Simulation of angular resolved RABBITT measurements in noble gas atoms

TL;DR

This paper presents non-perturbative simulations of angular resolved RABBITT measurements on noble gas atoms, comparing results with RPAE calculations to assess the accuracy of effective potentials and the impact of electron correlation.

Contribution

It introduces a comprehensive simulation approach for RABBITT measurements on noble gases, including phase and amplitude extraction, and evaluates the validity of single-electron models across different atoms.

Findings

Accurate RABBITT simulations for Ne and Ar up to 100 eV above threshold.

Limitations of single active electron approximation in Kr and Xe due to strong correlation.

Comparison with RPAE validates effective potentials for lighter atoms.

Abstract

We simulate angular resolved RABBITT (Reconstruction of Attosecond Beating By Interference of Two-photon Transitions) measurements on valence shells of noble gas atoms (Ne, Ar, Kr, and Xe). Our non-perturbative numerical simulation is based on solution of the time-dependent Schr\"odinger equation for a target atom driven by an ionizing XUV and dressing IR fields. From these simulations we extract the angular dependent magnitude and phase of the RABBITT oscillations and deduce the corresponding angular anisotropy {\beta} parameter and Wigner time delay ${\tau}_W$ for the single XUV photon absorption which initiates the RABBITT process. Said {\beta} and ${\tau}_W$ parameters are compared with calculations in the random phase approximation with exchange (RPAE) which includes inter-shell correlation. This comparison is used to test various effective potentials employed in the one-electron TDSE. In lighter atoms (Ne and Ar), several effective potentials are found to provide accurate simulation of RABBITT measurements for a wide range of photon energies up to 100 eV above the valence shell threshold. In heavier atoms (Kr and Xe), the onset of strong correlation with the d-shell restricts the validity of the single active electron approximation to several tens of eV above the valence shell threshold.