Temporal characterization of electron dynamics in attosecond XUV and infrared laser fields

TL;DR

This paper investigates the electron dynamics during ionization by XUV and IR laser fields using a Wigner distribution approach, revealing how the IR field influences emission timing and energy distributions, with implications for attosecond physics.

Contribution

It introduces a Wigner distribution-based method to analyze time-energy distributions of ionized electrons in combined XUV and IR fields, highlighting the role of interference and field effects.

Findings

Electron emission timing depends on pulse phase and emission direction.

IR field modifies electron kinetic energy and emission time.

Higher ionization energy atoms show less IR influence on electron dynamics.

Abstract

We use a Wigner distribution-like function based on the strong field approximation theory to obtain the time-energy distributions and the ionization time distributions of electrons ionized by an XUV pulse alone and in the presence of an infrared (IR) pulse. In the case of a single XUV pulse, although the overall shape of the ionization time distribution resembles the XUV-envelope, its detail shows dependence on the emission direction of the electron and the carrier-envelope phase of the pulse, which mainly results from the low-energy interference structure. It is further found that the electron from the counter-rotating term plays an important role in the interference. In the case of the two-color pulse, both the time-energy distributions and the ionization time distributions change with varying IR field. Our analysis demonstrates that the IR field not only modifies the final electron kinetic energy but also changes the electron's emission time, which results from the change of the electric field induced by the IR pulse. Moreover, the ionization time distributions of the photoelectrons emitted from atoms with higher ionization energy are also given, which show less impact of the IR field on the electron dynamics.