La139
La-139, or 139La, is the only stable isotope of the chemical element lanthanum (atomic number 57). In nature, nearly all lanthanum is found as 139La, making it the dominant isotope in natural samples. A second isotope, 138La, exists only at trace levels and is radioactive, with a very long half-life on cosmological timescales, so it is present only as a minor component of naturally occurring lanthanum.
Nuclear properties of 139La include a nuclear spin of 7/2 and a quadrupolar nature, which influences how
Occurrence and production: Lanthanum is a rare earth element mined from minerals such as monazite and bastnäsite.
Applications and significance: The high natural abundance and favorable nuclear properties of 139La make it a