2 ELECTRON ONE-PHOTON TRANSITIONS IN ATOMIC SYSTEMS

Excitation energies and transition probabilities for two electron one photon (K-alpha alpha) transition 2s(2)2p(6): S-1 -> (1)s(2) 2s2p(5):P -1 have been estimated for the inner shell ionised atoms Ne, Na, Mg, A l, Si, P, S, Cl and Ar. Similar transition data have also been evaluat ed for K-alpha alpha(s) transition 2s2p: P-1 -> 1s(2): S-1 of the high ly stripped He like ions Ne8+, Na9+, Mg10+, Al11+, Si12+, P13+, S14+, Cl15+ and Ar16+. The branching ratio between the X-ray hypersatellite line K-alpha 2(h) (2s(2)2p(6): S-1 -> 1s2s(2)2p(5): P-1) and K-alpha a lpha line and that between K-alpha 2(h) and K-alpha alpha(s) transitio n has been estimated for all these ions. The method is based on variat ional principle with a correlated description of the initial and final states. Most of the data are new and agreement is very reasonable wit h the few available data.