State-selective study of the direct double photoionization of the Ne valence shell

Cross sections for double photoionization of the Ne L shell into the 2s2p 5 3 P 0 and 1 P 0 and the 2s 0 2p 6 1 S e states were measured for energies from threshold up to 150 eV, using photon induced fluorescence spectroscopy. Both 2s2p 5 channels were observed with comparable magnitude in contradiction to a propensity rule based on the Wannier-Peterkop-Rau theory. A comparison of the summed 3 P 0 and 1 P 0 cross sections with MBPT calculations results in a deviation of 50%.