Nondipole Coulomb sub-barrier ionization dynamics and photon momentum sharing
Pei-Lun He, Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel
Abstract
The nondipole under-the-barrier dynamics of the electron during strong-field tunneling ionization is investigated, examining the role of the Coulomb field of the atomic core. The common analysis in the strong-field approximation is consequently generalized to include the leading light-front nondipole Coulomb corrections and demonstrates the counterintuitive impact of the sub-barrier Coulomb field. Despite its attractive nature, the sub-barrier Coulomb field increases the photoelectron nondipole momentum shift along the laser propagation direction, involving a strong dependence on the laser field. The scaling of the effect with respect to the principal quantum number and angular momentum of the bound state is found. We demonstrate that the signature of Coulomb induced sub-barrier effects can be identified in the asymptotic photoelectron momentum distribution via a comparative study of the field-dependent longitudinal momentum shift for different atomic species with state-of-the-art experimental techniques of midinfrared lasers.