Coulomb-corrected strong-field approximation for the two-electron atom

Abstract

We present the model accounting for the Coulomb effects that occur in the direct double photoionization of the two-electron atom in an intense field of a circularly polarized plane wave. The model is the strong-field approximation (SFA) (the Reiss version of Keldysh-type models) applied to helium. We improve here our earlier study by inserting the electron-electron correlation in the initial state of the atom, and by inserting the Coulomb correction due to the influence of the nucleus on the final state of ionized electrons` pair. While the former improvement is of little significance, the latter extends the applicability range of the SFA (for typical laser wavelengths), and causes appreciable growth of the total ionization rate. {copyright} {ital 1997} {ital The American Physical Society}