The diatomic dication PO2+.

The diatomic dication PO(2+) has been generated by the sputtering of surface-oxidized InP wafers and by electron ionization of gaseous trimethyl phosphate. According to ab initio calculations, the dication PO(2+) is metastable with respect to dissociation into P(+) + O(+), and the calculated ionization energy of the PO(+) monocation to form the dicationic species is ca. 22.6 eV. The potential energy functions for the ground state and twelve low-lying excited electronic states of the PO(2+) dication have been calculated using high-level ab initio methods with adiabatic excitation energies of PO(2+), spectroscopic constants and the ionization energies of PO and PO(+) being determined. Upon collision with xenon, electron transfer to PO(2+) takes place to form the PO(+) monocation together with a small amount of dissociative electron transfer to form P(+). Upon collisions of PO(2+) with deuterium, charge separation is accompanied by a bond-forming reaction to yield monocationic POD(+).