Isometric Transition

Isomeric transition is a radioactive decay process that occurs in an atom where the nucleus is in an excited meta-state (e.g. following the emission of an alpha or beta particle). The extra energy in the nucleus is released by the emission of a gamma ray, returning the nucleus to the ground state. This process is similar to a gamma emission but differs in that it involves excited meta-states.

The gamma ray may transfer its energy directly to one of the most tightly bound electrons causing it to be ejected from the atom, a process termed internal conversion.