X-ray emission-photoion coincidence spectroscopy of the CO2 molecule at the O 1s edge

► Fragmentation of CO2 has been studied after soft X-ray emission from O 1s hole states. ► X-ray emission-photoion coincidence (XEPICO) technique is introduced. ► De-excitation pathways leading to the observed ions in XEPICO spectra are discussed. ► Observation of the CO22+ ion is attributed to the radiative Auger effect.