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Carbon-13 (13 C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. As one of the environmental isotopes , it makes up about 1.1% of all natural carbon on Earth.
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
Foraminifera samples. In geochemistry, paleoclimatology, and paleoceanography δ 13 C (pronounced "delta thirteen c") is an isotopic signature, a measure of the ratio of the two stable isotopes of carbon— 13 C and 12 C—reported in parts per thousand (per mil, ‰). [1]
Similarly, marine fish contain more 13 C than freshwater fish, with values approximating the C 4 and C 3 plants respectively. The ratio of carbon-13 and carbon-12 isotopes in these types of plants is as follows: [11] C 4 plants: −16‰ to −10‰ CAM plants: −20‰ to −10‰ C 3 plants: −33‰ to −24‰
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]
The major isotope of carbon, the 12 C isotope, has a spin quantum number of zero and so is not magnetically active and therefore not detectable by NMR. 13 C, with a spin quantum number of 1/2, is not abundant (1.1%), whereas other popular nuclei are 100% abundant, e.g. 1 H, 19 F, 31 P.
The Suess effect is a change in the ratio of the atmospheric concentrations of heavy isotopes of carbon (13 C and 14 C) by the admixture of large amounts of fossil-fuel derived CO 2, which contains no 14 CO 2 and is depleted in 13 CO 2 relative to CO 2 in the atmosphere and carbon in the upper ocean and the terrestrial biosphere . [1]
A carbon-13 label was used to determine the mechanism in the 1,2- to 1,3-didehydrobenzene conversion of the phenyl substituted aryne precursor 1 to acenaphthylene. [3]An isotopic tracer, (also "isotopic marker" or "isotopic label"), is used in chemistry and biochemistry to help understand chemical reactions and interactions.