Isotopes of barium explained

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] 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

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

References

Isotope masses from:
- - Isotopic compositions and standard atomic masses from:
    - - Half-life, spin, and isomer data selected from the following sources.
        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 . . 64 . 3 . 035205 [6 pages] . 10.1103/PhysRevC.64.035205. 2001PhRvC..64c5205M .
- 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 . . 73. 22 . 6834–6846 . 10.1016/j.gca.2009.08.002. 2009GeCoA..73.6834P .

Notes and References

Meshik . A.P. . Hohenberg . C.M. . Pravdivtseva . O.V. . Kapusta . Y.S. . Weak decay of ¹³⁰Ba and ¹³²Ba: Geochemical measurements . 2001 . Physical Review C . 64 . 3 . 035205–1–035205–6 . 10.1103/PhysRevC.64.035205. 2001PhRvC..64c5205M .
Primordial radioisotope
Believed to undergo β⁺β⁺ decay to ¹³²Xe with a half-life over 3×10²⁰ years
[Fission product]
[Fission product]
[Fission product]
[Fission product]
[Fission product]