Isotopes of barium

Template:Infobox barium isotopes 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,[1][2] presumably decaying by double electron capture with a half-life of (0.5–2.7)×1021 years (about 1011 times the age of the universe). The two measurements are discordant; the above reflects the total range, the value in the table below is a crude average.

With the total range of mass numbers known 114 to 154, there are thirty-three known radioisotopes in addition to 130Ba. The longest-lived of these is 133Ba, which has a half-life of 10.538 years; all others have half-lives shorter than two weeks. The longest-lived isomers are 133mBa at 38.90 hours and 135m1Ba at 28.11 hours. The analogous 137m1Ba (half-life 2.552 minutes) occurs in the decay of the common fission product caesium-137.

Barium-114 is theorized to undergo cluster decay, emitting a nucleus of stable 12C to produce 102Sn. This decay has not been observed, with only an upper limit on the branching ratio of such decay (0.0034%).

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
| Decay
mode
[n 4] | Daughter
isotope
[n 5][n 6] | Spin and
parity
[n 7][n 8] | Physics:Natural abundance (mole fraction)

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Excitation energy  | Normal proportion  | 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  | (3/2+)[3] |  |
β+, p (25%)  | 118Xe
119mBa[3] | 66.0 keV  | 360(20) ns  | IT  | 119Ba  | (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+  |  |
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 | εε  | 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[n 11] | 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[n 11] | 56  | 81  | 136.90582721(27)  | Stable | 3/2+  | 0.1123(23)  |
137m1Ba[n 11] | 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  | 56  | 85  | 140.914404(6)  | 18.27(7) min  | β− | 141La  | 3/2−  |  |
142Ba  | 56  | 86  | 141.916433(6)  | 10.6(2) min  | β− | 142La  | 0+  |  |
143Ba  | 56  | 87  | 142.920625(7)  | 14.5(3) s  | β− | 143La  | 5/2−  |  |
144Ba  | 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+  |  |
155Ba[4] | 56  | 99  |  |  |  |  |  |  |

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 radionuclide
10. ↑ Believed to undergo β+β+ decay to 132Xe with a half-life over 3×1020 years
11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 Fission product

## See also

Daughter products other than barium

* Isotopes of lanthanum
* Isotopes of caesium
* Isotopes of xenon
* Isotopes of iodine
* Isotopes of tin
* Isotopes of carbon

## References

1. ↑ 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. doi:10.1103/PhysRevC.64.035205. Bibcode: 2001PhRvC..64c5205M. https://zenodo.org/record/1063702.
2. ↑ 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. doi:10.1016/j.gca.2009.08.002. Bibcode: 2009GeCoA..73.6834P.
3. ↑ 3.0 3.1 Zheng, K. K.; Petrache, C. M.; Zhang, Z. H.; Astier, A.; Lv, B. F.; Greenlees, P. T.; Grahn, T.; Julin, R. et al. (30 July 2021). "Neutron excitations in Ba 119". Physical Review C 104 (1). doi:10.1103/PhysRevC.104.014326. https://jyx.jyu.fi/bitstream/123456789/77280/2/PhysRevC.104.014326.pdf.
4. ↑ Sumikama, Toshiyuki; Fukuda, Naoki; Kubo, Toshiyuki; Suzuki, Hiroshi; Takeda, Hiroyuki; Inabe, Naohito; Kameda, Daisuke; Ahn, Deuk Soon et al. (15 February 2026). "Expanding the Isotopic Frontier: Seven New Neutron-Rich Rare-Earth Isotopes Observed at RIKEN RI Beam Factory". Journal of the Physical Society of Japan 95 (2). doi:10.7566/JPSJ.95.024202.

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