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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 Es in 1952. There are 18 known radioisotopes from Es to Es, and 4 nuclear isomers. The longest-lived isotope is Es with a half-life of 471.7 days, or around 1.293 years.
List of isotopes
Nuclide |
Z | N | Isotopic mass (Da) |
Half-life |
Decay mode |
Daughter isotope |
Spin and parity | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy | |||||||||||||||||||
Es | 99 | 141 | 240.06895(39)# | 6.0(17) s | α (70%) | Bk | 4−# | ||||||||||||
β (30%) | Cf | ||||||||||||||||||
β, SF (0.16%) | (various) | ||||||||||||||||||
Es | 99 | 142 | 241.06859(25)# | 4.3+2.4 −1.2 s |
α | Bk | 3/2−# | ||||||||||||
β? | Cf | ||||||||||||||||||
Es | 99 | 143 | 242.06957(28)# | 16.9(8) s | β | Cf | 2+# | ||||||||||||
α (41%) | Bk | ||||||||||||||||||
β, SF (1.5%) | (various) | ||||||||||||||||||
Es | 99 | 144 | 243.06951(22)# | 22.1(14) s | α (61%) | Bk | (7/2+) | ||||||||||||
β (39%) | Cf | ||||||||||||||||||
Es | 99 | 145 | 244.07088(20)# | 37(4) s | β (95%) | Cf | 6+# | ||||||||||||
α (5%) | Bk | ||||||||||||||||||
β, SF (0.011%) | (various) | ||||||||||||||||||
Es | 99 | 146 | 245.07119(18)# | 1.11(6) min | β (51%) | Cf | (3/2−) | ||||||||||||
α (49%) | Bk | ||||||||||||||||||
Es | 30(15)# keV | >50# μs | IT? | Es | 7/2+# | ||||||||||||||
α? | Bk | ||||||||||||||||||
β? | Cf | ||||||||||||||||||
Es | 99 | 147 | 246.072806(97) | 7.5(5) min | β (90.1%) | Cf | 4−# | ||||||||||||
α (9.9%) | Bk | ||||||||||||||||||
β, SF (.003%) | (various) | ||||||||||||||||||
Es | 99 | 148 | 247.073622(21) | 4.55(26) min | β (93%) | Cf | (7/2+) | ||||||||||||
α (7%) | Bk | ||||||||||||||||||
SF? | (various) | ||||||||||||||||||
Es | 99 | 149 | 248.075469(56)# | 24(3) min | β (99.75%) | Cf | 2−# | ||||||||||||
α (.25%) | Bk | ||||||||||||||||||
β, SF (3.5×10%) | (various) | ||||||||||||||||||
Es | 99 | 150 | 249.076409(32)# | 102.2(6) min | β (99.43%) | Cf | 7/2+ | ||||||||||||
α (.57%) | Bk | ||||||||||||||||||
Es | 99 | 151 | 250.07861(11)# | 8.6(1) h | β | Cf | 6(+) | ||||||||||||
α? | Bk | ||||||||||||||||||
Es | 200(150)# keV | 2.22(5) h | β | Cf | 1(−) | ||||||||||||||
α? | Bk | ||||||||||||||||||
Es | 99 | 152 | 251.0799914(57) | 33(1) h | EC (99.5%) | Cf | 3/2− | ||||||||||||
α (.5%) | Bk | ||||||||||||||||||
Es | 99 | 153 | 252.082979(54) | 471.7(19) d | α (78(2)%) | Bk | (4+) | ||||||||||||
EC (22(2)%) | Cf | ||||||||||||||||||
Es | 99 | 154 | 253.0848212(13) | 20.47(3) d | α | Bk | 7/2+ | ||||||||||||
SF (8.7×10%) | (various) | ||||||||||||||||||
Es | 99 | 155 | 254.0880243(32) | 275.7(5) d | α | Bk | 7+ | ||||||||||||
β (1.74×10%) | Fm | ||||||||||||||||||
SF (<3×10%) | (various) | ||||||||||||||||||
Es | 80.4(11) keV | 39.3(2) h | β (98(2)%) | Fm | 2+ | ||||||||||||||
IT (<3%) | Es | ||||||||||||||||||
α (0.32(1)%) | Bk | ||||||||||||||||||
EC (0.076(7)%) | Cf | ||||||||||||||||||
SF (<0.045%) | (various) | ||||||||||||||||||
Es | 99 | 156 | 255.090274(12) | 39.8(12) d | β (92.0%) | Fm | (7/2+) | ||||||||||||
α (8.0%) | Bk | ||||||||||||||||||
SF (.0041%) | (various) | ||||||||||||||||||
Es | 99 | 157 | 256.09360(11)# | 7.6 h | β | Fm | 7+# | ||||||||||||
β, SF (.002%) | (various) | ||||||||||||||||||
Es | 0(100)# keV | 25.4(12) min | β | Fm | 0+# | ||||||||||||||
Es | 99 | 158 | 257.09598(44)# | 7.7(2) d | β | Fm | 7/2+# | ||||||||||||
α? | Bk | ||||||||||||||||||
This table header & footer: |
- Es – Excited nuclear isomer.
- ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
-
Modes of decay:
EC: Electron capture IT: Isomeric transition SF: Spontaneous fission - ( ) spin value – Indicates spin with weak assignment arguments.
- ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^ Order of ground state and isomer is uncertain.
- Most common isotope
- Theoretically capable of electron capture to Cf
References
- ^ 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.
- 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.
- 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 Md". Physical Review Letters. 125 (14): 142504. Bibcode:2020PhRvL.125n2504K. doi:10.1103/PhysRevLett.125.142504. PMID 33064498. S2CID 223546973.
- 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.
- Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.