Cobalt-57

⁵⁹Co is the only stable cobalt isotope and the only isotope that exists naturally on Earth. Twenty-two radioisotopes have been characterized: the most stable, ⁶⁰Co, has a half-life of 5.2714 years; ⁵⁷Co has a half-life of 271.8 days; ⁵⁶Co has a half-life of 77.27 days; and ⁵⁸Co has a half-life of 70.86 days. All the other radioactive isotopes of cobalt have half-lives shorter than 18 hours, and in most cases shorter than 1 second.

Cobalt-57 is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by ⁵⁷Co forms an excited state of the ⁵⁷Fe nucleus, which in turn decays to the ground state with emission of a gamma ray. Measurement of the gamma ray spectrum provides information about the chemical state of the iron atom in the sample.

Cobalt-57 is also used in medical tests; it is used as a radiolabel for vitamin B12 uptake.

Spectrum (Fullscreen)

5 minute measurement with a High Purity Germanium (HPGe) radiation detector.

Metadata

Isotope:	Cobalt
Mass number:	57
Atomic number:	27
Neutron number:	30
…	…

Sources and Further Read

• https://en.wikipedia.org/wiki/Cobalt
• https://en.wikipedia.org/wiki/Isotopes_of_cobalt