
TappingMode AFM
Withdrawing the Tip
Rev. B MultiMode SPM Instruction Manual 115
7.4 Withdrawing the Tip
Select Withdraw from the Motor menu. The SPM will stop scanning, then ascend
approximately 10µm. If more clearance between tip and sample is desired, toggle the Up / Down
switch on the top-right side of the MultiMode base. Never withdraw samples without carefully
observing that the tip has adequate clearance during the entire sample removal sequence.
7.5 Beyond Basics with Resonating Techniques
This section discusses some of the subtle aspects of the operation of the MultiMode in
TappingMode. Without a thorough understanding of principles associated with cantilever
resonating techniques, distorted data may be generated. Understanding the Cantilever Tune
process and the effects of Realtime scan parameters is very important to effective operation of the
microscope. It is also very important to understand similarities and differences between the force
calibration mode of contact AFM and force calibration mode while in TappingMode.
7.5.1 Subtleties of Cantilever Oscillation
The response of the cantilever to inputs plays an important role in the operation of the MultiMode
microscope while in TappingMode. There is an important trade-off between the response time of
the cantilever and the force applied to the sample. The cantilever does not respond instantly to
perturbations in its vibrational amplitude. The cantilever drive system pumps energy gradually into
the cantilever oscillation. Figure 7.5a shows a typical response curve of the cantilever amplitude as
a function of time. To demonstrate the conflicting requirements, the performance of the system will
be analyzed at two operating points.
Figure 7.5a Cantilever Response Curve
∆x
∆x
Free Amplitude
∆t
2
∆t
1
Time
Cantilever Vibration Amplitude
Setpoint 1
Setpoint 2
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