14N

14N is the most common isotope of nitrogen, having a mass number of 14 and an atomic number of 7. Its nucleus contains seven protons and seven neutrons, and it is stable, not undergoing radioactive decay.

In nature, about 99.63% of atmospheric nitrogen is 14N, with the remaining ~0.37% being the stable isotope 15N. Together these two isotopes account for essentially all nitrogen found on Earth. In stellar nucleosynthesis, 14N is produced and processed in the CNO cycle and can act as a bottleneck that influences the rate of energy production in some stars.

Nuclear properties of 14N include a nuclear spin of I = 1, which makes it a quadrupolar nucleus. This leads to rapid quadrupolar relaxation and broad signals in nitrogen-14 magnetic resonance spectroscopy, making 14N NMR less convenient than that of spin-1/2 nuclei. Consequently, 15N NMR is more commonly used in labeling and tracing experiments.

Applications of 14N arise mainly from its abundance and stability. It is widely used as a stable isotope tracer in chemistry and biology, particularly in isotopic labeling studies and mass spectrometry analyses. Because it is non-radioactive, it poses no radiological hazard and serves as a reference or internal standard in various measurements.

See also: nitrogen isotopes, isotopic labeling, mass spectrometry, nuclear magnetic resonance.