Tritium

Tritium  occurs in the upper atmosphere and is formed naturally by reaction 1.1, involving neutrons arriving from outer space. Tritium (see Section 2.8) was first obtained synthetically by the bombardment of deuterium compounds such as [ND₄]₂SO₄ with fast neutrons, but is now prepared from lithium deuteride, LiF or Mg/Li enriched in ⁶₃ Li (equation 1.2).

       (1.1)

          (1.2)

Tritium is radioactive, a weak b-emitter with t_1/2= 12.3 yr.   It is used extensively as a tracer, in both chemical and biochemical studies; its weak radioactivity, rapid excretion and failure to concentrate in vulnerable organs make it one of the least toxic radioisotopes.