Attosecond photoionization dynamics in the vicinity of the Cooper minima in argon

TL;DR

This study measures and analyzes the attosecond-scale photoionization time delays in argon near Cooper minima, providing experimental data that tests and refines multielectronic theoretical models of electron dynamics.

Contribution

It presents the first spectrally resolved measurements of photoionization delays in argon across the Cooper minima, including the effects of shake-up channels, and compares them with advanced theoretical calculations.

Findings

Observed strong variation and sign change in delay differences near Cooper minima.

Experimental data agrees with Two-Photon Two-Color RPAE calculations when shake-up channels are included.

Provides a benchmark for multielectronic theoretical models of electron correlation.

Abstract

Using a spectrally resolved electron interferometry technique, we measure photoionization time delays between the $3s$ and $3p$ subshells of argon over a large 34-eV energy range covering the Cooper minima in both subshells. The observed strong variations of the $3s-3p$ delay difference, including a sign change, are well reproduced by theoretical calculations using the Two-Photon Two-Color Random Phase Approximation with Exchange. Strong shake-up channels lead to photoelectrons spectrally overlapping with those emitted from the $3s$ subshell. These channels need to be included in our analysis to reproduce the experimental data. Our measurements provide a stringent test for multielectronic theoretical models aiming at an accurate description of inter-channel correlation.