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Isotopes of the Element Americium

[Click for Main Data]

Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information.

Naturally Occurring Isotopes

Americium has no naturally occurring isotopes.

Known Isotopes

Mass NumberHalf-lifeDecay ModeBranching Percentage
230≈ 17 secondsElectron Capture100.00%
231No Data AvailableAlpha Decay (suspected)No Data Available
Electron Capture (suspected)No Data Available
23279 secondsElectron Capture~ 97.00%
Alpha Decay~ 3.00%
2333.2 minutesAlpha Decay> 3.00%
Electron CaptureNo Data Available
2342.32 minutesElectron Capture100.00%
Alpha DecayNo Data Available
23510.3 minutesAlpha Decay0.40%
Electron Capture99.60%
2363.6 minutesAlpha DecayNo Data Available
Electron CaptureNo Data Available
236m2.9 minutesAlpha DecayNo Data Available
Electron CaptureNo Data Available
23773.6 minutesElectron Capture99.97%
Alpha Decay0.03%
23898 minutesElectron Capture100.00%
Alpha Decay1.0×10-4 %
23911.9 hoursAlpha Decay0.01%
Electron Capture99.99%
24050.8 hoursElectron Capture100.00%
Alpha Decay1.9×10-4 %
240m0.94 millisecondsSpontaneous Fission<= 100.00%
241432.6 yearsAlpha Decay100.00%
Spontaneous Fission4×10-10 %
24216.02 hoursBeta-minus Decay82.70%
Electron Capture17.30%
242m141 yearsIsomeric Transition99.55%
Alpha Decay0.45%
Spontaneous Fission< 4.7×10-9 %
242m114.0 millisecondsSpontaneous Fission100.00%
Isomeric TransitionNo Data Available
Alpha Decay< 5.0×10-3 %
2437370 yearsAlpha Decay100.00%
Spontaneous Fission3.7×10-9 %
24410.1 hoursBeta-minus Decay100.00%
244m0.90 millisecondsSpontaneous Fission<= 100.00%
244m126 minutesBeta-minus Decay99.96%
Electron Capture0.04%
2452.05 hoursBeta-minus Decay100.00%
24639 minutesBeta-minus Decay100.00%
246m25.0 minutesBeta-minus Decay100.00%
Isomeric Transition< 0.02%
24723.0 minutesBeta-minus Decay100.00%
248≈ 10 minutesBeta-minus Decay100.00%
249No Data AvailableBeta-minus Decay (suspected)No Data Available