Atomic Force Microscopy

Nano-Observer AFM image strip

Since the introduction of the Nobel Prize-winning scanning tunneling microscope (STM) and then the invention of the atomic force microscopy (AFM) from the landmark publication by Binnig, Quate, and Gerber, the field of scanning probe microscopy has exploded well beyond using interatomic forces to image topography on the nanometer scale. The ability to measure intermolecular forces and see atoms is scientifically tantalizing.

Topography imaging alone does not always provide the answers that researchers need and the surface topology often does not correlate to the material properties. For these reasons, advanced imaging modes have been developed to provide quantitative data on a variety of surfaces. Now, many material properties can be determined with AFM techniques, including friction, electrical forces, capacitance, magnetic forces, conductivity, viscoelasticity, surface potential, and resistance.

Scanning Tunneling Microscopy

The development of the family of scanning probe microscopes started with the original invention of the STM in 1981. Gerd Binnig and Heinrich Rohrer developed the first working STM while working at IBM Zurich Research Laboratories in Switzerland. This instrument would later win Binnig and Rohrer the Nobel prize in physics in 1986.

Atomic Force Microscopy

The atomic force microscope (AFM) was developed to overcome a basic drawback with STM - it can only image conducting or semiconducting surfaces. The AFM has the advantage of imaging almost any type of surface, including polymers, ceramics, composites, glass, and biological samples.

Binnig, Quate, and Gerber invented the AFM in 1985. Their original AFM consisted of a diamond shard attached to a strip of gold foil. The diamond tip contacted the surface directly, with the interatomic van der Waals forces providing the interaction mechanism. Detection of the cantilever’s vertical movement was done with a second tip - an STM placed above the cantilever.


 

How an AFM Works
How an AFM Works

Basics of atomic force microscopy

AFM:  Contact Modes
AFM: Contact Modes

Overview of AFM contact imaging modes

AFM:  Dynamic Modes
AFM: Dynamic Modes

Overview of AFM dynamic imaging modes

AFM:  Electrical Modes
AFM: Electrical Modes

Overview of AFM electric imaging modes