The scanning tunneling microscope was invented 5 years before the atomic force microscope. However, the applications for STM are for the most part limited to studies of atomic structure in an ultra high vacuum chamber.

FIGURE 4-42 An AFM may be adapted to make STM measurements. In an STM the current between the probe and sample is used to control the distance between the probe and sample.

With pulsed force mode surface topography, adhesion and stiffness are measured simultaneously. PFM is implemented by placing a sinusoidal voltage on the Z piezo and monitoring the light lever output at key points.

FIGURE 4-43 In pulsed force mode the probe is moved in the Z axis in a sinusoidal motion.

An AFM probe may be used to move nanoscale objects on a surface. The motion may be performed in an open loop format with special software, or in a closed loop format with a haptic interface.