Relativistic mask method for electron momentum distributions after ionization of hydrogen-like ions in strong laser fields

TL;DR

This paper extends the wavefunction-splitting or mask method to the relativistic regime within the dipole approximation, enabling accurate calculation of electron momentum distributions after ionization of hydrogen-like ions in strong laser fields.

Contribution

It develops a relativistic mask method by numerically constructing Volkov states, allowing for efficient and accurate electron distribution calculations in relativistic ionization regimes.

Findings

Relativistic mask method accurately reproduces direct calculation results.

Method is effective for longer laser pulses and higher electron energies.

Relativistic mask method extends applicability of wavefunction-splitting techniques.

Abstract

Wavefunction-splitting or mask method, widely used in the non-relativistic calculations of the photoelectron angular distributions, is extended to the relativistic domain within the dipole approximation. Since the closed-form expressions for the relativistic Volkov states are not available within the dipole approximation, we build such states numerically solving a single second-order differential equation. We calculate the photoelectron energy spectra and angular distributions for highly charged ions under different ionization regimes with both the direct and the relativistic mask methods. We show that the relativistic mask method works very well and reproduces the electron energy and angular distributions calculated by the direct method in the energy range where both methods can be used. On the other hand, the relativistic mask method can be applied for longer laser pulses and/or higher photoelectron energies where the direct method may have difficulties.