The latter slow down, again by colliding with matter in the atmosphere.
A 1 gram sample of carbon from living material shows an activity of about 14 disintegrations per minute. If an excavated sample of plant or animal origin from an archaeological site had a measured activity of 7 disintegrations per minute (dpm), the age of the sample could be fixed at about 5,730 years ± 40 years.
It involves converting the carbon in only a very small piece of the artefact to carbon dioxide gas by controlled combustion.
The carbon present in the gas is then converted to a small plug of a graphite/iron composite.
Liquid scintillation spectrometry involves converting all of the carbon in the sample to a liquid called benzene.
A special chemical is added to the sample that produces tiny specks of light called scintillations when carbon-14 atoms decay.