Scanning tunneling microscope

Atomic resolution Au100

Scanning Tunneling Microscope

The Scanning Tunneling Microscope (STM) is a powerful instrument used for imaging surfaces at the atomic level. Its development in 1981 by Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory, for which they were awarded the Nobel Prize in Physics in 1986, marked a significant advancement in the field of nanotechnology. STM is based on the concept of quantum tunneling, and it allows scientists to visualize and manipulate individual atoms and molecules on a surface.

Principles of Operation

The STM operates on the principle of quantum tunneling. When a conducting tip is brought very close to the surface to be imaged, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The tunneling current is a function of the tip's position, the applied voltage, and the local density of states of the sample. By scanning the tip across the surface and measuring the tunneling current, a topographic map of the surface at atomic resolution can be generated.

Components

The key components of an STM include a sharp conducting tip, a piezoelectric scanner that moves the tip in all three spatial dimensions, and a control unit that maintains the tip's position with respect to the surface. The resolution of an STM is such that it can differentiate between individual atoms.

Applications

STMs have a wide range of applications in both fundamental and applied sciences. They are used in physics, chemistry, material science, and biology for surface analysis. This includes imaging the arrangement of atoms and molecules, studying surface irregularities, and manipulating atoms to create nanostructures.

Advantages and Limitations

One of the main advantages of STM is its ability to image and manipulate individual atoms and molecules. However, its operation requires extremely stable and clean conditions, and it can only be used on conductive or semiconductive surfaces.

See Also

• Atomic Force Microscope
• Nanotechnology
• Quantum Tunneling
• Surface Science

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