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Isotopes of barium

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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)

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

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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:
  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. ^ a b c d e f g Fission product

References

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  1. ^ a b c d e 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.