Attosecond electron-spin dynamics in Xe 4d photoionization

TL;DR

This study uses attosecond interferometry and coincidence spectroscopy to explore the real-time electron-spin dynamics during Xe 4d photoionization, revealing two interfering ionization mechanisms with distinct decay times.

Contribution

It introduces a novel real-time measurement approach to study electron-spin dynamics in xenon photoionization, uncovering two distinct ionization pathways and their decay characteristics.

Findings

Identification of a fast-decaying giant dipole resonance (<50 as)

Detection of a longer-lived spin-flip resonance (several hundred as)

Insight into complex electron-spin interactions during photoionization

Abstract

The photoionization of xenon atoms in the 70-100 eV range reveals several fascinating physical phenomena such as a giant resonance induced by the dynamic rearrangement of the electron cloud after photon absorption, an anomalous branching ratio between intermediate Xe$^+$ states separated by the spin-orbit interaction and multiple Auger decay processes. These phenomena have been studied in the past, using in particular synchrotron radiation, but without access to real-time dynamics. Here, we study the dynamics of Xe 4d photoionization on its natural time scale combining attosecond interferometry and coincidence spectroscopy. A time-frequency analysis of the involved transitions allows us to identify two interfering ionization mechanisms: the broad giant dipole resonance with a fast decay time less than 50 as and a narrow resonance at threshold induced by spin-flip transitions, with much longer decay times of several hundred as. Our results provide new insight into the complex electron-spin dynamics of photo-induced phenomena.