The cantilever in an AFM can be vibrated using a piezoelectric ceramic. When the vibrating cantilever comes close to a surface, the amplitude and phase of the vibrating cantilever may change. Changes in the vibration amplitude or phase are easily measured and the changes can be related to the force on the surface. This technique has many names including non-contact mode, and intermittent contact mode. It is important that the tip not "tap" the surface because the probe may be broken or the sample may be damaged.
Figure 8: In vibrating methods, changes in probes vibrations are monitored to
establish the force of the probe onto the surface. The feedback unit is used
to keep the vibrating amplitude or phase constant.
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