Describe carbon dating
Most samples require chemical pre-treatment to ensure their purity or to recover particular components of the material.The objective of pre-treatment is to ensure that the carbon being analyzed is native to the sample submitted for dating.Working with several collaboraters, Libby established the natural occurrence of radiocarbon by detecting its radioactivity in methane from the Baltimore sewer.In contrast, methane made from petroleum products had no measurable radioactivity.AMS technology has allowed us to date very small samples (such as seeds) that were previously undatable.Since there are practical limits to the age range of the method, most samples must be younger than 50,000 years and older than 100 years.
Targets tuned to different atomic weights count the number of c12, c13, and c 14 atoms in a sample.Any organic material that is available in sufficient quantity can be prepared for radiocarbon dating.Modern AMS (accelerator mass spectroscopy) methods require tiny amounts, about 50 mg. Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials. Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.