Interference modulation in the vibrationally resolved photoionization of the 1σg and 1σu core levels of the N2 molecule

The ratios of photoionization cross sections of the 1 sigma(g) and 1 sigma(u) shells of the N-2 molecule for the vibrational transitions to the nu' = 0 and nu' = 1 core-ionized states in the photon energy region between 440 and 550 eV have been measured. The calculations in the random phase approximation well reproduce the experimental data. The variation of the ratio with photon energy is attributed to the interference modulation that is caused by coherent photoemission from the two atoms, as an analogue of the Young's double-slit experiment. The calculations extended up to 1.8 keV allow connecting the modulation with the onset of transitions to the states of increasing orbital angular momentum which occurs at increasing photon energies and demonstrate that the main contribution to these modulations comes from the alpha continuum states.