T or 13H. at. wt 3.016. Exists in the diatomic state, T2; mol wt 6.032. Naturally occurring radioactive isotope of hydrogen, q.v., (T 12.32 yr, low energy β emitter). Under normal conditions the total atmospheric content of molecular T2 gas is only 11 g. First prepd by the bombardment of deuterophosphoric acid with fast deuterons: M. L. E. Oliphant et al., Proc. Roy. Soc. A144, 692 (1934); T. W. Bonner, Phys. Rev. 53, 711 (1938). Produced commercially from 6Li by slow neutron bombardment: 36Li + 01n → 13H + 24He. Prepn by neutron irradiation of lithium fluoride: Jenks et al., US 3079317 (1963). Reviews: E. A. Evans, Tritium and Its Compounds (Butterworth, London, 1966) 441 pp; Mackay, Dove, “Deuterium and Tritium” in Comprehensive Inorganic Chemistry vol. 1, J. C. Bailar Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 77-116; Chemistry of the Elements N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 38-74; J. J. Katz in Kirk-Othmer Encyclopedia of Chemical Technology vol. 8 (Wiley-Interscience, New York, 4th ed., 1993) pp 17-30.