Force Imaging
Force Calibration Mode
Rev. B
MultiMode SPM Instruction Manual
181
Controls
panel de
fi
nes the rate at which the piezo completes an extension-retraction cycle (and
therefore the rate at which new curves are displayed).
11.2.2 Contact AFM Force Plots
Figure 11.2d
Anatomy of a Force Curve
Here, the horizontal axis plots sample movement. The sample is raised toward the probe by
extending the Z-axis piezo crystal, which is plotted from right-to-left in white on the NanoScope
display monitor. A sample descent is achieved by retracting the Z-axis piezo crystal, which is
plotted from left-to-right in yellow on the NanoScope display monitor.
2
3
4
5
1
Piezo extension
Piezo retraction
Cantile
ver deflection
6
Up
Do
wn
1
2
5
6
Piezo extends; tip descends. No contact with surface yet.
3
Tip is pulled down by attractive forces near surface.
As tip presses into the surface, cantilever bends upward.
As piezo continues retracting, tip finally breaks free of
surface attraction. Cantilever rebounds sharply upward.
4
Piezo retracts. Cantilever relaxes downward until tip forces
7
are in equilibrium with surface forces.
7
As piezo continues retracting, tip continues its ascent.
No further contact with surface during this cycle.
Piezo continues retraction. Cantilever bends downward as
surface attraction holds onto the tip.
