Veeco Dimension 3100, Руководство пользователя

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Fluid Imaging
Operating Principles
166 Dimension 3100 Manual Rev. D
damped. Instead, this step is used to find an oscillating frequency specific to the fluid and cantilever
holder where the cantilever can be driven into oscillation.
Enter the View > Sweep > Cantilever Tune menu to select a drive frequency. The optimal drive
frequency can depend upon sample, fluid and fluid volume inside the fluid cell. Experiment to find
the best drive frequency for specific imaging conditions. Two frequency ranges that are commonly
used are 16-19kHz and 8-12kHz; higher frequencies have also been used. Start with a
Sweep width
of 20kHz. Users of TappingMode in air will notice that their is not a single well-defined resonance,
but instead a large number of broad peaks. The peaks are resonances of the fluid cell and fluid, and
do not usually depend so much on the cantilever dimensions.
A typical Cantilever Tune screen is shown in Figure 10.5c . It is necessary to select a frequency
where there is some cantilever response, (i.e., near a peak), but experience suggests that it is best to
avoid the tops and sides of extremely sharp peaks. The best frequencies appear to be on the side of
a peak or in a shallow valley between peaks.
Figure 10.5c shows a typical operating frequency that
produces good fluid tapping images.
Figure 10.5c Typical Cantilever Tune Curve for Silicon Nitride Tip in Fluid
1. In the Feedback Controls panel, set Z Modulation to Enabled .
2. Select View > Sweep > Cantilever Tune , or click on the Cantilever Tune icon. The
initial Cantilever Tune panel appears with the Frequency Sweep (a plot of cantilever
response as a function of applied oscillation frequency) on the display monitor.
3. In the Cantilever Tune panel, set the Drive frequency parameter to 10kHz and the Sweep
width parameter to 20kHz .
4. Set the Drive amplitude to 200mV .
5. Zero the Amplitude setpoint .
6. Set the Amplitude limit to 2.5V .
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