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 4 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.
List of isotopes
| Nuclide1 | Z | N | Isotopic mass (Da)234 | Half-life5 | Decaymode67 | Daughterisotope | Spin andparity8910 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy11 | |||||||||||||||||||
| 240Es | 99 | 141 | 240.06895(39)# | 6.0(17) s | α (70%) | 236Bk | 4−# | ||||||||||||
| β+ (30%) | 240Cf | ||||||||||||||||||
| β+, SF (0.16%) | (various) | ||||||||||||||||||
| 241Es12 | 99 | 142 | 241.06859(25)# | 4.3+2.4−1.2 s | α | 237Bk | 3/2−# | ||||||||||||
| β+? | 241Cf | ||||||||||||||||||
| 242Es13 | 99 | 143 | 242.06957(28)# | 16.9(8) s | β+ | 242Cf | 2+# | ||||||||||||
| α (41%) | 238Bk | ||||||||||||||||||
| β+, SF (1.5%) | (various) | ||||||||||||||||||
| 243Es | 99 | 144 | 243.06951(22)# | 22.1(14) s | α (61%) | 239Bk | (7/2+) | ||||||||||||
| β+ (39%) | 243Cf | ||||||||||||||||||
| 244Es | 99 | 145 | 244.07088(20)# | 37(4) s | β+ (95%) | 244Cf | 6+# | ||||||||||||
| α (5%) | 240Bk | ||||||||||||||||||
| β+, SF (0.011%) | (various) | ||||||||||||||||||
| 245Es | 99 | 146 | 245.07119(18)# | 1.11(6) min | β+ (51%) | 245Cf | (3/2−) | ||||||||||||
| α (49%) | 241Bk | ||||||||||||||||||
| 245mEs14 | 30(15)# keV | >50# μs | IT? | 245Es | 7/2+# | ||||||||||||||
| α? | 241Bk | ||||||||||||||||||
| β+? | 245Cf | ||||||||||||||||||
| 246Es | 99 | 147 | 246.072806(97) | 7.5(5) min | β+ (90.1%) | 246Cf | 4−# | ||||||||||||
| α (9.9%) | 242Bk | ||||||||||||||||||
| β+, SF (.003%) | (various) | ||||||||||||||||||
| 247Es | 99 | 148 | 247.073622(21) | 4.55(26) min | β+ (93%) | 247Cf | (7/2+) | ||||||||||||
| α (7%) | 243Bk | ||||||||||||||||||
| SF? | (various) | ||||||||||||||||||
| 248Es | 99 | 149 | 248.075469(56)# | 24(3) min | β+ (99.75%) | 248Cf | 2−# | ||||||||||||
| α (.25%) | 244Bk | ||||||||||||||||||
| β+, SF (3.5×10−4%) | (various) | ||||||||||||||||||
| 249Es | 99 | 150 | 249.076409(32)# | 102.2(6) min | β+ (99.43%) | 249Cf | 7/2+ | ||||||||||||
| α (.57%) | 245Bk | ||||||||||||||||||
| 250Es | 99 | 151 | 250.07861(11)# | 8.6(1) h | β+ | 250Cf | 6(+) | ||||||||||||
| α? | 246Bk | ||||||||||||||||||
| 250mEs15 | 200(150)# keV | 2.22(5) h | β+ | 250Cf | 1(−) | ||||||||||||||
| α? | 246Bk | ||||||||||||||||||
| 251Es | 99 | 152 | 251.0799914(57) | 33(1) h | EC (99.5%) | 251Cf | 3/2− | ||||||||||||
| α (.5%) | 247Bk | ||||||||||||||||||
| 252Es | 99 | 153 | 252.082979(54) | 471.7(19) d | α (78(2)%) | 248Bk | (4+) | ||||||||||||
| EC (22(2)%) | 252Cf | ||||||||||||||||||
| 253Es16 | 99 | 154 | 253.0848212(13) | 20.47(3) d | α | 249Bk | 7/2+ | ||||||||||||
| SF (8.7×10−6%) | (various) | ||||||||||||||||||
| 254Es | 99 | 155 | 254.0880243(32) | 275.7(5) d | α17 | 250Bk | 7+ | ||||||||||||
| β− (1.74×10−4%) | 254Fm | ||||||||||||||||||
| SF (<3×10−6%) | (various) | ||||||||||||||||||
| 254mEs | 80.4(11) keV | 39.3(2) h | β− (98(2)%) | 254Fm | 2+ | ||||||||||||||
| IT (<3%) | 254Es | ||||||||||||||||||
| α (0.32(1)%) | 250Bk | ||||||||||||||||||
| EC (0.076(7)%) | 254Cf | ||||||||||||||||||
| SF (<0.045%) | (various) | ||||||||||||||||||
| 255Es | 99 | 156 | 255.090274(12) | 39.8(12) d | β− (92.0%) | 255Fm | (7/2+) | ||||||||||||
| α (8.0%) | 251Bk | ||||||||||||||||||
| SF (.0041%) | (various) | ||||||||||||||||||
| 256Es | 99 | 157 | 256.09360(11)# | 7.6 h | β− | 256Fm | 7+# | ||||||||||||
| β−, SF (.002%) | (various) | ||||||||||||||||||
| 256mEs18 | 0(100)# keV | 25.4(12) min | β− | 256Fm | 0+# | ||||||||||||||
| 257Es | 99 | 158 | 257.09598(44)# | 7.7(2) d | β− | 257Fm | 7/2+# | ||||||||||||
| α? | 253Bk | ||||||||||||||||||
This table header & footer:
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- 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.
References
mEs – Excited nuclear isomer. /wiki/Nuclear_isomer ↩
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. /wiki/Doi_(identifier) ↩
( ) – 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). ↩
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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩
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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩
Modes of decay: EC:Electron captureIT:Isomeric transitionSF:Spontaneous fission /wiki/Electron_capture ↩
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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩
( ) 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). ↩
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). ↩
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. http://urn.fi/URN:NBN:fi:jyu-202010066084 ↩
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. /wiki/ArXiv_(identifier) ↩
Order of ground state and isomer is uncertain. ↩
Order of ground state and isomer is uncertain. ↩
Most common isotope ↩
Theoretically capable of electron capture to 254Cf[1] ↩
Order of ground state and isomer is uncertain. ↩