Isotopes of einsteinium

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Isotopes of einsteinium  (99Es)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
252Es synth 471.7 d α 248Bk
ε 252Cf
β 252Fm
253Essynth20.47 dα 249Bk
SF
254Essynth275.7 dε 254Cf
β 254Fm
α 250Bk
255Essynth39.8 dβ 255Fm
α 251Bk
SF

Einsteinium (99Es) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be discovered (in nuclear fallout from the Ivy Mike H-bomb test) was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 8 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

List of isotopes


Nuclide
[n 1]
Z N Isotopic mass (Da) [2]
[n 2] [n 3]
Half-life [1]
Decay
mode
[1]
[n 4]
Daughter
isotope

Spin and
parity [1]
[n 5] [n 6]
Excitation energy [n 6]
240Es99141240.06895(39)#6.0(17) s α (70%)236Bk4−#
β+ (30%)240Cf
β+, SF (0.16%)(various)
241Es99142241.06859(25)#4.3+2.4
−1.2
 s
[3]
α237Bk3/2−#
242Es [4] 99143242.06957(28)#16.9(8) sβ+242Cf2+#
α (41%)238Bk
β+, SF (1.5%)(various)
243Es99144243.06951(22)#22.1(14) sα (61%)239Bk(7/2+)
β+? (39%)243Cf
243mEs [n 7] 50(50)# keV>50# μs IT?243Es3/2−#
α?239Bk
β+?243Cf
244Es99145244.07088(20)#37(4) sβ+ (95%)244Cf6+#
α (5%)240Bk
β+, SF (0.011%)(various)
245Es99146245.07119(18)#1.11(6) minβ+ (51%)245Cf(3/2−)
α (49%)241Bk
245mEs [n 7] 30(15)# keV>50# μs IT?245Es7/2+#
α?241Bk
β+?245Cf
246Es99147246.07281(10)7.5(5) minβ+ (90.1%)246Cf4−#
α (9.9%)242Bk
β+, SF (0.003%)(various)
247Es99148247.073622(21)4.55(26) minβ+ (93%)247Cf(7/2+)
α (7%)243Bk
247mEs [n 7] 50(50)# keV>20# μsIT?247Es(3/2−)
α?243Bk
β+247Cf
248Es99149248.07547(6)#24(3) minβ+ (99.75%)248Cf2−#
α (0.25%)244Bk
β+, SF (3.5×10−4%)(various)
249Es99150249.07641(3)#102.2(6) minβ+ (99.43%)249Cf7/2+
α (0.57%)245Bk
250Es99151250.07861(11)#8.6(1) hβ+250Cf6(+)
250mEs [n 7] 200(150)# keV2.22(5) hβ+250Cf1(−)
251Es99152251.079991(6)33(1) h EC (99.5%)251Cf3/2−
α (0.5%)247Bk
251mEs8.4(10) keV>200# μsIT?251Es(7/2+)
EC?251Cf
252Es99153252.08298(5)471.7(19) dα (78%)248Bk(4+)
EC (22%)252Cf
253Es [n 8] 99154253.0848212(13)20.47(3) dα249Bk7/2+
SF (8.7×10−6%)(various)
253mEs106(4) keV>10# μsIT?253Es3/2−#
254Es99155254.088024(3)275.7(5) dα [n 9] 250Bk7+
β (1.74×10−4%)254Fm
SF (<3×10−6%)(various)
254mEs80.4(11) keV39.3(2) hβ (98%)254Fm2+
IT (<3%)254Es
α (0.32%)250Bk
EC (0.076%)254Cf
SF (<0.045%)(various)
255Es99156255.090274(12)39.8(12) dβ (92.0%)255Fm(7/2+)
α (8.0%)251Bk
SF (0.0041%)(various)
256Es99157256.09360(11)#7.6 hβ256Fm7+#
β, SF (0.002%)(various)
256mEs [n 7] 0(100)# keV25.4(12) minβ256Fm0+#
257Es99158257.09598(44)#7.7(2) dβ257Fm7/2+#
This table header & footer:
  1. mEs  Excited nuclear isomer.
  2. ()  Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. #  Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    SF: Spontaneous fission
  5. () spin value  Indicates spin with weak assignment arguments.
  6. 1 2 #  Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. 1 2 3 4 5 Order of ground state and isomer is uncertain.
  8. Most common isotope
  9. Theoretically capable of electron capture to 254Cf [1]

References

  1. 1 2 3 4 5 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.
  2. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  3. Khuyagbaatar, J.; Albers, H. M.; Block, M.; Brand, H.; Cantemir, R. A.; Di Nitto, A.; Düllmann, Ch. E.; Götz, M.; Götz, S.; Heßberger, F. P.; Jäger, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Lommel, B.; Lens, L.; Mistry, A.; Schausten, B.; Uusitalo, J.; Yakushev, A. (1 October 2020). "Search for Electron-Capture Delayed Fission in the New Isotope 244Md". Physical Review Letters. 125 (14): 142504. Bibcode:2020PhRvL.125n2504K. doi:10.1103/PhysRevLett.125.142504. PMID   33064498. S2CID   223546973.
  4. Khuyagbaatar, J.; Cantemir, R. A.; Düllmann, Ch. E.; Jäger, E.; Kindler, B.; Krier, J.; Kurz, N.; Lommel, B.; Schausten, B.; Yakushev, A. (2024-03-18). "Decay properties of the neutron-deficient isotope Es 242". Physical Review C. 109 (3). arXiv: 2408.01714 . doi:10.1103/PhysRevC.109.034311. ISSN   2469-9985.