Influence of the Coulomb potential on above-threshold ionization: a quantum-orbit analysis beyond the strong-field approximation

TL;DR

This paper investigates how the Coulomb potential affects above-threshold ionization by extending the strong-field approximation with Coulomb corrections, revealing its influence on electron trajectories and ATI spectra.

Contribution

It introduces a Coulomb-corrected SFA that incorporates the Coulomb potential into electron propagation, providing new insights into ATI features beyond standard models.

Findings

Coulomb interaction lifts degeneracy of SFA trajectories

Identification of rescattering-related orbits at high energies

Good agreement with ab initio Schrödinger equation solutions

Abstract

We perform a detailed analysis of how the interplay between the residual binding potential and a strong laser field influences above-threshold ionization (ATI), employing a semi-analytical, Coulomb-corrected strong-field approximation (SFA) in which the Coulomb potential is incorporated in the electron propagation in the continuum. We find that the Coulomb interaction lifts the degeneracy of some SFA trajectories, and we identify a set of orbits which, for high enough photoelectron energies, may be associated with rescattering. Furthermore, by performing a direct comparison with the standard SFA, we show that several features in the ATI spectra can be traced back to the influence of the Coulomb potential on different electron trajectories. These features include a decrease in the contrast, a shift towards lower energies in the interference substructure, and an overall increase in the photoelectron yield. All features encountered exhibit a very good agreement with the \emph{ab initio} solution of the time-dependent Schr\"odinger equation.