Isotopes of barium

Isotopes of barium (₅₆Ba)
Standard atomic weight Ar°(Ba)
	137.327±0.007; 137.33±0.01 (abridged);
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Last updated October 05, 2024

Naturally occurring barium (₅₆Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks) in 2001.^[4] This nuclide decays by double electron capture (absorbing two electrons and emitting two neutrinos), with a half-life of (0.5–2.7)×10²¹ years (about 10¹¹ times the age of the universe).

There are a total of thirty-three known radioisotopes in addition to ¹³⁰Ba. The longest-lived of these is ¹³³Ba, which has a half-life of 10.51 years. All other radioisotopes have half-lives shorter than two weeks. The longest-lived isomer is ^133mBa, which has a half-life of 38.9 hours. The shorter-lived ^137mBa (half-life 2.55 minutes) arises as the decay product of the common fission product caesium-137.

Barium-114 is predicted to undergo cluster decay, emitting a nucleus of stable ¹²C to produce ¹⁰²Sn. However this decay is not yet observed; the upper limit on the branching ratio of such decay is 0.0034%.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[5] ^{[n 2]}^{[n 3]}	Half-life ^[1]	Decay mode ^[1] ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^[1] ^{[n 7]}^{[n 8]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy			Half-life ^[1]	Decay mode ^[1] ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^[1] ^{[n 7]}^{[n 8]}	Normal proportion^[1]	Range of variation
¹¹⁴Ba	56	58	113.95072(11)	460(125) ms	β⁺ (79%)	¹¹⁴Cs	0+
					α (0.9%)	¹¹⁰Xe
					β⁺, p (20%)	¹¹³Xe
					CD (<.0034%)	¹⁰²Sn, ¹²C
¹¹⁵Ba	56	59	114.94748(22)#	0.45(5) s	β⁺	¹¹⁵Cs	5/2+#
¹¹⁵Ba	56	59	114.94748(22)#	0.45(5) s	β⁺, p (>15%)	¹¹⁴Xe	5/2+#
¹¹⁶Ba	56	60	115.94162(22)#	1.3(2) s	β⁺ (97%)	¹¹⁶Cs	0+
¹¹⁶Ba	56	60	115.94162(22)#	1.3(2) s	β⁺, p (3%)	¹¹⁵Xe	0+
¹¹⁷Ba	56	61	116.93832(27)	1.75(7) s	β⁺ (87%)	¹¹⁷Cs	(3/2+)
					β⁺, p (13%)	¹¹⁶Xe
					β⁺, α (0.024%)	¹¹³I
¹¹⁸Ba	56	62	117.93323(22)#	5.2(2) s	β⁺	¹¹⁸Cs	0+
¹¹⁹Ba	56	63	118.93066(21)	5.4(3) s	β⁺ (75%)	¹¹⁹Cs	(5/2+)
¹¹⁹Ba	56	63	118.93066(21)	5.4(3) s	β⁺, p (25%)	¹¹⁸Xe	(5/2+)
¹²⁰Ba	56	64	119.92604(32)	24(2) s	β⁺	¹²⁰Cs	0+
¹²¹Ba	56	65	120.92405(15)	29.7(15) s	β⁺ (99.98%)	¹²¹Cs	5/2+
¹²¹Ba	56	65	120.92405(15)	29.7(15) s	β⁺, p (0.02%)	¹²⁰Xe	5/2+
¹²²Ba	56	66	121.91990(3)	1.95(15) min	β⁺	¹²²Cs	0+
¹²³Ba	56	67	122.918781(13)	2.7(4) min	β⁺	¹²³Cs	5/2+
^123mBa	120.95(8) keV			830(60) ns	IT	¹²³Ba	1/2+#
¹²⁴Ba	56	68	123.915094(13)	11.0(5) min	β⁺	¹²⁴Cs	0+
¹²⁵Ba	56	69	124.914472(12)	3.3(3) min	β⁺	¹²⁵Cs	1/2+
^125mBa	120(20)# keV			2.76(14) μs	IT	¹²⁵Ba	(7/2−)
¹²⁶Ba	56	70	125.911250(13)	100(2) min	β⁺	¹²⁶Cs	0+
¹²⁷Ba	56	71	126.911091(12)	12.7(4) min	β⁺	¹²⁷Cs	1/2+
^127mBa	80.32(11) keV			1.93(7) s	IT	¹²⁷Ba	7/2−
¹²⁸Ba	56	72	127.9083524(17)	2.43(5) d	EC	¹²⁸Cs	0+
¹²⁹Ba	56	73	128.908683(11)	2.23(11) h	β⁺	¹²⁹Cs	1/2+
^129mBa	8.42(6) keV			2.135(10) h	β⁺	¹²⁹Cs	7/2+
^129mBa	8.42(6) keV			2.135(10) h	IT	¹²⁹Ba	7/2+
¹³⁰Ba^{[n 9]}	56	74	129.9063260(3)	≈ 1×10²¹ y	2EC?	¹³⁰Xe	0+	0.0011(1)
^130mBa	2475.12(18) keV			9.54(14) ms	IT	¹³⁰Ba	8−
¹³¹Ba	56	75	130.9069463(4)	11.52(1) d	β⁺	¹³¹Cs	1/2+
^131mBa	187.995(9) keV			14.26(9) min	IT	¹³¹Ba	9/2−
¹³²Ba	56	76	131.9050612(11)	Observationally Stable ^{[n 10]}			0+	0.0010(1)
¹³³Ba	56	77	132.9060074(11)	10.5379(16) y	EC	¹³³Cs	1/2+
^133mBa	288.252(9) keV			38.90(6) h	IT (99.99%)	¹³³Ba	11/2−
^133mBa	288.252(9) keV			38.90(6) h	EC (0.0104%)	¹³³Cs	11/2−
¹³⁴Ba	56	78	133.90450825(27)	Stable			0+	0.0242(15)
^134mBa	2957.2(5) keV			2.61(13) μs	IT	¹³⁴Ba	10+
¹³⁵Ba	56	79	134.90568845(26)	Stable			3/2+	0.0659(10)
^135m1Ba	268.218(20) keV			28.11(2) h	IT	¹³⁵Ba	11/2−
^135m2Ba	2388.0(5) keV			1.06(4) ms	IT	¹³⁵Ba	(23/2+)
¹³⁶Ba	56	80	135.90457580(26)	Stable			0+	0.0785(24)
^136m1Ba	2030.535(18) keV			308.4(19) ms	IT	¹³⁶Ba	7−
^136m2Ba	3357.19(25) keV			91(2) ns	IT	¹³⁶Ba	10+
¹³⁷Ba	56	81	136.90582721(27)	Stable			3/2+	0.1123(23)
^137m1Ba	661.659(3) keV			2.552(1) min	IT	¹³⁷Ba	11/2−
^137m2Ba	2349.1(5) keV			589(20) ns	IT	¹³⁷Ba	(19/2−)
¹³⁸Ba^{[n 11]}	56	82	137.90524706(27)	Stable			0+	0.7170(29)
^138mBa	2090.536(21) keV			850(100) ns	IT	¹³⁸Ba	6+
¹³⁹Ba^{[n 11]}	56	83	138.90884116(27)	82.93(9) min	β⁻	¹³⁹La	7/2−
¹⁴⁰Ba^{[n 11]}	56	84	139.910608(8)	12.7534(21) d	β⁻	¹⁴⁰La	0+
¹⁴¹Ba^{[n 11]}	56	85	140.914404(6)	18.27(7) min	β⁻	¹⁴¹La	3/2−
¹⁴²Ba^{[n 11]}	56	86	141.916433(6)	10.6(2) min	β⁻	¹⁴²La	0+
¹⁴³Ba^{[n 11]}	56	87	142.920625(7)	14.5(3) s	β⁻	¹⁴³La	5/2−
¹⁴⁴Ba^{[n 11]}	56	88	143.922955(8)	11.73(8) s	β⁻	¹⁴⁴La	0+
¹⁴⁵Ba	56	89	144.927518(9)	4.31(16) s	β⁻	¹⁴⁵La	5/2−
¹⁴⁶Ba	56	90	145.9303632(19)	2.15(4) s	β⁻	¹⁴⁶La	0+
¹⁴⁷Ba	56	91	146.935304(21)	893(1) ms	β⁻ (99.93%)	¹⁴⁷La	5/2−
¹⁴⁷Ba	56	91	146.935304(21)	893(1) ms	β⁻, n (0.07%)	¹⁴⁶La	5/2−
¹⁴⁸Ba	56	92	147.9382230(16)	620(5) ms	β⁻ (99.6%)	¹⁴⁸La	0+
¹⁴⁸Ba	56	92	147.9382230(16)	620(5) ms	β⁻, n (0.4%)	¹⁴⁷La	0+
¹⁴⁹Ba	56	93	148.9432840(27)	349(4) ms	β⁻ (96.1%)	¹⁴⁹La	3/2−#
¹⁴⁹Ba	56	93	148.9432840(27)	349(4) ms	β⁻, n (3.9%)	¹⁴⁸La	3/2−#
¹⁵⁰Ba	56	94	149.946441(6)	258(5) ms	β⁻ (99.0%)	¹⁵⁰La	0+
¹⁵⁰Ba	56	94	149.946441(6)	258(5) ms	β⁻, n (1.0%)	¹⁴⁹La	0+
¹⁵¹Ba	56	95	150.95176(43)#	167(5) ms	β⁻	¹⁵¹La	3/2−#
¹⁵¹Ba	56	95	150.95176(43)#	167(5) ms	β⁻, n?	¹⁵⁰La	3/2−#
¹⁵²Ba	56	96	151.95533(43)#	139(8) ms	β⁻	¹⁵²La	0+
¹⁵²Ba	56	96	151.95533(43)#	139(8) ms	β⁻, n?	¹⁵¹La	0+
¹⁵³Ba	56	97	152.96085(43)#	113(39) ms	β⁻	¹⁵³La	5/2−#
					β⁻, n?	¹⁵²La
					β⁻, 2n?	¹⁵¹La
¹⁵⁴Ba	56	98	153.96466(54)#	53(48) ms	β⁻	¹⁵⁴La	0+
This table header & footer: view

↑ ^mBa – 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
n: Neutron emission
p: Proton emission
↑ Bold italics symbol as daughter – Daughter product is nearly stable.
↑ Bold symbol as daughter – Daughter product is stable.
↑ ( ) 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).
↑ Primordial radioisotope
↑ Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 3×10²⁰ years
1 2 3 4 5 6 7 Fission product

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References

1 2 3 4 5 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.
↑ "Standard Atomic Weights: Barium". CIAAW. 1985.
↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
↑ Meshik, A.P.; Hohenberg, C.M.; Pravdivtseva, O.V.; Kapusta, Y.S. (2001). "Weak decay of ¹³⁰Ba and ¹³²Ba: Geochemical measurements". Physical Review C. 64 (3): 035205–1–035205–6. Bibcode:2001PhRvC..64c5205M. doi:10.1103/PhysRevC.64.035205.
↑ 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.

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.
Half-life of ¹³⁰Ba from:
- A. P. Meshik; C. M. Hohenberg; O. V. Pravdivtseva; Ya. S. Kapusta (2001). "Weak decay of ¹³⁰Ba and ¹³²Ba: Geochemical measurements". Physical Review C . 64 (3): 035205 [6 pages]. Bibcode:2001PhRvC..64c5205M. doi:10.1103/PhysRevC.64.035205.
- M. Pujol; B. Marty; P. Burnard; P. Philippot (2009). "Xenon in Archean barite: Weak decay of ¹³⁰Ba, mass-dependent isotopic fractionation and implication for barite formation". Geochimica et Cosmochimica Acta . 73 (22): 6834–6846. Bibcode:2009GeCoA..73.6834P. doi:10.1016/j.gca.2009.08.002.

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[5] Ba – Excited nuclear isomer.

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

[TMS-8] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[9] Modes of decay:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
n: Neutron emission
p: Proton emission

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

[11] Bold symbol as daughter – Daughter product is stable.

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

[TNN-13] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[14] Primordial radioisotope

[15] Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 3×10²⁰ years

[FP-16] 1 2 3 4 5 6 7 Fission product

[NUBASE2020-1] 1 2 3 4 5 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.

[2] "Standard Atomic Weights: Barium". CIAAW. 1985.

[CIAAW2021-3] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[Ba130-4] Meshik, A.P.; Hohenberg, C.M.; Pravdivtseva, O.V.; Kapusta, Y.S. (2001). "Weak decay of ¹³⁰Ba and ¹³²Ba: Geochemical measurements". Physical Review C. 64 (3): 035205–1–035205–6. Bibcode:2001PhRvC..64c5205M. doi:10.1103/PhysRevC.64.035205.

[AME2020_II-6] 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.

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[2]

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[4]

[n 1]

[5]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[n 7]

[n 8]

[n 9]

[n 10]

[n 11]

CD:	Cluster decay
EC:	Electron capture
IT:	Isomeric transition
n:	Neutron emission
p:	Proton emission