Instruction manual

Force Imaging
Force Modulation
Rev. B MultiMode SPM Instruction Manual 209
n. Adjust the Drive amplitude so the maximum response amplitude is about 1V. Recenter
the peak if necessary.
Figure 11.6e Correctly Tuned Force Modulation Frequency
Note: You may also change the Drive Frequency by clicking on the Drive
Frequency parameter on the control monitor’s Feedback Controls panel, and
entering a new value.
Note: Bimorph resonance should be between 5 kHz and 30 kHz. If peaks are found at
a much higher frequency, these are cantilever resonances, not bimorph
resonances.
o. Record the Drive frequency. This is the resonant frequency of your force modulation
bimorph.
9. Bring the tip near the sample with the manual motor controls.
10. Check the scan parameters Scan speed, Scan size and Integral gain to verify they are
reasonable for Contact Mode AFM imaging. Also, it may be desirable to readjust the detector
mirror adjustment screws if the Vertical Difference signal has drifted from the value
originally set.
11. For the Channel 1 image, select Data Type > Height. Select Data Type > Amplitude for
the Channel 2 image. The multi-image capability views both the topography data and the
force modulation (elasticity) data at the same time.
12. Reduce the Drive Amplitude to 0 before engaging.
13. Select Motor > Engage.
Note: The motor moves the SPM head down towards the sample and stops once the
cantilever deflects to the chosen Setpoint. Under some conditions the system
may “false engage” before the cantilever actually reaches the surface. Increase
the Setpoint and engage again.
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