The foundation of material property mapping with
PeakForce QNM is the ability of the system to acquire
and analyze the individual force curves from each tap
that occurs during the imaging process. To separate the
contributions from different material properties such as
adhesion, modulus, dissipation, and deformation, it is
necessary to measure the instantaneous force on the
tip rather than a time-average of the force or dissipation
over time, as is done in TappingMode PhaseImaging.
This requires a force sensor that has a significantly higher
bandwidth than the frequency of the periodic interactions In Peak Force Tapping, the modulation frequency is
intentionally chosen to be significantly lower than the
cantilever resonant frequency. The force measurement
bandwidth of a cantilever is approximately equal to the
resonant frequency of the fundamental bending mode used
for force detection. As a result, a properly chosen cantilever
is able to respond to changes in instantaneous interaction
force with an immediate deflection change during Peak
Force Tapping