Definition of carbon 14 dating
There is a useful diagrammatic representation of this process given here Libby, Anderson and Arnold (1949) were the first to measure the rate of this decay.They found that after 5568 years, half the C14 in the original sample will have decayed and after another 5568 years, half of that remaining material will have decayed, and so on (see figure 1 below)."Everything which has come down to us from heathendom is wrapped in a thick fog; it belongs to a space of time we cannot measure.We know that it is older than Christendom, but whether by a couple of years or a couple of centuries, or even by more than a millenium, we can do no more than guess." [Rasmus Nyerup, (Danish antiquarian), 1802 (in Trigger, 19)].Libby and his team intially tested the radiocarbon method on samples from prehistoric Egypt.They chose samples whose age could be independently determined.Renfrew (1973) called it 'the radiocarbon revolution' in describing its impact upon the human sciences.Oakley (1979) suggested its development meant an almost complete re-writing of the evolution and cultural emergence of the human species.
Writing of the European Upper Palaeolithic, Movius (1960) concluded that "time alone is the lens that can throw it into focus".As 14C decays it emits a weak beta particle (b ), or electron, which possesses an average energy of 160ke V.The decay can be shown: Thus, the 14C decays back to 14N.The radiocarbon method was developed by a team of scientists led by the late Professor Willard F.Libby of the University of Chicago in immediate post-WW2 years.
The 14C formed is rapidly oxidised to 14CO2 and enters the earth's plant and animal lifeways through photosynthesis and the food chain.