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What fingerprinting is to the F.B.I., spectroscopy is to the scientist. Through its use, astronomers have been able to learn more about the chemical composition of the sun than is known about the composition of the earth. Spectroscopy is used in food research to find impurities in canned food and cans of beer; it is used to trace the origin of paint found on a car in a hit-and-run accident; or to determine how jewelry was made centuries ago. Just how does this technique work? It is a simple story as explained by physicists at Argonne National Laboratory. Yet its applications are extremely precise. The basic instrument is the spectroscope, which can be as simple as a piece of glass used to split sunlight into a “rainbow” of color or as complicated as a piece of delicate apparatus that can single out sixty thousand different colors and requires a room as big as a small house. The use of spectroscopy was extremely important during the development of the atomic bomb. Large quantities of uranium and graphite were needed to produce the bomb, and scientists knew that the very success of the project depended on obtaining these elements in their purist forms. Using a spectroscope, scientists were able to measure the purity of the valuable elements. They knew that each element emits certain colors in the same manner that each man has different fingerprints. Thus, scientists could “look” at two pictures of different samples of uranium and determine which was the purer, since uranium containing impurities gave a different color or wavelength when photographed and compared with photographs of light from pure uranium. Scientists have spent literally years studying photographic plates from the spectrograph to determine the frequencies of light from specimens of chemical elements. The measurement and interpretation is an exacting and time-consuming task which is important if scientists are to understand the structure of atoms.
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