
Electric Techniques
Electric Force Microscopy
Rev. D Dimension 3100 Manual 293
16.2.5 Frequency Modulation
For more quantitative results, use frequency modulation (FM). This technique provides a direct
measure of change in resonant frequency sensed by the cantilever.
1. Follow all the steps required to perform phase detection EFM.
2. In the Interleave Controls panel, set the Input feedback to Frequency.
3. Switch the Data Type for Channel 2 to Frequency.
Note: It may be necessary to optimize the FM gains in the Other Controls panel to
properly track the shifts in resonant frequency (starting values: FM igain = 40
and FM pgain = 60).
Note: For NanoScope software versions 4.23 and lower, there is no Input feedback
setting; just switch the Data Type for Channel 2 to Frequency.
16.2.6 Amplitude Detection
Amplitude detection is inferior to the phase and frequency detection methods described previously
and is not the recommended technique for systems with an Extender Electronics Module.
Amplitude detection is the only technique available for systems without the Extender Electronics
Module. This section describes the differences in set up for amplitude detection. Changes in the
cantilever amplitude provide an indirect measure of shifts in the cantilever resonance frequency as
shown in Figure 16.2q.
Figure 16.2q Shift In Amplitude at Fixed Drive Frequency
1. Set the Drive frequency to the left side of the cantilever resonance curve, as shown in Figure
16.2r.
Drive Frequency
Amplitude
∆F
0
∆
amplitude
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