Chemistry

Scanning Tunneling Microscopy Studying a three Dimensional Surface



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When one thinks of the Nobel Prize generally, the mind goes to the great discoveries such as the double helix of DNA, x-rays, the decoding of the human genome and others dramatic discoveries. In many ways though, the most important discoveries are not in those final stages of understanding but the creation of the tools which allow those discoveries. One of those tools is the scanning tunneling microscope which won the 1986 noble prize for creating a tool that could allow people to see atomic scale images of metal surfaces in three dimensions.

The scanning tunneling microscope is an electron microscope that rather than optical lenses uses a conducting probe to examine the surface of the object. It does this by holding an exceedingly sharp stylus which should narrow to a single atom which scans across the surface of the metal. Since the cloud of electrons extends out a tiny distance from the surface and the needle is so narrow the two can have a strong interaction and when a current is applied you get an electron tunneling current.¹ If it works correctly it can be compared to the needle on a record player moving up and down with the surface of the object being probed and creates a contour map which is effectively a three dimensional image of the surface of the object and at a far higher ‘resolution’ than the more traditional types of microscopes².

While these three dimensional images have allowed the scanning of many different objects, including DNA molecules there are a number of limiting factors in the microscope. There is of course the difficulty of creating the tools but this has largely been overcome. Beyond that though it works best on conducting materials such as metal because of the flow of current between the two, and finally it allows the viewer to see only the surface of the object. These are all minor problems though and the technology has continued to advance overcoming most of these problems.

The scanning tunneling microscope was a huge boon to molecular science and engineering. It has allowed for advances in semiconductor physics, microelectronics and made the understanding of catalysis reactions easier as well.

As technology moves forward size becomes one of the boundaries that must be pushed against. Understanding the most basic building blocks of the universe is how we are going to build atomic level computers, nanobots which heal people from the inside, smart materials and technologies no one has even thought of yet and it all starts with technologies such as the scanning tunneling microscope which allows three dimensional images of surfaces so small that even the wavelength of light has become an issue.


1- http://physics.nist.gov/GenInt/STM/text.html

2- http://www.biologydaily.com/biology/Scanning_tunneling_microscope

3- http://nobelprize.org/educational/physics/microscopes/scanning/index.html

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