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Q Control Applications
Ultrathin
Organic Films
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sample:
Langmuir-Blodgett film (ethyl-2,3-dihydroxyoctadecanoate)
on mica
scan range: 8.6 µm x 8.6 µm
data: topography / data range: 25 nm |
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Topographical image of Langmuir-Blodgett
Film
The image clearly shows that the highly sensitive sample
surface can only be imaged non-destructively with active
Q-Control. The periodic repulsive contact with the probe
in standard tapping operation without Q-Control leads
to a significant modification or destruction of the
surface structure.
Data courtesy of Nanoanalytics
and Dr.Lifeng Chi and coworkers, Physikalisches Institut,
Westfälische Wilhelms-Universität Münster
DNA
Ring Structures
Sample: DNA ring structure [chimera
biotec GmbH]
Scan range: 1 µm x 1 µm
Data type: topography / data range: 8 nm
This example shows that non-destructive
imaging of DNA ring structures is possible in standard
mode, however, Q-Control enables a clear improvement
in resolution.
Data courtesy Dr. Lifeng
Chi and coworkers, Physikalisches Institut, Westfälische
Wilhelms-Universität Münster.
Magnetic
Recording Media
Sample: hard disk with digital
magnetic data structures
Scan range: 5 µm x 5 µm
Left data type: topography / data range: 20 nm
Right data type: phase shift / data range: 10 deg
The left image shows the surface
topography of a computer hard disk measured in standard
tapping mode. The upper part of the right image shows
the magnetic data structures as they were recorded simultaneously
in standard mode, whereas in the lower part of the image
Q-Control was activated. It is clearly visible that
the application of Q-Control leads to a significant
improvement of the overall sensitivity and thereby to
an amplification of the magnetic contrast. Note that
except for that Q-factor, all parameters, e.g. oscillation
amplitude, lift height and scan speed, were kept constant
during the entire scan.
Further investigations revealed
that the signal-to-noise ratio of such measurements
on magnetic fields can be improved significantly:
This analysis of measurements
on a magnetic tape shows that the signal amplitude (upper
diagrams), i.e. the image contrast, was increased by
a factor of 12.4 by Q-Control. However, in order to
assess the improvement in overall sensitivity it is
more relevant to analyze the signal-to-noise ratio.
Just by looking at the cross-sections it is already
obvious that Q-Control leads to an significant improvement,
i.e. less noise. The detailed statistical analysis of
averaged data (lower diagrams) revealed an increase
of the signal-to-noise ratio by a factor of 2.3 .
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