carbon 13

Also found in: Encyclopedia.

car·bon 13 (13C),

A stable natural isotope, 1.1% of natural carbon.
References in periodicals archive ?
They found that the carbon 13 percentage in the background organic matter in the surrounding rock was different from that of the microstructures.
Artificial norandrosterone contains lower levels of carbon 13 than carbon 12, because it is produced from a plant source with less carbon 13 than normal dietary sources.
Carbon 12 has six protons and six neutrons in its nucleus while the carbon 13 nucleus has one more neutron.
As a consequence, carbonates precipitated from seawater that is rich in algae and bacteria will have proportionately more carbon 13 than the carbon dioxide expelled from volcanoes.
Recently, scientists at General Electric's Research and Development Center in Schenectady, New York, synthesized large, gem-quality diamonds composed almost entirely of the isotope carbon 13.
The analyzer uses laser-based mid-infrared spectroscopy to simultaneously measure carbon 13 isotope and oxygen 18 isotope with a precision of better than 0.
For example, carbon 13 is a heavier (and rare) version of the most common type of carbon, called carbon 12.
The urea in Pranactin, however, is composed of a form of carbon called carbon 13, which is not commonly found in breath.
Both sets of cores also show similar changes in carbon 13 through time, indicating that the changes in carbon isotopes occurred worldwide and oxygen levels throughout the atmosphere were high.
When microbes degrade contaminants, they prefer the lighter isotope carbon 12 over the heavier isotope carbon 13.