Cobalt57

Cobalt-57 (57Co) is a radioactive isotope of cobalt with atomic number 27 and mass number 57. It decays by electron capture to iron-57 (57Fe) with a half-life of 271.8 days. The decay process produces gamma rays, including a low-energy 14.4 keV transition from the daughter nucleus and higher-energy lines at 122 keV and 136 keV. The 14.4 keV gamma is the key feature exploited in Mössbauer spectroscopy.

Nuclear properties of 57Co include its primary decay mode (electron capture) and the resulting gamma cascade that leads to the emission of characteristic photons used for spectroscopic techniques. The isotope is valued for producing a stable, well-defined gamma source that can investigate iron-containing compounds and materials at the atomic level.

Production and availability typically involve irradiation of suitable targets in nuclear reactors or accelerators, followed by chemical separation to recover the 57Co. In practice, 57Co is supplied as sealed sources encased in robust capsules for laboratory use, ensuring containment of radioactivity while enabling controlled exposure for measurements.

Applications center on its role as a gamma-ray source for Mössbauer spectroscopy, particularly for studying iron-bearing materials, including oxidation states, bonding environments, and magnetic properties. It also serves as a calibration source for gamma detectors and as an educational demonstration of radioactive decay and spectroscopy.

Safety considerations include its radiological hazards and regulatory requirements. As a long-lived gamma emitter, 57Co sources require appropriate shielding, handling procedures, licensing, and proper storage, transport, and disposal in accordance with radiological safety standards.