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)×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 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[1]	Decay mode[1] [n 4]	Daughter isotope [n 5][n 6]	Spin and parity[1] [n 7][n 8]	Natural abundance (mole fraction)
	Excitation energy							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+#
					β+, p (>15%)	114Xe
116Ba	56	60	115.94162(22)#	1.3(2) s	β+ (97%)	116Cs	0+
					β+, p (3%)	115Xe
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+)
					β+, p (25%)	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 (0.02%)	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+
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+
					IT	129Ba
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−
					EC (0.0104%)	133Cs
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−
					β−, n (0.07%)	146La
148Ba	56	92	147.9382230(16)	620(5) ms	β− (99.6%)	148La	0+
					β−, n (0.4%)	147La
149Ba	56	93	148.9432840(27)	349(4) ms	β− (96.1%)	149La	3/2−#
					β−, n (3.9%)	148La
150Ba	56	94	149.946441(6)	258(5) ms	β− (99.0%)	150La	0+
					β−, n (1.0%)	149La
151Ba	56	95	150.95176(43)#	167(5) ms	β−	151La	3/2−#
					β−, n?	150La
152Ba	56	96	151.95533(43)#	139(8) ms	β−	152La	0+
					β−, n?	151La
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

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. Primordial radioisotope
10. Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 3×10²⁰ years
11. 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.