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Einsteinium

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Isotopes of the Element Fermium

[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.

Known Isotopes

Mass NumberHalf-lifeDecay ModeBranching Percentage
2410.73 millisecondsSpontaneous Fission> 78.00%
Alpha Decay< 14.00%
Electron Capture< 12.00%
242< 4 microsecondsSpontaneous Fission<= 100.00%
243231 millisecondsAlpha Decay91.00%
Spontaneous Fission9.00%
Electron Capture< 10.00%
2443.12 millisecondsAlpha Decay< 1.00%
Spontaneous Fission> 97.00%
Electron Capture< 2.00%
2454.2 secondsAlpha Decay<= 100.00%
2461.54 secondsAlpha Decay93.20%
Spontaneous Fission6.80%
Electron Capture<= 1.30%
24731 secondsAlpha Decay>= 84.00%
Electron Capture<= 16.00%
247m5.1 secondsAlpha Decay84.00%
24836 secondsAlpha Decay93.00%
Electron Capture7.00%
Spontaneous Fission0.10%
2492.6 minutesElectron Capture67.00%
Alpha Decay33.00%
25030 minutesAlpha Decay> 90.00%
Electron Capture< 10.00%
Spontaneous Fission6.9×10-3 %
250m1.93 secondsIsomeric Transition100.00%
2515.30 hoursElectron Capture98.20%
Alpha Decay1.80%
25225.39 hoursSpontaneous Fission2.3×10-3 %
Alpha Decay100.00%
2533.00 daysElectron Capture88.00%
Alpha Decay12.00%
2543.240 hoursAlpha Decay99.94%
Spontaneous Fission0.06%
25520.07 hoursAlpha Decay100.00%
Spontaneous Fission2.4×10-5 %
256157.6 minutesSpontaneous Fission91.90%
Alpha Decay8.10%
257100.5 daysAlpha Decay99.79%
Spontaneous Fission0.21%
258370 microsecondsSpontaneous Fission<= 100.00%
2591.5 secondsSpontaneous Fission100.00%
260≈ 4 millisecondsSpontaneous Fission100.00%