Isotopes of cobalt

Naturally occurring cobalt, Co, consists of a single stable isotope, ⁵⁹Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are ⁶⁰Co with a half-life of 5.2714 years, ⁵⁷Co (271.811 days), ⁵⁶Co (77.236 days), and ⁵⁸Co (70.844 days). All other isotopes have half-lives of less than 18 hours and most of these have half-lives of less than 1 second. This element also has 19 meta states, of which the most stable is ^58m1Co with a half-life of 8.853 h.

The isotopes of cobalt range in atomic weight from ⁵⁰Co to ⁷⁸Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, ⁵⁹Co, is electron capture and the main mode of decay for those of greater than 59 atomic mass units is beta decay. The main decay products before ⁵⁹Co are iron isotopes and the main products after are nickel isotopes.

Radioisotopes can be produced by various nuclear reactions. For example, ⁵⁷Co is produced by cyclotron irradiation of iron. The main reaction is the (d,n) reaction ⁵⁶Fe + ²H → n + ⁵⁷Co.^[4]