Site-specific formation of metastable dications following inner-shell ionization of CO2

An Auger-electron–ion coincidence method is applied to study the site-specific formation of metastable CO22+ in the C1s and O1s Auger decays of CO2. It is found that only dication states with the electronic configuration of 1πg−2 are relevant to the metastable formation. These dication states are favorably produced in the O1s Auger decay, because of the charge distribution of the 1πg orbital localizing at the O site. Fragmentation channels of dissociative CO22+ states are also investigated.