Operating instructions

DYNAMIC FORCE
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Both the Force Modulation mode and the Spreading Resistance mode are
an extension of the Static Force mode.
The procedure for a first Static Force mode measurement is basically the
procedure described for the Dynamic Force mode in chapter ‘A first meas-
urement’. The main differences are:
- Use a suitable cantilever type (usually CONTR), and select this type in
the Operating Mode panel.
- Select the Static Force mode in the Operating Mode panel.
- Set the force Set point in the Z-Controller panel.
Dynamic Force
In the Dynamic Force mode, changes in the dynamic behaviour of the can-
tilever are detected by measuring changes in its vibration amplitude when
it is excited with a sinusoidal signal with a frequency close to the cantilever’s
free resonance frequency. When the cantilever tip comes close to the sample
surface, this vibration amplitude will generally go down. Thus the set point
is the percentage of the vibration amplitude when the cantilever was far
away from the surface. A small percentage means a big reduction, a large
percentage means a small reduction. To minimize tip/sample wear, the set
point should be made as large as possible. However, when the Set-point
becomes too large, the Z-Controller may not be able to optimally follow the
sample surface, and artifacts may occur due to instabilities in the cantilever
vibration.
The procedure for a first Dynamic Force mode measurement is described
for the Dynamic Force mode in chapter ‘A first measurement’. For more
information on how the vibration amplitude and frequency are set, refer to
the Software Reference manual.
Phase Contrast
The Phase Contrast mode is an extension of the Dynamic Force mode. In
addition to the vibration amplitude, the phase shift between the cantilever