Force Imaging
Force Calibration (TappingMode)
230
Dimension 3100 Manual
Rev. D
the sample surface, the oscillation amplitude of the cantilever decreases as the piezo is extended.
When the piezo turns around and begins to retract, the oscillation amplitude of the cantilever
increases until the tip is free of the surface, leveling off at the free-air amplitude (point 5).
Channel 2
(bottom) in
plots average cantilever deflection (TM deflection) versus
piezo extension. The deflection signal is low-pass filtered to eliminate the high-frequency
TappingMode oscillation. Even as tip RMS amplitude dampens during its encounters with the
sample surface, the average deflection is unchanged. This condition changes once the tip is so close
to the sample that all oscillation ceases. Extending the piezo still further causes the average
deflection to increase, applying an increasing force to the sample (point 2).
,the cantilever begins to deflect. The region between points 3 and 4 may
be hazardous to the tip, because the tip is pressed firmly against the sample surface. Most single
crystal silicon TappingMode tips rapidly become dull in this region, depending upon the hardness
of the sample.
13.5.2 Obtaining a Force Plot (TappingMode)
When obtaining force plots in TappingMode, set up scan parameters so that the reduction of
amplitude is minimal (approximately 25 percent of the free air amplitude). If the amplitude is
reduced to zero, the tip and sample may sustain damage.
To generate a TappingMode force plot of a silicon calibration reference, complete the following
steps:
1. Verify the cantilever holder is loaded with a TappingMode tip.
2. Mount the calibration reference on the SPM stage.
3. Set the
AFM mode
parameter to
Tapping
, engage, and obtain a TappingMode image.
Note:
You are now in
Image mode
.
4. To switch to
Force Mode
, click on the
Realtime
>
View
>
Force Mode
>
Calibration
or
Advanced
option. At least two panels should be visible:
•
Main Controls
•
Channel 1 Panel
CAUTION:
Use
Force Calibration
with caution or when it is important to
obtain experimental information shown in
Force Calibration.
When using stiff TappingMode cantilevers, it is easy to blunt the
tip with excess contact force during
Force Calibration
measurements.
Содержание Dimension 3100
Страница 12: ...xii Dimension 3100 Manual Rev D ...
Страница 20: ...List of Figures xx Dimension 3100 Manual Rev D ...
Страница 72: ......
Страница 106: ......
Страница 118: ......
Страница 214: ...Scanning Tunneling Microscopy STM Etching Tungsten Tips 194 Dimension 3100 Manual Rev D ...
Страница 222: ......
Страница 266: ......
Страница 274: ......