Scanning tunneling microscopy electrical properties

The first and best known near-field technique to measure electrical properties in the nanoscale is of course Scanning Tunnelling Microscopy (STM). Since its invention by Binnig et al., STM has been used to explore the mechanisms of lots of phenomena on surfaces [289-294], ranging from experiments concerning the local work function to the use of an STM-tip to induce electropolymerisation [295]. Most of all, STM provides us with atomically resolved images of the surface structure. 

Quantum mechanics describes and defines the behavior of electrons in atoms. One of the rules of quantum behavior is that electrons are constrained to specific locales known as orbitals within the structure of an atom and are not allowed to exist at the boundaries of those locales. An observable property called quantum mechanical tunneling occurs, however, which permits electrons to move from one locale to another across the orbital boundaries. In scanning probe microscopy the miniscule electrical current due to quantum mechanical tunneling between the atoms at a surface and the atoms at the tip of an atomic-scale probe is measured as a function of their relative positions. This provides a corresponding atomic scale map of the surface structure. 

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