CALCULATION OF RESONANT STRUCTURE OF A DOUBLE PHOTOIONIZATION

Using many-body perturbation theory, we give the first calculation for ;the resonance structure into the double photoionization continuum in the 2s --> 3p resonance region in neutral sodium. This resonance struc ture results from the interference between the one step direct double photoionization continuum and the resonant Auger process. The coupled equation method has been improved to calculate this interference by th e summation of specific classes of diagrams of perturbation theory to infinite order. We find that the dominant contribution to resonance co mes from a super-Coster-Kronig decay. Theoretical results are in good agreement with experiment. (C) 1997 Elsevier Science B.V.