Resolving Ultra-Fast Spin-Orbit Dynamics in Heavy Many-Electron Atoms

TL;DR

This paper employs advanced R-Matrix with Time-dependence theory including spin-orbit effects to control and observe autoionising states in krypton atoms using two delayed ultrashort XUV pulses.

Contribution

It introduces a novel application of RMT theory with spin-orbit effects to study and manipulate autoionising states in heavy many-electron atoms with ultrafast pulses.

Findings

Controlled excitation pathways via pulse delay variation

Isolation of two-photon excitation pathway using cross-polarised pulses

Observation of autoionising state decay dynamics

Abstract

We use R-Matrix with Time-dependence (RMT) theory, with spin-orbit effects included, to study krypton irradiated by two time-delayed XUV ultrashort pulses. The first pulse excites the atom to 4s$^{2}$4p$^{5}$5s. The second pulse then excites 4s4p$^{6}$5s autoionising levels, whose population can be observed through their subsequent decay. By varying the time delay between the two pulses, we are able to control the excitation pathway to the autoionising states. The use of cross-polarised light pulses allows us to isolate the two-photon pathway, with one photon taken from each pulse.