|17 April 2010
New method could revolutionize dating of ancient treasures
Scientists described development of a new method to determine the age of ancient mummies, old artwork, and other relics without causing damage to these treasures of global cultural heritage. Reporting at the 239th National Meeting of the American Chemical Society (ACS), they said it could allow scientific analysis of hundreds of artifacts that until now were off limits because museums and private collectors did not want the objects damaged.
"This technique stands to revolutionize radiocarbon dating," said Marvin Rowe, Ph.D., who led the research team. "It expands the possibility for analyzing extensive museum collections that have previously been off limits because of their rarity or intrinsic value and the destructive nature of the current method of radiocarbon dating." Traditional carbon dating involves removing and burning small samples of the object. Although it sometimes requires taking minute samples of an object, even that damage may be unacceptable for some artifacts. The new method does not involve removing a sample of the object.
Conventional carbon dating estimates the age of an artifact based on its content of carbon-14 (C-14), a naturally occurring, radioactive form of carbon. Comparing the C-14 levels in the object to levels of C-14 expected in the atmosphere for a particular historic period allows scientists to estimate the age of an artifact. In Rowe's new method, called 'non-destructive carbon dating,' scientists place an entire artifact in a special chamber with a plasma, an electrically charged gas similar to gases used in big-screen plasma television displays. The gas slowly and gently oxidizes the surface of the object to produce carbon dioxide for C-14 analysis without damaging the surface, he said.
Rowe and his colleagues used the technique to analyze the ages of about 20 different organic substances, including wood, charcoal, leather, rabbit hair, a bone with mummified flesh attached, and a 1,350-year-old Egyptian weaving. The results match those of conventional carbon dating techniques, they say. The scientists are currently refining the technique. Rowe hopes to use it, for instance, to analyze objects such as a small ivory figurine called the 'Venus of Brassempouy,' thought to be about 25,000 years old and one of the earliest known depictions of a human face. The figurine is small enough to fit into the chamber used for analysis.
Source: EurekAlert! (23 March 2010)
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