Decay of the(2s22p)P2Compound State in Helium by Two-Electron Emission

Compound states of atoms are known to decay by the emission of a single electron into many states lying at lower energies. Compound states associated with doubly excited states lie at energies above the ionization potential, and therefore the decay into an ion by the emission of two electrons is energetically possible. This paper presents evidence for such a two-electron decay in the case of the $\left(2\mathrm{}{s}^{2}2p\right){}_{}{}^2{}_{}{}^{}P$ compound state of helium which derives from the $\left(2\mathrm{}{s}^2\right){}_{}{}^1{}_{}{}^{}S$ atomic state.