![]() However, open-air nuclear testing between 19 contributed to this pool. The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. A gram of carbon containing 1 atom of carbon-14 per 10 12 atoms will emit ~0.2 beta particles per second. Carbon-14 has a maximum specific activity of 62.4 mCi/mmol (2.31 GBq/mmol), or 164.9 GBq/g. Carbon-12 and carbon-13 are both stable, while carbon-14 is unstable and has a half-life of 5700 ☓0 years. There are three naturally occurring isotopes of carbon on Earth: carbon-12 ( 12Ĭ), which makes up 99% of all carbon on Earth carbon-13 ( 13Ĭ), which makes up 1% and carbon-14 ( 14Ĭ), which occurs in trace amounts, making up about 1 or 1.5 atoms per 10 12 atoms of carbon in the atmosphere. Its existence had been suggested by Franz Kurie in 1934. Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples. Carbon-14, 14Cġ part per trillion = 1 / 10 12 Ĭ or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. For the dating technique, see Radiocarbon dating. ![]() For the scientific journal, see Radiocarbon (journal). ![]()
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