Carbon 14 dating wood
To measure the amount of radiocarbon left in a artifact, scientists burn a small piece to convert it into carbon dioxide gas.
Radiation counters are used to detect the electrons given off by decaying Carbon-14 as it turns into nitrogen.
Radiocarbon dating is the principal method for determining the age of carbon-bearing materials from the present to about 50,000 years ago.
The method takes advantage of the natural occurrence of a radioactive isotope of carbon (C in samples of ancient carbon compounds and comparing this with the amount in modern materials, it is possible to determine the time of cessation of carbon exchange with the atmosphere.
Radiocarbon present in molecules of atmospheric carbon dioxide enters the biological carbon cycle: it is absorbed from the air by green plants and then passed on to animals through the food chain.
In order to date the artifact, the amount of Carbon-14 is compared to the amount of Carbon-12 (the stable form of carbon) to determine how much radiocarbon has decayed.
The ratio of carbon-12 to carbon-14 is the same in all living things.
Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food.
Once the organism dies, however, it ceases to absorb carbon-14, so that the amount of the radiocarbon in its tissues steadily decreases.