Scanning Tunneling and Atomic Force Microscope

Atomic Force Microscope (AFM) was invented by Binnig and introduced in 1985 by Binnig, Quate and Gerber as an offshoot from the Scanning Tunneling Microscope (STM).

While the STM is an ingenious instrument, which has shattered many paradigms about how to access the world of single atoms, the actual device is quite simple and grants an instructive appreciation of the concepts of atomic-scale imaging.
The AFM is somewhat more complicated and the additional challenges faced by AFM show up clearly in a direct comparison. STM and AFM have stimulated a revolution in surface science.

These techniques can image the surface of many materials with atomic resolution and provide information about the structure and organization of atomic and molecular adsorbates on surfaces.
The tip and its associated force or field can also be used to manipulate atoms and molecules to form unique structures.

However, the STM and AFM imaging mechanisms of molecular systems are not well understood. Because STM images correspond to a convolution of the tip and surface electron density-of-states near the Fermi level, molecules with deeper lying states are not expected to be readily imaged even though several examples have been reported.

STM can also be used in a spectroscopic mode to probe the electronic structure of molecular adsorbates and their interaction with the substrate.
In spite of the limitations, both STM and AFM have helped in the increase of knowledge in the domain of nanotechnology.