Isotopes of carbon
Carbon isotopes and mainly C-13 is used extensively in many different applications. C-13 is used for instance in organic chemistry research, studies into molecular structures, metabolism, food labeling, air pollution and climate change. C-13 is also used in breath tests to determine the presence of the helicobacter pylori bacteria which causes stomach ulcer. C-13 can also be used for the production of the radioisotope N-13 which is a PET isotope. The C-12 atom has been given the atomic weight of exactly 12.000000000 and is used as the basis upon which the atomic weight of other isotopes is determined. Carbon isotopes in the form of BaCO3 can be obtained from Trace Sciences International.
Naturally occurring isotopes
This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of carbon are listed (including any which occur naturally) below.
||Atomic mass (ma/u)
||Natural abundance (atom %)
||Nuclear spin (I)
||Magnetic moment (μ/μN)
|| 12.000 000 0(0)*
|| 13.003 354 8378(10)
In the above picture, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which total 100% for all the naturally occurring isotopes.
Further data for naturally occuring isotopes of carbon are listed above. This table gives information about some radiosotopes of carbon, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
||Mode of decay
||Nuclear magnetic moment
||EC to 9B; EC + p to 8Be; EC + 2α to 2H
||EC to 10B
||EC to 11B
||β- to 14N
||β- to 15N
||β- to 16N
||β- to 17N; β- + n to 16N
- Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
- For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides
- Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]
NMR Properties of carbon
Common reference compound: Si(CH3)4/CDCl3 (1%).
- R.K. Harris in Encyclopedia of Nuclear Magnetic Resonance, D.M. Granty and R.K. Harris, (eds.), vol. 5, John Wiley & Sons, Chichester, UK, 1996. I am grateful to Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC, adapted from his contribution contained within this reference.
- J. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. Where given, data for certain radioactive nuclei are from this reference.
- P. Pyykkö, Mol. Phys., 2008, 106, 1965-1974.
- P. Pyykkö, Mol. Phys., 2001, 99, 1617-1629.
- P. Pyykkö, Z. Naturforsch., 1992, 47a, 189. I am grateful to Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data in this and the following two references.
- D.R. Lide, (ed.), CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.
- P. Pyykkö, personal communication, 1998, 204, 2008, 2010.
- The isotopic abundances are extracted from the naturally occurring isotopes section within WebElements.