
TappingMode AFM
Advanced TappingMode AFM Operation
Rev. D Dimension 3100 Manual 145
Figure 9.4c Scope Trace with Correct Scan Rate
9.4.3 Decreasing the Cantilever Drive Frequency
The Drive frequency selected to oscillate the cantilever plays an important role in the performance
of the microscope while in TappingMode. As a first step it is important to determine the resonant
frequency of the cantilever, but the Drive frequency could be further tuned to improve scanning
performance.
The microscope produces better data in TappingMode when the Drive frequency is set lower than
the resonant peak of the cantilever. The Drive frequency is set such that it coincides with a 1-10
percent decrease in the oscillation amplitude by setting Peak offset in the Auto Tune controls to the
desired percent. Figure 9.4d shows a suggested operating region. This is a suggestion based on our
observations; users are encouraged to experiment with the microscope and decide what produces
the best results.
Figure 9.4d Suggested Range of Drive Frequencies
Z Range
50.00 nm/div
Scan Size - 2.50 µm/div
Trace
Retrace
Cantilever
Response
12.54 nm/div
Center Frequency - 338.8723 KHz
5.0 KHz/div
Setpoint
Drive Frequency
should
be within this range.
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