New approach for a complete experiment: C1s photoionization in CO2 molecules

A new experimental approach for determining the photoionization matrix elements with the use of multi-coincidence velocity-map imaging spectrometry is presented for the case of C1s photoionization of CO2 molecule over the energy region of a shape resonance. Our experimental results provide the complete information on the shape resonance mechanism and clearly demonstrate the inadequacy of presently available theoretical calculations for this system.