Magnetic-field effect in high-order above-threshold ionization

TL;DR

This study explores how magnetic fields influence high-order above-threshold ionization in xenon atoms, revealing new momentum shift behaviors and the impact of electron rescattering on photon momentum distribution.

Contribution

It provides the first observation of a V-shape nondipole shift above the classical cutoff and combines experimental and theoretical analysis to understand magnetic effects in strong-field ionization.

Findings

V-shape nondipole shift above the cutoff identified

Large-angle rescattering alters photon momentum partitioning

Nondipole shift sensitivity depends on atomic electronic structure

Abstract

We experimentally and theoretically investigate the influence of the magnetic component of an electromagnetic field on high-order above-threshold ionization of xenon atoms driven by ultrashort femtosecond laser pulses. The nondipole shift of the electron momentum distribution along the light-propagation direction for high energy electrons beyond the classical cutoff is found to be vastly different from that below the cutoff. A V-shape structure in the momentum dependence of the nondipole shift above the cutoff is identified for the first time. With the help of classical and quantum-orbit analysis, we show that large-angle rescattering of the electrons strongly alters the partitioning of the photon momentum between electron and ion. The sensitivity of the observed nondipole shift to the electronic structure of the target atom is confirmed by three-dimensional time-dependent Schr\"odinger equation simulations for different model potentials.