Nikolai L. Manakov

Nondipole Effects in Double Photoionization of He

Lowest‐order nondipole effects are studied in double photoionization (DPI) of the He atom. Ab initio parametrizations of the quadrupole transition amplitude for DPI from the 1S0‐state are presented in terms of the exact two‐electron reduced matrix elements. Parametrizations for the dipole‐quadrupole triply differential cross section (TDCS) and doubly differential cross section (DDCS) are presented in terms of polarization‐independent amplitudes for the case of an elliptically polarized photon. Expressions for the DDCS in terms of the reduced two‐electron matrix elements are also given. A general analysis of retardation‐induced asymmetries of the TDCS including the circular dichroism effect at equal energy sharing is presented. Our numerical results exhibit a nondipole forward‐backward asymmetry in the TDCS for DPI of He at an excess energy of 450 eV that is in qualitative agreement with existing experimental data.

Polarization and initial state symmetry dependence of strong field atomic processes

An exact quantum analysis of the polarization and initial state symmetry dependence of intense laser interactions with an electron that is weakly bound in a short-range potential is shown to provide qualitative insights into and quantitative estimates for some key features of strong field atomic processes.