Noun
hydrogen-3 (uncountable)
Synonym for tritium (isotope of hydrogen).
Most of this comes from the decay of tritium (hydrogen-3), which decays into helium-3 with a half life of 12.3 years. Source: Internet
For hydrogen-1, hydrogen-2 ( deuterium ), and hydrogen-3 ( tritium ) the constant must be slightly modified to use the reduced mass of the system, rather than simply the mass of the electron. Source: Internet