Isotopes of barium

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%.

Relative atomic mass: 137.327(7).

Table

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)×10^21 y	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) y	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[n 8]	56	85	140.914411(9)	18.27(7) min	β^−	^141La	3/2−
^142Ba[n 8]	56	86	141.916453(7)	10.6(2) min	β^−	^142La	0+
^143Ba[n 8]	56	87	142.920627(14)	14.5(3) s	β^−	^143La	5/2−
^144Ba[n 8]	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. Theoretically capable of spontaneous fission
8. Fission product

Notes

• 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

References

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. 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.