Isotopes of curium

Isotopes of curium (₉₆Cm)
SF	–
34Si	208Pb
ε	243Am
SF	–
SF	–
SF	–
SF	–
SF	–
α	246Pu
β−	250Bk

Curium (₉₆Cm) is an artificial element with an atomic number of 96. Because it is an artificial element, a standard atomic weight cannot be given, and it has no stable isotopes. The first isotope synthesized was ²⁴²Cm in 1944, which has 146 neutrons.

There are 19 known radioisotopes ranging from ²³³Cm to ²⁵¹Cm. There are also ten known nuclear isomers. The longest-lived isotope is ²⁴⁷Cm, with half-life 15.6 million years – orders of magnitude longer than that of any known isotope beyond curium, and long enough to study as a possible extinct radionuclide that would be produced by the r-process.[2][3] The longest-lived isomer is ^246mCm with a half-life of 1.12 seconds.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope	Spin and parity [n 6][n 4]
Nuclide [n 1]	Excitation energy[n 4]			Half-life [n 4]	Decay mode [n 5]	Daughter isotope	Spin and parity [n 6][n 4]
²³³Cm	96	137	233.05077(8)	23+13 −6 s	β⁺ (80%)	²³³Am	3/2+#
²³³Cm	96	137	233.05077(8)	23+13 −6 s	α (20%)	²²⁹Pu	3/2+#
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 −100 s	β⁺ (99.0%)	²³⁵Am	(5/2+)
²³⁵Cm[4]	96	139	235.05143(22)#	300+250 −100 s	α (1.0%)	²³¹Pu	(5/2+)
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+)
²³⁷Cm[6][4]	96	141	237.05290(22)#	>660 s	α (<1%)	²³³Pu	(5/2+)
²³⁸Cm[6]	96	142	238.05303(4)	2.2(4) h	EC (~94%)	²³⁸Am	0+
²³⁸Cm[6]	96	142	238.05303(4)	2.2(4) h	α (~6%)	²³⁴Pu	0+
²³⁹Cm[1]	96	143	239.05496(11)#	2.5(4) h	β⁺	²³⁹Am	(7/2−)
²³⁹Cm[1]	96	143	239.05496(11)#	2.5(4) h	α (6.2x10⁻³%)	²³⁵Pu	(7/2−)
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+
²⁴¹Cm	96	145	241.0576530(23)	32.8(2) d	α (1%)	²³⁷Pu	1/2+
²⁴²Cm[n 7]	96	146	242.0588358(20)	162.8(2) d	α	²³⁸Pu	0+
					SF (6.33×10⁻⁶%)	(various)
					CD (10⁻¹⁴%)[n 8]	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+
²⁴⁴Cm[n 7]	96	148	244.0627526(20)	18.10(2) y	SF (1.34×10⁻⁴%)	(various)	0+
^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)×10³ y	α	²⁴¹Pu	7/2+
²⁴⁵Cm	96	149	245.0654912(22)	8.5(1)×10³ y	SF (6.1×10⁻⁷%)	(various)	7/2+
^245mCm	355.92(10) keV			290(20) ns	IT	²⁴⁵Cm	1/2+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)×10³ y	α (99.97%)	²⁴²Pu	0+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)×10³ y	SF (.0261%)	(various)	0+
^246mCm	1179.66(13) keV			1.12(0.24) s	IT	²⁴⁶Cm	8-
²⁴⁷Cm	96	151	247.070354(5)	1.56(5)×10⁷ y	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)×10⁵ y	α (91.74%)	²⁴⁴Pu	0+
²⁴⁸Cm	96	152	248.072349(5)	3.48(6)×10⁵ y	SF (8.26%)	(various)	0+
^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 9]	(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 – 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).
# – 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.
Most common isotopes
Heaviest known nuclide to undergo cluster decay
The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode

Actinides vs fission products

Actinides and fission products by half-life
Actinides[7] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield[8]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29 a	⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a	¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
²⁴⁸Bk[9]	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have a half-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ[10]	430–900 a
		²²⁶Ra^№	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7–7.4 ka
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3–8.5 ka
			²³⁹Pu^ƒ	24.1 ka
		²³⁰Th^№	²³¹Pa^№	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150–250 ka	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327–375 ka		⁷⁹Se^₡
				1.53 Ma	⁹³Zr
	²³⁷Np^ƒ			2.1–6.5 Ma	¹³⁵Cs^₡	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15–24 Ma		¹²⁹I^₡
²⁴⁴Pu				80 Ma	... nor beyond 15.7 Ma[11]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma[11]
₡, has thermal neutron capture cross section in the range of 8–50 barns ƒ, fissile №, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

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.
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). "129 I and 247 Cm in meteorites constrain the last astrophysical source of solar r-process elements". Science. 371 (6532): 945–948. arXiv:2006.04833. doi:10.1126/science.aba1111. PMID 33632846. S2CID 232050526.
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. ISBN 9780080983004.
Khuyagbaatar, 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). doi:10.1103/PhysRevC.102.044312. ISSN 2469-9985. Retrieved 24 June 2023.
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 isotope 236Cm and new data on 233Cm and 237, 238, 240Cf" (PDF). The European Physical Journal A. 46 (1): 59–67. doi:10.1140/epja/i2010-11026-9. ISSN 1434-601X. Retrieved 24 June 2023.
Asai, 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 of 238Cm and the new isotope 237Cm". Physical Review C. 73 (6): 067301. doi:10.1103/PhysRevC.73.067301. Retrieved 24 June 2023.
Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear 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 Bk²⁴⁸ with a half-life greater than 9 [years]. No growth of Cf²⁴⁸ was 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 of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is nearly eight quadrillion years.

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
Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.

"News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
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.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[4] Cm – Excited nuclear isomer.

[5] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-6] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-7] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[8] Modes of decay:

CD: Cluster decay

EC: Electron capture

SF: Spontaneous fission

[9] ( ) spin value – Indicates spin with weak assignment arguments.

[c-13] Most common isotopes

[14] Heaviest known nuclide to undergo cluster decay

[15] The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode

[NUBASE2020-1] 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.

[Cm-Côté-2] 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). "129 I and 247 Cm in meteorites constrain the last astrophysical source of solar r-process elements". Science. 371 (6532): 945–948. arXiv:2006.04833. doi:10.1126/science.aba1111. PMID 33632846. S2CID 232050526.

[Cm-Davis-3] 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. ISBN 9780080983004.

[243Fm,245Fm-10] Khuyagbaatar, 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). doi:10.1103/PhysRevC.102.044312. ISSN 2469-9985. Retrieved 24 June 2023.

[11] 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 isotope 236Cm and new data on 233Cm and 237, 238, 240Cf" (PDF). The European Physical Journal A. 46 (1): 59–67. doi:10.1140/epja/i2010-11026-9. ISSN 1434-601X. Retrieved 24 June 2023.

[237Cm,238Cm-12] Asai, 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 of 238Cm and the new isotope 237Cm". Physical Review C. 73 (6): 067301. doi:10.1103/PhysRevC.73.067301. Retrieved 24 June 2023.

[16] Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.

[17] Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.

[18] 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 Bk²⁴⁸ with a half-life greater than 9 [years]. No growth of Cf²⁴⁸ was 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]."

[19] This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".

[20] Excluding those "classically stable" nuclides with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is nearly eight quadrillion years.