Isotopes of curium
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Curium(96Cm) is anartificial elementwith an atomic number of 96. Because it is an artificial element, astandard atomic weightcannot be given, and it has nostable isotopes.The firstisotopesynthesized was242Cm in 1944, which has 146 neutrons.
There are 19 knownradioisotopesranging from233Cm to251Cm. There are also ten knownnuclear isomers.The longest-lived isotope is247Cm, withhalf-life15.6 million years – orders of magnitude longer than that of any known isotope beyond curium, and long enough to study as a possibleextinct radionuclidethat would be produced by ther-process.[2][3]The longest-lived isomer is246mCm with a half-life of 1.12 seconds.
List of isotopes
[edit]
Nuclide [n 1] |
Z | N | Isotopic mass(Da) [n 2][n 3] |
Half-life [n 4] |
Decay mode [n 5] |
Daughter isotope |
Spinand parity [n 6][n 4] | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy[n 4] | |||||||||||||||||||
233Cm | 96 | 137 | 233.05077(8) | 23+13 −6s |
β+(80%) | 233Am | 3/2+# | ||||||||||||
α(20%) | 229Pu | ||||||||||||||||||
234Cm | 96 | 138 | 234.05016(2) | 52(9) s | β+(71%) | 234Am | 0+ | ||||||||||||
α (27%) | 230Pu | ||||||||||||||||||
SF (2%) | (various) | ||||||||||||||||||
235Cm[4] | 96 | 139 | 235.05143(22)# | 300+250 −100s |
β+(99.0%) | 235Am | (5/2+) | ||||||||||||
α (1.0%) | 231Pu | ||||||||||||||||||
236Cm | 96 | 140 | 236.05141(22)# | 6.8(8) min | β+(82%) | 236Am | 0+ | ||||||||||||
α (18%) | 232Pu | ||||||||||||||||||
SF (<0.1%)[5] | (various) | ||||||||||||||||||
237Cm[6][4] | 96 | 141 | 237.05290(22)# | >660 s | β+ | 237Am | (5/2+) | ||||||||||||
α (<1%) | 233Pu | ||||||||||||||||||
238Cm[6] | 96 | 142 | 238.05303(4) | 2.2(4) h | EC(~94%) | 238Am | 0+ | ||||||||||||
α (~6%) | 234Pu | ||||||||||||||||||
239Cm[1] | 96 | 143 | 239.05496(11)# | 2.5(4) h | β+ | 239Am | (7/2−) | ||||||||||||
α (6.2x10−3%) | 235Pu | ||||||||||||||||||
240Cm | 96 | 144 | 240.0555295(25) | 27(1) d | α (99.5%) | 236Pu | 0+ | ||||||||||||
EC (.5%) | 240Am | ||||||||||||||||||
SF(3.9×10−6%) | (various) | ||||||||||||||||||
241Cm | 96 | 145 | 241.0576530(23) | 32.8(2) d | EC (99%) | 241Am | 1/2+ | ||||||||||||
α (1%) | 237Pu | ||||||||||||||||||
242Cm[n 7] | 96 | 146 | 242.0588358(20) | 162.8(2) d | α[n 8] | 238Pu | 0+ | ||||||||||||
SF (6.33×10−6%) | (various) | ||||||||||||||||||
CD(10−14%)[n 9] | 208Pb 34Si | ||||||||||||||||||
242mCm | 2800(100) keV | 180(70) ns | |||||||||||||||||
243Cm | 96 | 147 | 243.0613891(22) | 29.1(1) y | α (99.71%) | 239Pu | 5/2+ | ||||||||||||
EC (.29%) | 243Am | ||||||||||||||||||
SF (5.3×10−9%) | (various) | ||||||||||||||||||
243mCm | 87.4(1) keV | 1.08(3) μs | IT | 243Cm | 1/2+ | ||||||||||||||
244Cm[n 7] | 96 | 148 | 244.0627526(20) | 18.10(2) y | α | 240Pu | 0+ | ||||||||||||
SF (1.34×10−4%) | (various) | ||||||||||||||||||
244m1Cm | 1040.188(12) keV | 34(2) ms | IT | 244Cm | 6+ | ||||||||||||||
244m2Cm | 1100(900)# keV | >500 ns | SF | (various) | |||||||||||||||
245Cm | 96 | 149 | 245.0654912(22) | 8.5(1)×103y | α | 241Pu | 7/2+ | ||||||||||||
SF (6.1×10−7%) | (various) | ||||||||||||||||||
245mCm | 355.92(10) keV | 290(20) ns | IT | 245Cm | 1/2+ | ||||||||||||||
246Cm | 96 | 150 | 246.0672237(22) | 4.76(4)×103y | α (99.97%) | 242Pu | 0+ | ||||||||||||
SF (.0261%) | (various) | ||||||||||||||||||
246mCm | 1179.66(13) keV | 1.12(0.24) s | IT | 246Cm | 8− | ||||||||||||||
247Cm | 96 | 151 | 247.070354(5) | 1.56(5)×107y | α | 243Pu | 9/2− | ||||||||||||
247m1Cm | 227.38(19) keV | 26.3(0.3) μs | IT | 247Cm | 5/2+ | ||||||||||||||
247m2Cm | 404.90(3) keV | 100.6(0.6) ns | IT | 247Cm | 1/2+ | ||||||||||||||
248Cm | 96 | 152 | 248.072349(5) | 3.48(6)×105y | α (91.74%) | 244Pu | 0+ | ||||||||||||
SF (8.26%) | (various) | ||||||||||||||||||
248mCm | 1458.1(1) keV | 146(18) μs | IT | 248Cm | (8−) | ||||||||||||||
249Cm | 96 | 153 | 249.075953(5) | 64.15(3) min | β− | 249Bk | 1/2(+) | ||||||||||||
249mCm | 48.758(17) keV | 23 μs | α | 245Pu | (7/2+) | ||||||||||||||
250Cm | 96 | 154 | 250.078357(12) | 8300# y | SF (74%)[n 10] | (various) | 0+ | ||||||||||||
α (18%) | 246Pu | ||||||||||||||||||
β−(8%) | 250Bk | ||||||||||||||||||
251Cm | 96 | 155 | 251.082285(24) | 16.8(2) min | β− | 251Bk | (1/2+) | ||||||||||||
This table header & footer: |
- ^mCm – Excitednuclear 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).
- ^abc# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
Modes of decay:
CD: Cluster decay EC: Electron capture SF: Spontaneous fission - ^( ) spin value – Indicates spin with weak assignment arguments.
- ^abMost common isotopes
- ^Theoretically capable of β+β+decay to242Pu[1]
- ^Heaviest known nuclide to undergocluster decay
- ^The nuclide with the lowestatomic numberknown to undergospontaneous fissionas the main decay mode
Actinides vs fission products
[edit]Actinides[7]bydecay chain | Half-life range (a) |
Fission productsof235Ubyyield[8] | ||||||
---|---|---|---|---|---|---|---|---|
4n | 4n+ 1 | 4n+ 2 | 4n+ 3 | 4.5–7% | 0.04–1.25% | <0.001% | ||
228Ra№ | 4–6 a | 155Euþ | ||||||
248Bk[9] | > 9 a | |||||||
244Cmƒ | 241Puƒ | 250Cf | 227Ac№ | 10–29 a | 90Sr | 85Kr | 113mCdþ | |
232Uƒ | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs | 151Smþ | 121mSn | ||
249Cfƒ | 242mAmƒ | 141–351 a |
No fission products have ahalf-life | |||||
241Amƒ | 251Cfƒ[10] | 430–900 a | ||||||
226Ra№ | 247Bk | 1.3–1.6 ka | ||||||
240Pu | 229Th | 246Cmƒ | 243Amƒ | 4.7–7.4 ka | ||||
245Cmƒ | 250Cm | 8.3–8.5 ka | ||||||
239Puƒ | 24.1 ka | |||||||
230Th№ | 231Pa№ | 32–76 ka | ||||||
236Npƒ | 233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126Sn | |||
248Cm | 242Pu | 327–375 ka | 79Se₡ | |||||
1.33 Ma | 135Cs₡ | |||||||
237Npƒ | 1.61–6.5 Ma | 93Zr | 107Pd | |||||
236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
244Pu | 80 Ma |
... nor beyond 15.7 Ma[11] | ||||||
232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
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References
[edit]- ^abcKondev, 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.
- ^Côté, Benoit; Eichler, Marius; Yagüe López, Andrés; Vassh, Nicole; Mumpower, Matthew R.; Világos, Blanka; Soós, Benjámin;Arcones, Almudena;Sprouse, Trevor M.; Surman, Rebecca; Pignatari, Marco; Pető, Mária K.; Wehmeyer, Benjamin; Rauscher, Thomas; Lugaro, Maria (26 February 2021). "129I and247Cm in meteorites constrain the last astrophysical source of solar r-process elements ".Science.371(6532): 945–948.arXiv:2006.04833.Bibcode:2021Sci...371..945C.doi:10.1126/science.aba1111.PMID33632846.S2CID232050526.
- ^Davis, A.M.; McKeegan, K.D. (2014). "Short-Lived Radionuclides and Early Solar System Chronology".Treatise on Geochemistry:383.doi:10.1016/B978-0-08-095975-7.00113-3.ISBN9780080983004.
- ^abKhuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K. (12 October 2020)."α decay of Fm 243 143 and Fm 245 145, and of their daughter nuclei".Physical Review C.102(4): 044312.doi:10.1103/PhysRevC.102.044312.ISSN2469-9985.S2CID241259726.Retrieved24 June2023.
- ^Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Comas, V. S.; Heinz, S.; Heredia, J. A.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Nishio, K.; Yakushev, A. (1 October 2010)."The new isotope236Cm and new data on233Cm and237, 238, 240Cf "(PDF).The European Physical Journal A.46(1): 59–67.Bibcode:2010EPJA...46...59K.doi:10.1140/epja/i2010-11026-9.ISSN1434-601X.S2CID122809010.Retrieved24 June2023.
- ^abAsai, M.; Tsukada, K.; Ichikawa, S.; Sakama, M.; Haba, H.; Nishinaka, I.; Nagame, Y.; Goto, S.; Kojima, Y.; Oura, Y.; Shibata, M. (20 June 2006)."α decay of238Cm and the new isotope237Cm ".Physical Review C.73(6): 067301.doi:10.1103/PhysRevC.73.067301.Retrieved24 June2023.
- ^Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability afterpolonium(84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap isradon-222with a half life of less than fourdays). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
- ^Specifically fromthermal neutronfission of uranium-235, e.g. in a typicalnuclear reactor.
- ^Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248".Nuclear Physics.71(2): 299.Bibcode:1965NucPh..71..299M.doi:10.1016/0029-5582(65)90719-4.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248with a half-life greater than 9 [years]. No growth of Cf248was detected, and a lower limit for the β−half-life can be set at about 104[years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]. " - ^This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
- ^Excluding those "classically stable"nuclides with half-lives significantly in excess of232Th; e.g., while113mCd has a half-life of only fourteen years, that of113Cd is eightquadrillionyears.
- Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean;Wapstra, Aaldert Hendrik(2003),"The NUBASEevaluation 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 NUBASEevaluation 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.ISBN978-0-8493-0485-9.