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

C Alexandridi,M Turconi,C L Arnold,P Salières,J.-F Hergott,M Gisselbrecht,A Borot,S Zhong,L Neoričić,E Lindroth,D Busto,H Laurell,A L'Huillier,D Platzer,O Tcherbakoff,L Barreau,J M Dahlström,M Lejman

doi:10.1103/physrevresearch.3.l012012

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.

Highlights

Half a century after their theoretical description by Eisenbud [1], Wigner [2], and Smith [3], scattering delays— called Wigner delays—can be measured using attosecond spectroscopy, which allows for detailed studies of the correlated interactions within various quantum systems
3s subshell, interorbital correlation is important, since the 3p → εd process is strongly coupled to 3s → ε p [35]. This leads to a correlation-induced “replica” of the 3p Cooper minima (CM) in the 3s ionization channel, close to 42-eV photon energy, as shown in Fig. 1 [36]. All these correlation effects are expected to leave an imprint on the scattering and photoionization delays between the 3s and 3p electrons, which motivated a large number of calculations during the past decade in the demanding region above the 3s threshold [11,12,37,38,39,40,41,42,43,44,45]
The methods qualitatively agree on the behavior of the 3p atomic delays, which are slightly negative over a large energy region around the 3p CM

Summary

Introduction

Half a century after their theoretical description by Eisenbud [1], Wigner [2], and Smith [3], scattering delays— called Wigner delays—can be measured using attosecond spectroscopy, which allows for detailed studies of the correlated interactions within various quantum systems. This leads to a correlation-induced “replica” of the 3p CM in the 3s ionization channel, close to 42-eV photon energy, as shown in Fig. 1 [36].

Results

Conclusion