Isotopes of carbon

Isotopes of carbon
Name	Carbon isotopes
Mass range	8–22
Stable isotopes	12, 13
Notable radioisotopes	14, 11, 10
Discovery	1912 (mass spectrometry developments)

Contents

Isotopes of carbon

Isotopes of carbon are nuclides of the chemical element carbon with atomic number 6 and varying mass numbers; they include the stable nuclides with mass numbers 12 and 13 and a suite of radioactive isotopes such as carbon-14. Studies of carbon isotopes intersect work by figures and institutions such as Willard Libby, Ernest Rutherford, J. J. Thomson, Francis Aston, Caltech, and Los Alamos National Laboratory, and inform research at organizations like the Scripps Institution of Oceanography and Smithsonian Institution.

Overview

Carbon isotopes span mass numbers from 8 to 22, produced in processes examined by researchers at Cavendish Laboratory, University of Cambridge, and Massachusetts Institute of Technology. Early mass spectrometry by Francis Aston and instrumentation advances at National Institute of Standards and Technology enabled differentiation of carbon-12 and carbon-13, underpinning standards adopted by bodies such as the International Union of Pure and Applied Chemistry and the International Atomic Energy Agency. The distribution and applications of carbon isotopes feature prominently in studies led at centers including Lawrence Berkeley National Laboratory and Max Planck Society institutes.

Two isotopes occur naturally in appreciable amounts: carbon-12 and carbon-13. Carbon-12 defines the mole and atomic mass standard set by committees at the International Committee for Weights and Measures and influenced by metrologists at Bureau International des Poids et Mesures. Carbon-13 is used in investigations by teams at University of Oxford, Harvard University, and University of California, Berkeley for paleoclimate work, metabolic tracing in research groups at Johns Hopkins University, and plant physiology studies at University of Cambridge. Natural terrestrial, marine, and atmospheric reservoirs sampled by expeditions from the National Oceanic and Atmospheric Administration, British Antarctic Survey, and Monterey Bay Aquarium Research Institute show distinct 12C/13C ratios exploited in biogeochemical research.

Radioactive isotopes include carbon-14, carbon-11, carbon-10, and short-lived nuclides such as carbon-8 and carbon-9 investigated at facilities like CERN, GSI Helmholtz Centre for Heavy Ion Research, and RIKEN. Carbon-14, discovered through work by Willard Libby and collaborators at University of Chicago, revolutionized archaeology with applications in projects at the British Museum, Metropolitan Museum of Art, and Yale Peabody Museum. Carbon-11 is produced for positron emission tomography at medical centers including Mayo Clinic, Johns Hopkins Hospital, and Massachusetts General Hospital. Exotic isotopes have been synthesized in experiments at Brookhaven National Laboratory and through collaborations involving European Organization for Nuclear Research investigators.

Production pathways involve cosmic-ray spallation in the upper atmosphere, neutron activation in reactors such as those at Oak Ridge National Laboratory, and accelerator-driven reactions at TRIUMF and Lawrence Livermore National Laboratory. Measurement techniques include accelerator mass spectrometry developed at University of Arizona, gas proportional counting historically used by teams at University of California, Berkeley, and liquid scintillation counting in laboratories at Pacific Northwest National Laboratory. Isotope ratio mass spectrometry employed by groups at University of Edinburgh, ETH Zurich, and Woods Hole Oceanographic Institution yields high-precision 13C/12C data used in collaborations with museums and archives like the Natural History Museum, London.

Carbon isotopes underpin radiocarbon dating employed in excavations conducted by archaeologists affiliated with University College London, Australian National University, and the Smithsonian Institution. Carbon-11 labeled radiotracers enable neurological and oncology studies at centers such as Scripps Research, Dana–Farber Cancer Institute, and Stanford University School of Medicine. Carbon-13 enrichments are utilized in metabolic flux analysis by biotech firms and research groups associated with Biogen, Novo Nordisk, and academic labs at ETH Zurich. Environmental monitoring programs by United States Geological Survey, European Environment Agency, and International Oceanographic Commission use carbon isotopes to trace carbon cycle dynamics, while climate reconstructions rely on isotope data curated by archives like the National Climatic Data Center.

Nuclear properties such as binding energy curves and decay schemes were elucidated by physicists at Cavendish Laboratory and theoretical work from Institute for Advanced Study collaborators. Carbon-14 decays by beta emission to nitrogen-14 and is central to chronologies used by institutions like Smithsonian Institution; carbon-11 decays by positron emission useful for PET imaging in hospitals such as Massachusetts General Hospital. Exotic isotopes display proton emission, neutron emission, or rapid multi-particle decay studied at GANIL and RIKEN Nishina Center in experiments coordinated with researchers from University of Tokyo and Technical University of Munich.

Isotopic fractionation processes affecting 12C/13C ratios are investigated in contexts studied by field teams from Lamont–Doherty Earth Observatory, Scripps Institution of Oceanography, and Plymouth University; biological fractionation in plants and microbes informs paleobotany work at Royal Botanic Gardens, Kew and microbial ecology studies at Max Planck Institute for Marine Microbiology. Marine carbonate records curated at Natural History Museum, London and ice core archives at British Antarctic Survey use carbon isotope signals to reconstruct paleoatmospheric CO2 linked to research by climate scientists at IPCC and NOAA. Fractionation models developed in collaborations including European Space Agency investigators assist planetary scientists at NASA Jet Propulsion Laboratory studying organic carbon in meteorites held by the National Museum of Natural History.

Category:Isotopes