There are three principal techniques used to measure carbon 14 content of any given sample— gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry. Liquid scintillation counting is another radiocarbon dating technique that was popular in the 1960s.There are three principal techniques used to measure carbon 14 content of any given sample— gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry

Why is carbon-14 used for radiocarbon dating?

Carbon-14 is considered a radioactive isotope of carbon. Because its unstable, carbon-14 will eventually decay back to carbon-12 isotopes. And thats the key to radiocarbon dating. Scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive.

Why are radiocarbon dates expressed as a range?

The overlapping nature of the tree records means this is the most accurate record we have. There will of course be several possible calendar years within the expected range, which is why radiocarbon dates come with a variation such as +/- 25 years for example (11).