azote14

Azote14, more commonly known as nitrogen-14, is the most abundant isotope of the element nitrogen. It has seven protons and seven neutrons, giving a mass number of 14. It is stable and non-radioactive, and it constitutes the vast majority of nitrogen found in Earth's atmosphere. The nucleus has a spin of 1 and a quadrupole moment, which influences how 14N behaves in magnetic resonance experiments and can complicate high-resolution NMR spectra.

Natural abundance and chemistry

In the atmosphere, about 99.6% of the nitrogen is 14N, with the remainder mainly 15N. Chemically, 14N behaves the same as other nitrogen isotopes because isotope effects are small for most reactions, so nitrogen-containing compounds incorporate 14N and 15N at nearly identical rates. Because 14N is a quadrupolar nucleus (I > 1/2), its nuclear magnetic resonance signals are often broadened, making 14N NMR less straightforward to interpret compared with 15N NMR, which uses spin-1/2 nuclei.

Occurrence and formation

14N is produced in stars through the CNO cycle, a catalytic sequence that fuses hydrogen into helium and leaves nitrogen as a byproduct. In the interstellar medium and cosmic-ray interactions, 14N is a stable, long-lived constituent of nitrogen-containing materials. On Earth, atmospheric N2 is dominated by 14N, and it serves as a reservoir for biological nitrogen through fixation and assimilation.

Applications

Nitrogen-14 is used in isotopic studies where the natural abundance ratio of 14N to 15N is important, such as isotope ratio mass spectrometry to investigate metabolic and environmental processes. In addition, 14N plays a role in certain nuclear and astrophysical models, including simulations of the CNO cycle in stars. For detailed molecular tracing, 15N is often preferred due to its favorable NMR properties.