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Carbon-12 (12 C) is the most abundant of the two stable isotopes of carbon (carbon-13 being the other), amounting to 98.93% of element carbon on Earth; [1] its abundance is due to the triple-alpha process by which it is created in stars.
Carbon (6 C) has 14 known isotopes, from 8 C to 20 C as well as 22 C, of which 12 C and 13 C are stable.The longest-lived radioisotope is 14 C, with a half-life of 5.70(3) × 10 3 years. . This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reactio
C / 12 C ratio is used instead of 14 C / 12 C because the former is much easier to measure, and the latter can be easily derived: the depletion of 13 C relative to 12 C is proportional to the difference in the atomic masses of the two isotopes, so the depletion for 14 C is twice the depletion of 13 C. [22] The fractionation of 13
The isotope carbon-12 (12 C) forms 98.93% of the carbon on Earth, while carbon-13 (13 C) forms the remaining 1.07%. [69] The concentration of 12 C is further increased in biological materials because biochemical reactions discriminate against 13 C. [ 70 ] In 1961, the International Union of Pure and Applied Chemistry (IUPAC) adopted the isotope ...
Carbon is a necessary component of all known life. 12 C, a stable isotope of carbon, is abundantly produced in stars due to three factors: The decay lifetime of a 8 Be nucleus is four orders of magnitude larger than the time for two 4 He nuclei (alpha particles) to scatter. [19]
Carbon-14 is a radioactive isotope of carbon, with a half-life of 5,730 years [30] [31] (which is very short compared with the above isotopes), and decays into nitrogen. [32] In other radiometric dating methods, the heavy parent isotopes were produced by nucleosynthesis in supernovas, meaning that any parent isotope with a short half-life ...
Carbon on Earth naturally occurs in two stable isotopes, with 98.9% in the form of 12 C and 1.1% in 13 C. [1] [8] The ratio between these isotopes varies in biological organisms due to metabolic processes that selectively use one carbon isotope over the other, or "fractionate" carbon through kinetic or thermodynamic effects. [1]
Nitrogen-15, or 15 N, is often used in agricultural and medical research, for example in the Meselson–Stahl experiment to establish the nature of DNA replication. [12] An extension of this research resulted in development of DNA-based stable-isotope probing, which allows examination of links between metabolic function and taxonomic identity of microorganisms in the environment, without the ...