54Fe

54Fe is a stable isotope of the element iron with mass number 54. It contains 26 protons and 28 neutrons in its nucleus. As one of the four stable iron isotopes, 54Fe coexists with 56Fe, 57Fe, and 58Fe. The ground-state nuclear spin of 54Fe is 0+, and it does not undergo radioactive decay.

Natural occurrence and properties are characterized by its isotopic abundance and atomic mass. In nature, iron is a mixture of its stable isotopes, with 54Fe contributing a modest fraction (approximately 5–6%) of total iron. The atomic mass of 54Fe is about 53.9396 atomic mass units. Like other even-even nuclei, 54Fe is predicted to be highly stable, and no radioactive decay products are observed under ordinary conditions.

Origin in the cosmos and production mechanisms are tied to stellar nucleosynthesis. Iron isotopes are produced predominantly in the late stages of massive star evolution and during supernovae, where silicon burning, neutron capture, and explosive nucleosynthesis set the relative abundances of iron-peak isotopes. The precise balance of 54Fe versus other iron isotopes in stars and meteorites provides information about stellar histories and nucleosynthetic processes.

Applications and relevance include isotopic studies in geochemistry and cosmochemistry. The 54Fe/56Fe ratio is used as a tracer in planetary differentiation and meteorite investigations. Unlike 57Fe, which is commonly used in Mössbauer spectroscopy, 54Fe is not Mössbauer-active. In isotope ratio mass spectrometry, 54Fe serves as part of the natural iron isotope spectrum for calibration and interpretation.