Coulomb Rescattering in Nondipole Interaction of Atoms with Intense Laser Fields

TL;DR

This paper explores how Coulomb rescattering influences electron dynamics in atoms exposed to intense laser fields, revealing non-dipole effects and predicting specific momentum distribution features beyond traditional approximations.

Contribution

It introduces a semiclassical model including magnetic Lorentz force to explain non-dipole effects in ionization, providing quantitative predictions aligned with recent experiments.

Findings

Identification of a bright spot in transverse momentum distribution.

Prediction of a nonzero momentum peak opposite to laser propagation.

Explanation of the anti-intuitive peak mechanism in rescattering dynamics.

Abstract

We investigate the ionization dynamics of atoms irradiated by an intense laser field using a semiclassical model that includes magnetic Lorentz force in the rescattering process. We find that, the electrons tunneled with different initial transverse momenta (i.e., perpendicular to the instantaneous electric field direction) distributed on a specific circle in the momentum plane can finally converge to the same transverse momentum after experiencing Coulomb forward scattering. These electron trajectories lead to a bright spot structure in the 2D transverse momentum distribution, and particularly in the long-wavelength limit, a nonzero momentum peak in the direction antiparallel to the laser propagation (or radiation pressure) direction. Making analysis of the subcycle dynamics of rescattering trajectories, we unveil the underlying mechanism of the anti-intuitive peak. Beyond the strong field approximation and the dipole approximation, we quantitatively predict the spot center and the peak position. Our results are compared with a recent experiment and some theoretical predictions are given.