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 ^1P^0 and the 2s^02p^6 ^1S^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 ^3P^0 and ^1P^0 cross sections with MBPT calculations results in a deviation of 50%.

Ground state correlation energy of the Be-sequence for Z = 4-20 in MCDF approximation

The ground state (J = 0) electronic correlation energy of the 4-electron Be-sequence is calculated in the Multi-Configuration Dirac-Fock approximation for Z = 4-20. The 4 electrons were distributed over the configurations arising from the 1s, 2s, 2p, 3s, 3p and 3d orbitals. Theoretical values obtained here are in good agreement with experimental correlation energies.