Isotopes of barium

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