Electron angular distribution in near-threshold double photoionization: extended Wannier ridge model

In order to account properly for the dynamics of the electron angular correlations near the double ionization threshold the extended Wannier model is formulated in which the electrons recede from the reaction zone being at equal distances from the nucleus but in arbitrary directions. ¹S^e and ¹P^o states of the two-electron continuum are considered. The boundary conditions on the border of the reaction zone are imposed corresponding to the double photoionization process. The wavepacket propagation to the free electron regime is calculated numerically. The asymmetry parameter beta is in good agreement with recent experiments.