The atomic mass of tritium (symbol T or ^3H) can be determined through various methods, including mass spectrometry and nuclear reactions.
One method involves using a mass spectrometer, which is a device that measures the masses and relative abundances of atomic and molecular ions. In the case of tritium, the sample is ionized, and the resulting ions are accelerated and sent through a magnetic field. The ions are deflected by the magnetic field based on their mass-to-charge ratio. By measuring the deflection, the mass-to-charge ratio, and knowing the charge of the ion, the mass of tritium can be determined.
Another method involves nuclear reactions, specifically using tritium as a target in a nuclear reaction with a known stable isotope. For example, tritium can undergo a reaction with a deuteron (^2H) to produce helium-4 (^4He) and a neutron. By measuring the energies and velocities of the resulting particles and applying conservation laws, the mass of tritium can be deduced.
It's important to note that tritium is a radioactive isotope with a half-life of approximately 12.3 years. This means that over time, the amount of tritium in a sample will decrease due to radioactive decay. Therefore, the determination of the atomic mass of tritium may involve correcting for the decay of tritium over the measurement period.
The currently accepted value for the atomic mass of tritium is approximately 3.01604928 atomic mass units (amu).