Dication
A dication is any cation, of general formula X, formed by the removal of two electrons from a neutral species.
Diatomic dications corresponding to stable neutral species (e.g. H2+
2 formed by removal of two electrons from H2) often decay quickly into two singly charged particles (H), due to the loss of electrons in bonding molecular orbitals. Energy levels of diatomic dications can be studied with good resolution by measuring the yield of pairs of zero-kinetic-energy electrons from double photoionization of a molecule as a function of the photoionizing wavelength (threshold photoelectrons coincidence spectroscopy – TPEsCO). The He2+
2 dication is kinetically stable.