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 d SF –
α 249Bk
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 5 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)
241Es [3] 99142241.06859(25)#4.3+2.4
−1.2 s		α237Bk3/2−#
β+?241Cf
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
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
245m1Es30(15)# keV>50# us IT?245Es7/2+#
α?241Bk
β+?245Cf
245m2Es283(15)# keVIT245Es(7/2−)
246Es99147246.072806(97)7.5(5) minβ+ (90.1%)246Cf4−#
α (9.9%)242Bk
β+, SF (.003%)(various)
247Es99148247.073622(21)4.55(26) minβ+ (93%)247Cf(7/2+)
α (7%)243Bk
SF?(various)
248Es99149248.075469(56)#24(3) minβ+ (99.75%)248Cf2−#
α (.25%)244Bk
β+, SF (3.5×10−4%)(various)
249Es99150249.076409(32)#102.2(6) minβ+ (99.43%)249Cf7/2+
α (.57%)245Bk
250Es99151250.07861(11)#8.6(1) hβ+250Cf6(+)
α?246Bk
250mEs200(150)# keV2.22(5) hβ+250Cf1(−)
α?246Bk
251Es99152251.0799914(57)33(1) h EC (99.5%)251Cf3/2−
α (.5%)247Bk
252Es99153252.082979(54)471.7(19) dα (78(2)%)248Bk(4+)
EC (22(2)%)252Cf
253Es [n 7] 99154253.0848212(13)20.47(3) dα249Bk7/2+
SF (8.7×10−6%)(various)
254Es99155254.0880243(32)275.7(5) dα250Bk7+
β− (1.74×10−4%)254Fm
SF (<3×10−6%)(various)
EC?254Cf
254mEs80.4(11) keV39.3(2) hβ− (98(2)%)254Fm2+
IT (<3%)254Es
α (0.32(1)%)250Bk
EC (0.076(7)%)254Cf
SF (<0.045%)(various)
255Es99156255.090274(12)39.8(12) dβ− (92.0%)255Fm(7/2+)
α (8.0%)251Bk
SF (.0041%)(various)
256Es99157256.09360(11)#7.6 hβ−256Fm7+#
β−, SF (.002%)(various)
256mEs0(100)# keV25.4(12) minβ−256Fm0+#
257Es99158257.09598(44)#7.7(2) dβ−257Fm7/2+#
α?253Bk
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. ↑ Most common isotope

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References

  1. 1 2 3 4 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). doi:10.1103/PhysRevC.109.034311. ISSN   2469-9985.
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