Applications

These hafnium and tantalum isomers have been considered in some quarters as weapons that could be used to circumvent the Nuclear Non-Proliferation Treaty, since they can be induced to emit very strong gamma radiation. DARPA has or has had a program to investigate this usage of both isomers. However, given the difference in speed between a photon and a neutron, they can't be induced to chain react like a nuclear weapon, so there will probably never be such a weapon. Ta-180m is also one of the most expensive substances to procure in the world: It costs approximately $17 million per gram. In 1999, the entire world's supply of Ta-180m was only 6.7 milligrams.Technetium isomers Tc-99m (with a half-life of 6.01 hours) and Tc-95m (with a half-life of 61 days) are used in medical and industrial applications.