Physics:Isotopes of actinium

Short description: Nuclides with atomic number of 89 but with different mass numbers

Actinium (₈₉Ac) has no stable isotopes and no characteristic terrestrial isotopic composition, thus a standard atomic weight cannot be given. There are 33 known isotopes, from ²⁰⁴Ac to ²³⁶Ac, and 7 isomers. Three isotopes are found in nature, ²²⁵Ac, ²²⁷Ac and ²²⁸Ac, as intermediate decay products of, respectively, ²³⁷Np, ²³⁵U, and ²³²Th. ²²⁸Ac and ²²⁵Ac are extremely rare, so almost all natural actinium is ²²⁷Ac.

The most stable isotopes are ²²⁷Ac with a half-life of 21.772 years, ²²⁵Ac with a half-life of 10.0 days, and ²²⁶Ac with a half-life of 29.37 hours. All other isotopes have half-lives under 10 hours, and most under a minute. The shortest-lived known isotope is ²¹⁷Ac with a half-life of 69 ns.

Purified ²²⁷Ac comes into equilibrium with its decay products (²²⁷Th and ²²³Fr) after 185 days.^[1]

List of isotopes

Nuclide ^{[n 1]}	Historic name	Z	N	Isotopic mass (u) ^{[n 2]}^{[n 3]}	Half-life	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}	Spin and parity ^{[n 6]}^{[n 7]}	Isotopic abundance
Nuclide ^{[n 1]}	Historic name	Excitation energy^{[n 7]}			Half-life	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}	Spin and parity ^{[n 6]}^{[n 7]}	Isotopic abundance
²⁰⁴Ac^[2]		89	115		7.4+2.2 −1.4 ms	α	²⁰⁰Fr
²⁰⁵Ac^[3]		89	116		7.7+2.7 −1.6 ms^[2]	α	²⁰¹Fr	9/2−?
²⁰⁶Ac		89	117	206.01450(8)	25(7) ms	α	²⁰²Fr	(3+)
^206m1Ac		80(50) keV			15(6) ms	α	²⁰²Fr
^206m2Ac		290(110)# keV			41(16) ms	α	^202mFr	(10−)
²⁰⁷Ac		89	118	207.01195(6)	31(8) ms [27(+11−6) ms]	α	²⁰³Fr	9/2−#
²⁰⁸Ac		89	119	208.01155(6)	97(16) ms [95(+24−16) ms]	α (99%)	²⁰⁴Fr	(3+)
²⁰⁸Ac		89	119	208.01155(6)	97(16) ms [95(+24−16) ms]	β⁺ (1%)	²⁰⁸Ra	(3+)
^208mAc		506(26) keV			28(7) ms [25(+9−5) ms]	α (89%)	²⁰⁴Fr	(10−)
						IT (10%)	²⁰⁸Ac
						β⁺ (1%)	²⁰⁸Ra
²⁰⁹Ac		89	120	209.00949(5)	92(11) ms	α (99%)	²⁰⁵Fr	(9/2−)
²⁰⁹Ac		89	120	209.00949(5)	92(11) ms	β⁺ (1%)	²⁰⁹Ra	(9/2−)
²¹⁰Ac		89	121	210.00944(6)	350(40) ms	α (96%)	²⁰⁶Fr	7+#
²¹⁰Ac		89	121	210.00944(6)	350(40) ms	β⁺ (4%)	²¹⁰Ra	7+#
²¹¹Ac		89	122	211.00773(8)	213(25) ms	α (99.8%)	²⁰⁷Fr	9/2−#
²¹¹Ac		89	122	211.00773(8)	213(25) ms	β⁺ (.2%)	²¹¹Ra	9/2−#
²¹²Ac		89	123	212.00781(7)	920(50) ms	α (97%)	²⁰⁸Fr	6+#
²¹²Ac		89	123	212.00781(7)	920(50) ms	β⁺ (3%)	²¹²Ra	6+#
²¹³Ac		89	124	213.00661(6)	731(17) ms	α	²⁰⁹Fr	(9/2−)#
²¹³Ac		89	124	213.00661(6)	731(17) ms	β⁺ (rare)	²¹³Ra	(9/2−)#
²¹⁴Ac		89	125	214.006902(24)	8.2(2) s	α (89%)	²¹⁰Fr	(5+)#
²¹⁴Ac		89	125	214.006902(24)	8.2(2) s	β⁺ (11%)	²¹⁴Ra	(5+)#
²¹⁵Ac		89	126	215.006454(23)	0.17(1) s	α (99.91%)	²¹¹Fr	9/2−
²¹⁵Ac		89	126	215.006454(23)	0.17(1) s	β⁺ (.09%)	²¹⁵Ra	9/2−
²¹⁶Ac		89	127	216.008720(29)	0.440(16) ms	α	²¹²Fr	(1−)
²¹⁶Ac		89	127	216.008720(29)	0.440(16) ms	β⁺ (7×10⁻⁵%)	²¹⁶Ra	(1−)
^216mAc		44(7) keV			443(7) µs			(9−)
²¹⁷Ac		89	128	217.009347(14)	69(4) ns	α	²¹³Fr	9/2−
²¹⁷Ac		89	128	217.009347(14)	69(4) ns	β⁺ (6.9×10⁻⁹%)	²¹⁷Ra	9/2−
^217mAc		2012(20) keV			740(40) ns			(29/2)+
²¹⁸Ac		89	129	218.01164(5)	1.08(9) µs	α	²¹⁴Fr	(1−)#
^218mAc		584(50)# keV			103(11) ns			(11+)
²¹⁹Ac		89	130	219.01242(5)	11.8(15) µs	α	²¹⁵Fr	9/2−
²¹⁹Ac		89	130	219.01242(5)	11.8(15) µs	β⁺ (10⁻⁶%)	²¹⁹Ra	9/2−
²²⁰Ac		89	131	220.014763(16)	26.36(19) ms	α	²¹⁶Fr	(3−)
²²⁰Ac		89	131	220.014763(16)	26.36(19) ms	β⁺ (5×10⁻⁴%)	²²⁰Ra	(3−)
²²¹Ac		89	132	221.01559(5)	52(2) ms	α	²¹⁷Fr	9/2−#
²²²Ac		89	133	222.017844(6)	5.0(5) s	α (99%)	²¹⁸Fr	1−
²²²Ac		89	133	222.017844(6)	5.0(5) s	β⁺ (1%)	²²²Ra	1−
^222mAc		200(150)# keV			1.05(7) min	α (88.6%)	²¹⁸Fr	high
						IT (10%)	²²²Ac
						β⁺ (1.4%)	²²²Ra
²²³Ac		89	134	223.019137(8)	2.10(5) min	α (99%)	²¹⁹Fr	(5/2−)
						EC (1%)	²²³Ra
						CD (3.2×10⁻⁹%)	²⁰⁹Bi ¹⁴C
²²⁴Ac		89	135	224.021723(4)	2.78(17) h	β⁺ (90.9%)	²²⁴Ra	0−
						α (9.1%)	²²⁰Fr
						β⁻ (1.6%)	²²⁴Th
²²⁵Ac^{[n 8]}		89	136	225.023230(5)	10.0(1) d	α	²²¹Fr	(3/2−)	Trace^{[n 9]}
²²⁵Ac^{[n 8]}		89	136	225.023230(5)	10.0(1) d	CD (6×10⁻¹⁰%)	²¹¹Bi ¹⁴C	(3/2−)	Trace^{[n 9]}
²²⁶Ac		89	137	226.026098(4)	29.37(12) h	β⁻ (83%)	²²⁶Th	(1)(−#)
						EC (17%)	²²⁶Ra
						α (.006%)	²²²Fr
²²⁷Ac	Actinium^{[n 10]}	89	138	227.0277521(26)	21.772(3) y	β⁻ (98.62%)	²²⁷Th	3/2−	Trace^{[n 11]}
²²⁷Ac	Actinium^{[n 10]}	89	138	227.0277521(26)	21.772(3) y	α (1.38%)	²²³Fr	3/2−	Trace^{[n 11]}
²²⁸Ac	Mesothorium 2	89	139	228.0310211(27)	6.13(2) h	β⁻	²²⁸Th	3+	Trace^{[n 12]}
²²⁹Ac		89	140	229.03302(4)	62.7(5) min	β⁻	²²⁹Th	(3/2+)
²³⁰Ac		89	141	230.03629(32)	122(3) s	β⁻	²³⁰Th	(1+)
²³¹Ac		89	142	231.03856(11)	7.5(1) min	β⁻	²³¹Th	(1/2+)
²³²Ac		89	143	232.04203(11)	119(5) s	β⁻	²³²Th	(1+)
²³³Ac		89	144	233.04455(32)#	145(10) s	β⁻	²³³Th	(1/2+)
²³⁴Ac		89	145	234.04842(43)#	44(7) s	β⁻	²³⁴Th
²³⁵Ac		89	146	235.05123(38)#	60(4) s	β⁻	²³⁵Th	1/2+#
²³⁶Ac^[4]		89	147	236.05530(54)#	72+345 −33 s	β⁻	²³⁶Th

↑ ^mAc – 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:

CD: Cluster decay

EC: Electron capture

IT: Isomeric transition
↑ Bold italics symbol as daughter – Daughter product is nearly stable.
↑ ( ) spin value – Indicates spin with weak assignment arguments.
↑ ^7.0 ^7.1 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
↑ Has medical uses
↑ Intermediate decay product of ²³⁷Np
↑ Source of element's name
↑ Intermediate decay product of ²³⁵U
↑ Intermediate decay product of ²³²Th

Actinides vs fission products

Actinides and fission products by half-life v · d · e
Actinides^[5] by decay chain				Half-life range (y)	Fission products of ²³⁵U by yield<ref>Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.</ref>
4n	4n+1	4n+2	4n+3
4n	4n+1	4n+2	4n+3			4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6	†		¹⁵⁵Eu^þ
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29		⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97		¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
²⁴⁸Bk^[6]	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351	No fission products have a half-life in the range of 100–210 k years ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[7]	430–900
		²²⁶Ra^№	²⁴⁷Bk	1.3 k – 1.6 k
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7 k – 7.4 k
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3 k – 8.5 k
			²³⁹Pu^ƒ	24.1 k
		²³⁰Th^№	²³¹Pa^№	32 k – 76 k
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150 k – 250 k	‡	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327 k – 375 k			⁷⁹Se^₡
				1.53 M		⁹³Zr
	²³⁷Np^ƒ			2.1 M – 6.5 M		¹³⁵Cs^₡	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15 M – 24 M			¹²⁹I^₡
²⁴⁴Pu				80 M	... nor beyond 15.7 M years^[8]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7 G – 14.1 G	... nor beyond 15.7 M years^[8]
Legend for superscript symbols ₡ has thermal neutron capture cross section in the range of 8–50 barns ƒ fissile m metastable isomer № primarily a naturally occurring radioactive material (NORM) þ neutron poison (thermal neutron capture cross section greater than 3k barns) † range 4–97 y: Medium-lived fission product ‡ over 200,000 y: Long-lived fission product

References

↑ G. D. Considine, ed (2005). "Chemical Elements". Van Nostrand's Encyclopedia of Chemistry. Wiley-Interscience. p. 332. ISBN 978-0-471-61525-5.
↑ ^2.0 ^2.1 Huang, M. H.; Gan, Z. G.; Zhang, Z. Y. et al. (10 November 2022). "α decay of the new isotope ²⁰⁴Ac" (in en). Physics Letters B 834: 137484. doi:10.1016/j.physletb.2022.137484. ISSN 0370-2693. Bibcode: 2022PhLB..83437484H.
↑ Zhang, Z. Y.; Gan, Z. G.; Ma, L. et al. (January 2014). "α decay of the new neutron-deficient isotope ²⁰⁵Ac". Physical Review C 89 (1): 014308. doi:10.1103/PhysRevC.89.014308. Bibcode: 2014PhRvC..89a4308Z. http://journals.aps.org/prc/abstract/10.1103/PhysRevC.89.014308.
↑ Chen, L. (2010). "Discovery and investigation of heavy neutron-rich isotopes with time-resolved Schottky spectrometry in the element range from thallium to actinium". Physics Letters B 691 (5): 234–237. doi:10.1016/j.physletb.2010.05.078. Bibcode: 2010PhLB..691..234C. http://epubs.surrey.ac.uk/7511/2/10_esr-trans-pb_plb_chen_preprint.pdf.
↑ 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.
↑ 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. doi:10.1016/0029-5582(65)90719-4. Bibcode: 1965NucPh..71..299M.
"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 y. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."
↑ 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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
Isotopic compositions and standard atomic masses from:
- 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.
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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/.
- Lide, David R., ed (2004). "11. Table of the Isotopes". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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Original source: https://en.wikipedia.org/wiki/Isotopes of actinium. Read more

[2] Ac – Excited nuclear isomer.

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

[TMS-4] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[5] Modes of decay:

CD: Cluster decay

EC: Electron capture

IT: Isomeric transition

[6] Bold italics symbol as daughter – Daughter product is nearly stable.

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

[TNN-8] 7.0 ^7.1 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[11] Has medical uses

[12] Intermediate decay product of ²³⁷Np

[13] Source of element's name

[14] Intermediate decay product of ²³⁵U

[15] Intermediate decay product of ²³²Th

[nostrand332-1] G. D. Considine, ed (2005). "Chemical Elements". Van Nostrand's Encyclopedia of Chemistry. Wiley-Interscience. p. 332. ISBN 978-0-471-61525-5.

[204Ac-9] 2.0 ^2.1 Huang, M. H.; Gan, Z. G.; Zhang, Z. Y. et al. (10 November 2022). "α decay of the new isotope ²⁰⁴Ac" (in en). Physics Letters B 834: 137484. doi:10.1016/j.physletb.2022.137484. ISSN 0370-2693. Bibcode: 2022PhLB..83437484H.

[ZhangEtAl2014-10] Zhang, Z. Y.; Gan, Z. G.; Ma, L. et al. (January 2014). "α decay of the new neutron-deficient isotope ²⁰⁵Ac". Physical Review C 89 (1): 014308. doi:10.1103/PhysRevC.89.014308. Bibcode: 2014PhRvC..89a4308Z. http://journals.aps.org/prc/abstract/10.1103/PhysRevC.89.014308.

[236Ac-Chen-16] Chen, L. (2010). "Discovery and investigation of heavy neutron-rich isotopes with time-resolved Schottky spectrometry in the element range from thallium to actinium". Physics Letters B 691 (5): 234–237. doi:10.1016/j.physletb.2010.05.078. Bibcode: 2010PhLB..691..234C. http://epubs.surrey.ac.uk/7511/2/10_esr-trans-pb_plb_chen_preprint.pdf.

[17] 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.

[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. doi:10.1016/0029-5582(65)90719-4. Bibcode: 1965NucPh..71..299M.
"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 y. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."

[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.

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