Isotopes of barium

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Naturally occurring barium (Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, recently identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks). 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, but most of these are highly radioactive with half-lives in the several millisecond to several minute range. The only notable exceptions are 133Ba which has a half-life of 10.51 years, 131Ba (11.5 days), and 137mBa (2.55 minutes), which is the decay product of 137Cs (30.17 years, and a common fission product).

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%.

Standard atomic mass: 137.327(7) u

Table[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life[n 1] decay
mode(s)[1][n 2]
daughter
isotope(s)[n 3]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
114Ba 56 58 113.95068(15) 530(230) ms
[0.43(+30−15) s]
β+, p (99.59%) 113Xe 0+
α (.37%) 110Xe
β+ (.04%) 114Cs
CD (<.0034%)[n 4] 102Sn, 12C
115Ba 56 59 114.94737(64)# 0.45(5) s β+ 115Cs (5/2+)#
β+, p 114Xe
116Ba 56 60 115.94138(43)# 1.3(2) s β+ 116Cs 0+
β+, p 115Xe
117Ba 56 61 116.93850(32)# 1.75(7) s β+ 117Cs (3/2)(+#)
β+, α 113I
β+, p 116Xe
118Ba 56 62 117.93304(21)# 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 69 124.914473(12) 3.5(4) min β+ 125Cs 1/2(+#)
126Ba 56 70 125.911250(13) 100(2) min β+ 126Cs 0+
127Ba 56 71 126.911094(12) 12.7(4) min β+ 127Cs 1/2+
127mBa 80.33(12) keV 1.9(2) s IT 127Ba 7/2−
128Ba 56 72 127.908318(11) 2.43(5) d β+ 128Cs 0+
129Ba 56 73 128.908679(12) 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 5] 56 74 129.9063208(30) 1.6(±1.1)×1021 yrs Double EC 130Xe 0+ 0.00106(1)
130mBa 2475.12(18) keV 9.54(14) ms IT 130Ba 8−
131Ba 56 75 130.906941(3) 11.50(6) d β+ 131Cs 1/2+
131mBa 187.14(12) keV 14.6(2) min IT 131Ba 9/2−
132Ba 56 76 131.9050613(11) Observationally Stable[n 6] 0+ 0.00101(1)
133Ba 56 77 132.9060075(11) 10.51(5) yrs EC 133Cs 1/2+
133mBa 288.247(9) keV 38.9(1) h IT (99.99%) 133Ba 11/2−
EC (.0096%) 133Cs
134Ba 56 78 133.9045084(4) Stable[n 7] 0+ 0.02417(18)
135Ba 56 79 134.9056886(4) Stable[n 7] 3/2+ 0.06592(12)
135mBa 268.22(2) keV 28.7(2) h IT 135Ba 11/2−
136Ba 56 80 135.9045759(4) Stable[n 7] 0+ 0.07854(24)
136mBa 2030.466(18) keV 308.4(19) ms IT 136Ba 7−
137Ba 56 81 136.9058274(5) Stable[n 7] 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 8] 56 82 137.9052472(5) Stable[n 7] 0+ 0.71698(42)
138mBa 2090.54(6) keV 800(100) ns 6+
139Ba[n 8] 56 83 138.9088413(5) 83.06(28) min β- 139La 7/2−
140Ba[n 8] 56 84 139.910605(9) 12.752(3) d β- 140La 0+
141Ba 56 85 140.914411(9) 18.27(7) min β- 141La 3/2−
142Ba 56 86 141.916453(7) 10.6(2) min β- 142La 0+
143Ba 56 87 142.920627(14) 14.5(3) s β- 143La 5/2−
144Ba 56 88 143.922953(14) 11.5(2) s β- 144La 0+
145Ba 56 89 144.92763(8) 4.31(16) s β- 145La 5/2−
146Ba 56 90 145.93022(8) 2.22(7) s β- (99.98%) 146La 0+
β-, n (.02%) 145La
147Ba 56 91 146.93495(22)# 0.893(1) s β- (99.94%) 147La (3/2+)
β-, n (.06%) 146La
148Ba 56 92 147.93772(9) 0.612(17) s β- (99.6%) 148La 0+
β-, n (.4%) 147La
149Ba 56 93 148.94258(21)# 344(7) ms β- (99.57%) 149La 3/2−#
β-, n (.43%) 148La
150Ba 56 94 149.94568(43)# 300 ms β- 150La 0+
β-, n (rare) 149La
151Ba 56 95 150.95081(43)# 200# ms [>300 ns] β- 151La 3/2−#
152Ba 56 96 151.95427(54)# 100# ms β- 152La 0+
153Ba 56 97 152.95961(86)# 80# ms β- 153La 5/2−#
  1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
  2. ^ Abbreviations:
    CD: Cluster decay
    EC: Electron capture
    IT: Isomeric transition
  3. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
  4. ^ Cluster decay is predicted but had never been observed.
  5. ^ Primordial radioisotope
  6. ^ Believed to undergo β+β+ decay to 132Xe with a half-life over 300×1018 years
  7. ^ a b c d e Theoretically capable of spontaneous fission
  8. ^ a b c Fission product

Notes[edit]

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

See also[edit]


References[edit]

  1. ^ http://www.nucleonica.net/unc.aspx


Isotopes of caesium Isotopes of barium Isotopes of lanthanum
Table of nuclides