Experimentally, a carbon containing sample is burnt in a stream of oxygen to produce carbon dioxide. The methane is produced by reaction of carbon dioxide with hydrogen over a ruthenium catalyst. After purification the methane is passed into a heavily shielded gas proportional counter over an extended period of 1,000 minutes. The count rate gives the information on the amount of carbon 14, while , in theory, a knowledge of the volume of the counter and the gas pressure can be used to estimate the amount of total carbon. The count rate from the unknown sample relative to these other two determinations can be used to determine the age.
Radiocarbon dating is of importance in many fields.
The more important of these are in archaeology, anthropology, history and in geography. The later may not seem as obvious as the first three, however a study of shell deposits can provide information about the movement of shorelines and tree fragments buried in sand or silt deposits can provide information related to the change in course of a river and sometimes indicate past periods of flood. Carbon dating has also been used to verify claims relating to the authenticity of antiques or documents. The second field mentioned at the beginning was that of geochronology - the dating of rocks. Although these studies have been going on for decades, it has only been in more recent years that their significance has reached the popular press in relation to space exploration and the dating of lunar samples.