Atomic Force Microscopy

Fun facts

High vacuum is not necessary. Piezoelectric position control system. The cantilever: V-shaped or single beam. V-shaped: high deflection sensitivity, not sensitive to torque. Single beam: vice-versa. Material used: diamond, tungsten, silicon. Artifacts: drift, non-linear hysterisis of piezoelectric.

Modes of operation

It is the displacement of the probe tip at the end of the cantilever that is measured. ==Contact mode== In the contact region of the potential energy curve, repulsive forces dominate. Two ways: Set height constant and measure repulsive force or set force constant and measure height. ==Tapping mode== In the semi-contact region of the potential energy curve. ==Non-contact mode== In the non-contact region of the potential energy curve, attractive forces dominate and are measured. What is observed is a an increase in the amplitude of the oscillations of the vibrating probe, translated into a change in attractive forces.