Dynamics of electron emission in double photoionization processes near the Krypton 3d threshold

Two electron emission following photoabsorption near the Kr 3d threshold is investigated both experimentally and theoretically. On the experimental side, electron/electron coincidences using a magnetic bottle time of flight spectrometer allow us to observe the complete Double Photo Ionisation (DPI) continua of selected Kr²⁺ final states, and to see how these continua are affected by resonant processes in the vicinity of the Kr 3d threshold. The analysis is based on a quantum mechanical approach that takes into account the contribution of three different processes: A) Auger decay of the inner 3d vacancy with the associated post collision interaction (PCI) effects, B) capture of slow photoelectrons into discrete states followed by valence multiplet decay (VMD) of the excited ionic states and C) valence shell DPI. The dominant process for each Kr²⁺(4p^-2) final state is the photoionization of the inner shell followed by Auger decay of the 3d vacancies. Moreover, for the 4p²(³P) and 4p^-2(¹D) final ionic states an important contribution comes from the processes of slow photoelectron capture followed by VMD as well as from double ionization of the outer shell involving also VMD