[Click for Main Data] Proton Emission Neutron Emission Electron Emission Positron Emission
Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
Americium has no naturally occurring isotopes.
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 230 | ≈ 17 seconds | Electron Capture | 100.00% |
| 231 | No Data Available | Alpha Decay (suspected) | No Data Available |
| Electron Capture (suspected) | No Data Available | ||
| 232 | 79 seconds | Electron Capture | ~ 97.00% |
| Alpha Decay | ~ 3.00% | ||
| 233 | 3.2 minutes | Alpha Decay | > 3.00% |
| Electron Capture | No Data Available | ||
| 234 | 2.32 minutes | Electron Capture | 100.00% |
| Alpha Decay | No Data Available | ||
| 235 | 10.3 minutes | Alpha Decay | 0.40% |
| Electron Capture | 99.60% | ||
| 236 | 3.6 minutes | Alpha Decay | No Data Available |
| Electron Capture | No Data Available | ||
| 236m | 2.9 minutes | Alpha Decay | No Data Available |
| Electron Capture | No Data Available | ||
| 237 | 73.6 minutes | Electron Capture | 99.97% |
| Alpha Decay | 0.03% | ||
| 238 | 98 minutes | Electron Capture | 100.00% |
| Alpha Decay | 1.0×10-4 % | ||
| 239 | 11.9 hours | Alpha Decay | 0.01% |
| Electron Capture | 99.99% | ||
| 240 | 50.8 hours | Electron Capture | 100.00% |
| Alpha Decay | 1.9×10-4 % | ||
| 240m | 0.94 milliseconds | Spontaneous Fission | <= 100.00% |
| 241 | 432.6 years | Alpha Decay | 100.00% |
| Spontaneous Fission | 4×10-10 % | ||
| 242 | 16.02 hours | Beta-minus Decay | 82.70% |
| Electron Capture | 17.30% | ||
| 242m | 141 years | Isomeric Transition | 99.55% |
| Alpha Decay | 0.45% | ||
| Spontaneous Fission | < 4.7×10-9 % | ||
| 242m1 | 14.0 milliseconds | Spontaneous Fission | 100.00% |
| Isomeric Transition | No Data Available | ||
| Alpha Decay | < 5.0×10-3 % | ||
| 243 | 7370 years | Alpha Decay | 100.00% |
| Spontaneous Fission | 3.7×10-9 % | ||
| 244 | 10.1 hours | Beta-minus Decay | 100.00% |
| 244m | 0.90 milliseconds | Spontaneous Fission | <= 100.00% |
| 244m1 | 26 minutes | Beta-minus Decay | 99.96% |
| Electron Capture | 0.04% | ||
| 245 | 2.05 hours | Beta-minus Decay | 100.00% |
| 246 | 39 minutes | Beta-minus Decay | 100.00% |
| 246m | 25.0 minutes | Beta-minus Decay | 100.00% |
| Isomeric Transition | < 0.02% | ||
| 247 | 23.0 minutes | Beta-minus Decay | 100.00% |
| 248 | ≈ 10 minutes | Beta-minus Decay | 100.00% |
| 249 | No Data Available | Beta-minus Decay (suspected) | No Data Available |
This page is maintained by Steve Gagnon.