Krypton-85
| General | |
|---|---|
| Symbol | 85Kr |
| Names | krypton-85 |
| Protons (Z) | 36 |
| Neutrons (N) | 49 |
| Nuclide data | |
| Half-life (t1/2) | 10.728 years |
| Isotope mass | 84.9125273(21) Da |
| Spin | 9/2+ |
| Excess energy | −81480.267 keV |
| Binding energy | 8698.562 keV |
| Decay products | 85Rb |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| Beta decay | 0.687 |
| Beta decay | 0.173 |
| Isotopes of krypton Complete table of nuclides | |
Krypton-85 (85Kr) is a radioisotope of krypton, distributed throughout the atmosphere and presently forming about 15 ppt of atmospheric krypton on average.
Krypton-85 has a half-life of 10.728 years and a maximum decay energy of 687 keV.[1] It decays into stable rubidium-85. Its most common decay (99.57%) is by beta particle emission with a maximum energy of 687 keV and an average energy of 251 keV. The second most common decay (0.43%) is by beta particle emission (maximum energy of 173 keV) followed by gamma ray emission (energy of 514 keV). Other decay modes have very small probabilities and emit less energetic gamma rays.[2] Krypton-85 is mostly synthetic, though it is produced naturally in trace quantities by cosmic ray spallation.
In terms of radiotoxicity, 440 Bq of 85Kr is equivalent to 1 Bq of radon-222, without considering the rest of the radon decay chain.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.