 However, the isobar with atomic number two higher, selenium-76, has a larger binding energy, so double beta decay is allowed.The emission spectrum of the two electrons can be computed in a similar way to beta emission spectrum using Fermi's Golden Rule.The differential rate is given by

where the subscripts refer to each electron, is kinetic energy, is total energy, is the Fermi Function with "Z" the charge of the final-state nucleus, is momentum, is velocity in units of , is the angle between the electrons, and is the Q value of the decay.