Carbon dating of fossils
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.
Gas proportional counting is a conventional radiometric dating technique that counts the beta particles emitted by a given sample. In this method, the carbon sample is first converted to carbon dioxide gas before measurement in gas proportional counters takes place.
Physical and chemical pretreatments are done on these materials to remove possible contaminants before they are analyzed for their radiocarbon content.American physical chemist Willard Libby led a team of scientists in the post World War II era to develop a method that measures radiocarbon activity.