Isotopes used in radiocarbon dating
When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon 14.
Experts can compare the ratio of carbon 12 to carbon 14 in dead material to the ratio when the organism was alive to estimate the date of its death.
However, pre-1950 samples that are less than 100 years old or older than 60,000 years cannot be accurately dated.
Learn how Professor Tom Higham, director of the Oxford Radiocarbon Accelerator Unit at Oxford University, has developed techniques for refining samples for AMS dating of palaeolthic bones and other artefacts.
The University of Waikato's radiocarbon dating laboratory helped to identify the remains of a woman found in New South Wales 45 years after she went missing.
A special detector called a spectrometer can ‘see’ these specks and, with the aid of a computer program, can count them and determine the date of the sample.
Accelerated mass spectrometry (AMS) is the other technique used.
Search for isotopes used in radiocarbon dating:
Liquid scintillation spectrometry involves converting all of the carbon in the sample to a liquid called benzene.