Nondipole Coulomb sub-barrier ionization dynamics and photon momentum sharing

Pei-Lun He,Christoph H Keitel,Michael Klaiber,Karen Z Hatsagortsyan

doi:10.1103/physreva.105.l031102

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.

Highlights

Exchanges of photon’s energy, momentum, and angular momentum with charged particles are fundamental building blocks of light-matter interactions
It follows from energy and momentum conservation that in the simple-man model of tunneling ionization [2], when the electron appears in the continuum with a vanishing momentum due to a circularly polarized laser pulse, the total absorbed photon momentum is shared between the ion and electron as Ip/c and Up/c, respectively [11,20], where Ip is the ionization energy, Up the ponderomotive potential, and
The Coulomb field of the atomic core reshapes the tunneling barrier and, the nondipole momentum shift due to the sub-barrier dynamics. The latter is affected by the momentum distribution of the bound state, which contributes into the birth probability of the quantum orbit at vzs

Summary

Introduction

Exchanges of photon’s energy, momentum, and angular momentum with charged particles are fundamental building blocks of light-matter interactions. The Coulomb field of the atomic core reshapes the tunneling barrier and, the nondipole momentum shift due to the sub-barrier dynamics. In this Letter, we investigate the electron’s sub-barrier nondipole dynamics in strong-field tunneling ionization within an enhanced analytical description including the role of the Coulomb field of the atomic core.

Results

Conclusion