User`s guide

AC Modes 6
Agilent 5500 SPM User’s Guide 107
storage box should indicate the range in which the primary resonance
frequency will be found.
11 In the upper Auto Tune area of the AC Mode Tune window, enter
the Start and End frequencies (in kHz) for the tuning sweep. For a
new or unknown cantilever, use the stated minimum and maximum
frequencies given on the storage box. If you happen to know the
resonance frequency more exactly, you can use a smaller range to
speed the tuning process.
12 Set the Peak Amplitude, the maximum desired amplitude of
cantilever oscillation. 2 volts is a typical starting value.
13 To ensure good engagement of the tip with the sample, set the
oscillation Frequency slightly below the actual resonance frequency
of the cantilever. Enter an Off Peak value to offset the oscillation
frequency from the cantilever’s resonance frequency. A typical
starting value is -0.200 kHz.
14 Click the Auto Tune button. The system will sweep several times
through the range of frequencies, locating the peak oscillation
amplitude within the range (Figure 73). The AC signal oscillation
will be set to this value, taking into account the specified Offset.
15 Focus the cantilever in the video window.
16 Turn the video system focus knob toward you such that the tip goes
just out of focus (the focal plane is just below the tip now).
17 Press the Close switch to raise the sample until both the tip and
sample are in focus (i.e., they are nearly touching).