Krypton-81m

Krypton-81m (symbol: 81mKr) is a radioisotope of krypton that is used in various applications in the fields of medicine and environmental science. It is a metastable isotope, which means it has a higher energy state and longer half-life than the ground state isotope, Krypton-81.

Production

Krypton-81m is produced in nuclear reactors through the neutron irradiation of bromine. The bromine absorbs a neutron to become bromine-82, which then undergoes beta decay to become krypton-82. This isotope then decays to krypton-81m through isomeric transition.

Properties

Krypton-81m has a half-life of about 13 seconds. It decays to krypton-81 through isomeric transition, releasing gamma radiation with an energy of 190 keV. This radiation can be detected and used for various applications.

Applications

In medicine, krypton-81m is used in lung ventilation studies. It is inhaled by the patient and the distribution of the gas in the lungs is studied using a gamma camera. This can help to diagnose conditions such as pulmonary embolism and chronic obstructive pulmonary disease (COPD).

In environmental science, krypton-81m is used to date groundwater. The isotope is produced in the atmosphere and then absorbed into the groundwater. By measuring the amount of krypton-81m in a sample of groundwater, scientists can estimate how long the water has been in the ground.

Safety

As a radioactive isotope, krypton-81m poses a risk of radiation exposure. However, the short half-life of the isotope means that it quickly decays and the risk of exposure is therefore limited. In medical applications, the benefits of using krypton-81m generally outweigh the risks.

See also

• Isotope
• Radioisotope
• Krypton
• Metastable state
• Nuclear medicine