No abstract

Triple differential cross sections (TDCS) for double photoionization in H2 and D2 (for comparison also in helium) have been measured for equal energy sharing, E 1 = E 2 = 10 eV. In agreement with previous observations by the Reddish group and in comparison to the equivalent helium case, our D2 data confirm a `narrowing' effect in the correlation factor which influences the observed TDCS lobes, as well as a `filling-in' effect at relative angles θ1,2 = 180°. However, we do not confirm the previous differences in the magnitude of D2 and H2 TDCS values. Instead, we get equal TDCS strengths and, in comparison to helium, reasonable agreement with the corresponding total cross section ratio for double photoionization in He and D2.

Postcollision interaction effects have been investigated for sequential two-electron emission in xenon for particular kinematical conditions, small relative angles between the emitted electrons, and selected energies e a e b which are halfway in between the nominal values of the "photo"-electron and the "Auger" electron. The experimental results are in good agreement with the theoretical prediction. Our successful technique to measure two coincident electrons of nearly the same energy and the same directions opens a plethora of possibilities to probe for different cases the Coulomb interaction of three charged particles and the impact of the intermediate resonance state. [S0031-9007(99)09343-6] PACS numbers: 32.80.Hd

The three-body Coulomb interaction in sequential photo double-ionization, frequently called post-collision interaction (PCI), can lead to a collapse of transition probability if the relative angle between the emitted electrons approaches zero. We have studied this effect for a specially selected atomic system, 4d5/2 photoionization in xenon with subsequent N5–O2,3O2,31S0 Auger decay, and compared the experimental data with results from a quantum mechanical PCI calculation and a classical PCI model.

Abstract. Within the dipole approximation and the LS-coupling limit 3p photoionization in atomic calcium is described completely by two matrix elements and one relative phase. These three parameters are extracted from experimental observables and compared with theoretical calculations (RRPA transformed to the non-relativistic limit) for photon energies around the Cooper minimum in the 3p → d channel. Taking into account the intensity-borrowing model, excellent agreement between theoretical and experimental data is found.