Scanning tunneling microscope

Scanning tunneling microscopy (RTM) structure and function are similar to the scanning force microscope (AFM).

An electrically conductive needle and/or head scans the sample surface. The quantum-mechanical tunneling is the correlation process (an atomic particle is able to surpass a potential barrier of limited height also if its energy is lower than the barrier height (Wikipedia)). In presence of applied potential between the head and the sample surface this results in a measurable tunnel current.