carbon 12

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car·bon 12 (12C),

The standard of atomic mass, 98.90% of natural carbon.
References in periodicals archive ?
SAM's mass spectrometer and tunable laser spectrometer independently measured virtually identical ratios of carbon-13 to carbon-12.
In the journal article, Rutgers said the researchers detail a way to facilitate the of anaerobic bacteria in cleaning up MTBE by employing carbon isotope fractionation -- the changes in the isotopic ratios of carbon (its different molecular versions, carbon-12 and carbon-13) brought about from the selective degradation of the carbon-12 form in the case of MTBE.
Living things tend to have a preference for the carbon-12 isotope in their make-up.
The resulting levels of carbon-12, carbon-13, and carbon-14 in atmospheric methane reflect these source and sink contributions.
By measuring the ratio of carbon-13 to carbon-12 in the methane gas, researchers will be able to distinguish whether it came from Martian rocks or from methane-producing microorganisms that may have existed on the planet.
Carbon-12, an essential element we're all made of, can only form when three alpha particles, or helium-4 nuclei, combine in a very specific way.
That could be because tree leaves prefer to take in gas made of carbon-12, leaving the heavier version in the air.
This process favors loss of a lighter isotope named carbon-12 compared to carbon-13.
Chemical analyses indicate that the mini-gems contain higher-than-average concentrations of the carbon-12 isotope, researchers report in the July 3 Nature.
The stable isotopes, carbon-12 and carbon-13, are derived from Earth's mantle, and released when carbon-bearing rocks weather at the surface.
About 99 percent of carbon in non-living stuff is carbon-12, a lighter version of the element than the carbon-13 that accounts for most of the remaining 1 percent.
An atomic weight of I corresponds to an average mass equal to one-twelfth the mass of the carbon-12 nucleus.