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Windows on the Atomic World
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19342 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
6 / 1991 |
2,716 Words |
| Author
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Gerald R. Campbell
Gerald R. Campbell is a research scientist and science writer
in Saint Louis, Missouri. |
Since the time of the Greek philosophers, scientists have spoken of atoms--the "indivisible units of matter" that are the building blocks of all material things. Most people have seen drawings in chemistry texts showing atoms and molecules, but no one ever seriously expected to be able to see single atoms. The thought of moving a single atom in a controlled fashion was dismissed as farfetched, mere science fiction fantasy.
Until now, that is.
With the development of the scanning tunneling microscope (STM) in 1982, a wide range of atomic surfaces became visible for the first time. Such claims were initially viewed with skepticism by a conservative scientific community. As Gerd Binning and Heinrich Rohrer, coinventors of the STM, put it in their 1986 Nobel Prize lecture, "It seemed there was still a conflict between the very appealing, conceptual easiness of displaying individual atoms in three-dimensional real space ... and the intuitive reservation that, after all, it just could not be that simple."
But overcoming its initial suspicions, the scientific community has wholeheartedly embraced this powerful imaging technology, as well as a growing cluster of allied technologies that have sprung from the original instrument. Having the coinventors of the technique awarded the 1986 Nobel Prize in physics didn't hurt, either. Right now the field is exploding, growing in the United States from a handful of workers in 1985 to well over 1,000 labs today, with representatives from 22 countries attending the latest annual Conference on Scanning Tunneling Microscopy/Spectroscopy.
In the past five years, the basic technology developed by Binning and Rohrer has been adapted so that there now exists such an array of variant technologies, called scanning probe microscopes, that it is possible to look at virtually any surface, and at different aspects of the surface, quickly, cheaply, and reproducibly. Commercial STMs are now available and cost less than a scanning electron microscope, the previous standard for surface imaging. Other benefits of the new scanning probe microscopes are that they do not require the arduous, highly technical, and time-consuming sample preparation required by the scanning electron microscope.
Nor is looking at atoms all that this technology allows. By proper manipulation of the electric fields around the tip, atoms can be attracted and repelled, and thus moved from place to place (see
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