: Conclusion
Up: Simulation of STM images
Previous: Quantum line cut