Isotopes of barium

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).

Isotopes of barium (₅₆Ba)

Main isotopes^[1] Decay abun­dance half-life (t1/2) mode pro­duct ^130Ba 0.11% (0.5–2.7)×10^21 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 Ar°(Ba)
	137.327±0.007^[2] 137.33±0.01 (abridged)^[3]
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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)
	Excitation energy							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+)#
					β^+, p	^114Xe
^116Ba	56	60	115.94162(22)#	1.3(2) s	β^+	^116Cs	0+
					β^+, p	^115Xe
^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+
					β^+, p	^117Xe
^119Ba	56	63	118.93066(21)	5.4(3) s	β^+	^119Cs	(5/2+)
					β^+, p	^118Xe
^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(+)
					β^+, p (.02%)	^120Xe
^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+#
					IT	^129Ba
^130Ba^[n 10]	56	74	129.9063260(3)	1.6(±1.1)×10^21 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−
					EC (.0096%)	^133Cs
^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+
					β^−, n (.02%)	^145La
^147Ba	56	91	146.935304(21)	0.893(1) s	β^− (99.94%)	^147La	(3/2+)
					β^−, n (.06%)	^146La
^148Ba	56	92	147.9382230(16)	0.612(17) s	β^− (99.6%)	^148La	0+
					β^−, n (.4%)	^147La
^149Ba	56	93	148.9432840(27)	344(7) ms	β^− (99.57%)	^149La	3/2−#
					β^−, n (.43%)	^148La
^150Ba	56	94	149.946441(6)	300 ms	β^−	^150La	0+
					β^−, n (rare)	^149La
^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

1. ^mBa – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Modes of decay:

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

5. Bold italics symbol as daughter – Daughter product is nearly stable.
6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
9. Cluster decay is predicted but had never been observed.
10. Primordial radioisotope
11. Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 300×10¹⁸ years
12. Fission product

References

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.
2. "Standard Atomic Weights: Barium". CIAAW. 1985.
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.
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.
5. 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.