Photoelectron spectra in strong-field ionization by a high frequency field

TL;DR

This paper compares different theoretical approaches to analyze atomic photoelectron momentum distributions in high-frequency laser fields, highlighting the accuracy of the velocity gauge SFA and discussing the failure of SCVA.

Contribution

It provides a detailed comparison of SFA, SCVA, and ab initio methods in the high-frequency regime, emphasizing the conditions under which each approach is accurate.

Findings

Velocity gauge SFA agrees well with ab initio results.

SCVA fails to match ab initio results in this regime.

High-frequency regime simplifies the analysis of ionization processes.

Abstract

We analyze atomic photoelectron momentum distributions induced by bichromatic and monochromatic laser fields within the strong field approximation (SFA), separable Coulomb-Volkov approximation (SCVA), and ab initio treatment. We focus on the high frequency regime -- the smallest frequency used is larger than the ionization potential of the atom. We observe a remarkable agreement between the ab initio and velocity gauge SFA results while the velocity gauge SCVA fails to agree. Reasons of such a failure are discussed.