Isotopes of barium (₅₆Ba)

Main isotopes^[1]			Decay
	abundance	half-life (t_1/2)	mode	product
¹³⁰Ba	0.11%	(0.5–2.7)×10²¹ y	εε	¹³⁰Xe
¹³²Ba	0.1%	stable
¹³³Ba	synth	10.51 y	ε	¹³³Cs
¹³⁴Ba	2.42%	stable
¹³⁵Ba	6.59%	stable
¹³⁶Ba	7.85%	stable
¹³⁷Ba	11.2%	stable
¹³⁸Ba	71.7%	stable

Standard atomic weight A_r°(Ba)

137.327±0.007^[2]
137.33±0.01 (abridged)^[3]

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	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^{[n 7]}^{[n 8]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy			Half-life	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^{[n 7]}^{[n 8]}	Normal proportion	Range of variation
¹¹⁴Ba	56	58	113.95072(11)	530(230) ms [0.43(+30−15) s]	β⁺, p (99.59%)	¹¹³Xe	0+
					α (.37%)	¹¹⁰Xe
					β⁺ (.04%)	¹¹⁴Cs
					CD (<.0034%)^{[n 9]}	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	¹¹⁴Xe	(5/2+)#
¹¹⁶Ba	56	60	115.94162(22)#	1.3(2) s	β⁺	¹¹⁶Cs	0+
¹¹⁶Ba	56	60	115.94162(22)#	1.3(2) s	β⁺, p	¹¹⁵Xe	0+
¹¹⁷Ba	56	61	116.93832(27)	1.75(7) s	β⁺	¹¹⁷Cs	(3/2)(+#)
					β⁺, α	¹¹³I
					β⁺, p	¹¹⁶Xe
¹¹⁸Ba	56	62	117.93323(22)#	5.2(2) s	β⁺	¹¹⁸Cs	0+
¹¹⁸Ba	56	62	117.93323(22)#	5.2(2) s	β⁺, p	¹¹⁷Xe	0+
¹¹⁹Ba	56	63	118.93066(21)	5.4(3) s	β⁺	¹¹⁹Cs	(5/2+)
¹¹⁹Ba	56	63	118.93066(21)	5.4(3) s	β⁺, p	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 (.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(+)
¹²⁴Ba	56	68	123.915094(13)	11.0(5) min	β⁺	¹²⁴Cs	0+
¹²⁵Ba	56	69	124.914472(12)	3.5(4) min	β⁺	¹²⁵Cs	1/2(+#)
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	80.33(12) keV			1.9(2) s	IT	¹²⁷Ba	7/2−
¹²⁸Ba	56	72	127.9083524(17)	2.43(5) d	β⁺	¹²⁸Cs	0+
¹²⁹Ba	56	73	128.908683(11)	2.23(11) h	β⁺	¹²⁹Cs	1/2+
^129mBa	8.42(6) keV			2.16(2) h	β⁺	¹²⁹Cs	7/2+#
^129mBa	8.42(6) keV			2.16(2) h	IT	¹²⁹Ba	7/2+#
¹³⁰Ba^{[n 10]}	56	74	129.9063260(3)	1.6(±1.1)×10²¹ y	Double EC	¹³⁰Xe	0+	0.00106(1)
^130mBa	2475.12(18) keV			9.54(14) ms	IT	¹³⁰Ba	8−
¹³¹Ba	56	75	130.9069463(4)	11.50(6) d	β⁺	¹³¹Cs	1/2+
^131mBa	187.14(12) keV			14.6(2) min	IT	¹³¹Ba	9/2−
¹³²Ba	56	76	131.9050612(11)	Observationally Stable^{[n 11]}			0+	0.00101(1)
¹³³Ba	56	77	132.9060074(11)	10.51(5) y	EC	¹³³Cs	1/2+
^133mBa	288.247(9) keV			38.9(1) h	IT (99.99%)	¹³³Ba	11/2−
^133mBa	288.247(9) keV			38.9(1) h	EC (.0096%)	¹³³Cs	11/2−
¹³⁴Ba	56	78	133.90450825(27)	Stable			0+	0.02417(18)
¹³⁵Ba	56	79	134.90568845(26)	Stable			3/2+	0.06592(12)
^135mBa	268.22(2) keV			28.7(2) h	IT	¹³⁵Ba	11/2−
¹³⁶Ba	56	80	135.90457580(26)	Stable			0+	0.07854(24)
^136mBa	2030.466(18) keV			308.4(19) ms	IT	¹³⁶Ba	7−
¹³⁷Ba	56	81	136.90582721(27)	Stable			3/2+	0.11232(24)
^137m1Ba	661.659(3) keV			2.552(1) min	IT	¹³⁷Ba	11/2−
^137m2Ba	2349.1(4) keV			0.59(10) µs			(17/2−)
¹³⁸Ba^{[n 12]}	56	82	137.90524706(27)	Stable			0+	0.71698(42)
^138mBa	2090.54(6) keV			800(100) ns			6+
¹³⁹Ba^{[n 12]}	56	83	138.90884116(27)	83.06(28) min	β⁻	¹³⁹La	7/2−
¹⁴⁰Ba^{[n 12]}	56	84	139.910608(8)	12.752(3) d	β⁻	¹⁴⁰La	0+
¹⁴¹Ba^{[n 12]}	56	85	140.914404(6)	18.27(7) min	β⁻	¹⁴¹La	3/2−
¹⁴²Ba^{[n 12]}	56	86	141.916433(6)	10.6(2) min	β⁻	¹⁴²La	0+
¹⁴³Ba^{[n 12]}	56	87	142.920625(7)	14.5(3) s	β⁻	¹⁴³La	5/2−
¹⁴⁴Ba^{[n 12]}	56	88	143.922955(8)	11.5(2) s	β⁻	¹⁴⁴La	0+
¹⁴⁵Ba	56	89	144.927518(9)	4.31(16) s	β⁻	¹⁴⁵La	5/2−
¹⁴⁶Ba	56	90	145.9303632(19)	2.22(7) s	β⁻ (99.98%)	¹⁴⁶La	0+
¹⁴⁶Ba	56	90	145.9303632(19)	2.22(7) s	β⁻, n (.02%)	¹⁴⁵La	0+
¹⁴⁷Ba	56	91	146.935304(21)	0.893(1) s	β⁻ (99.94%)	¹⁴⁷La	(3/2+)
¹⁴⁷Ba	56	91	146.935304(21)	0.893(1) s	β⁻, n (.06%)	¹⁴⁶La	(3/2+)
¹⁴⁸Ba	56	92	147.9382230(16)	0.612(17) s	β⁻ (99.6%)	¹⁴⁸La	0+
¹⁴⁸Ba	56	92	147.9382230(16)	0.612(17) s	β⁻, n (.4%)	¹⁴⁷La	0+
¹⁴⁹Ba	56	93	148.9432840(27)	344(7) ms	β⁻ (99.57%)	¹⁴⁹La	3/2−#
¹⁴⁹Ba	56	93	148.9432840(27)	344(7) ms	β⁻, n (.43%)	¹⁴⁸La	3/2−#
¹⁵⁰Ba	56	94	149.946441(6)	300 ms	β⁻	¹⁵⁰La	0+
¹⁵⁰Ba	56	94	149.946441(6)	300 ms	β⁻, n (rare)	¹⁴⁹La	0+
¹⁵¹Ba	56	95	150.95176(43)#	200# ms [>300 ns]	β⁻	¹⁵¹La	3/2−#
¹⁵²Ba	56	96	151.95533(43)#	100# ms	β⁻	¹⁵²La	0+
¹⁵³Ba	56	97	152.96085(43)#	80# ms	β⁻	¹⁵³La	5/2−#
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).
^ Cluster decay is predicted but had never been observed.
^ Primordial radioisotope
^ Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 300×10¹⁸ years
^ ^a ^b ^c ^d ^e ^f ^g Fission product

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.
^ "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.

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