On the production of N+2 ions at the N 1s edge of the nitrogen molecule

The N+2 ion yield of the N2 molecule has been measured at the N 1s!Rydberg excitations. It displays Fano-type line shapes due to interference between direct outer-valence photoionization and participator decay of the core-excited Rydberg states. The N+2 ion yield is compared with the total intensity of the outer-valence photoelectron lines obtained recently with electron spectroscopy (Kivim¨aki et al 2012 Phys. Rev. A 86 012516). The increasing difference between the two curves at the higher core-to-Rydberg excitations is most likely due to soft x-ray emission processes that are followed by autoionization. The results also suggest that resonant Auger decay from the core-valence doubly excited states contributes to the N+2 ion yield at the photon energies that are located on both sides of the N 1s ionization limit.