Collective resonances of atomic xenon from the linear to the nonlinear regime

TL;DR

This paper investigates the complex collective resonance states of atomic xenon across linear and nonlinear regimes, revealing hidden substructures and predicting long-lived multipole resonances with implications for advanced spectroscopy.

Contribution

It introduces a novel approach analyzing resonance eigenstates to uncover hidden substructures and predicts long-lived multipole resonances in xenon beyond linear spectroscopy.

Findings

Linear spectroscopy captures only partial resonance information due to quantum interference.

The dominant GDR resonance state in linear spectroscopy is not adiabatically connected to the one in the absence of multielectron interactions.

Predicted long-lived multipole resonances exceeding 100 attoseconds.

Abstract

XUV nonlinear spectroscopy has recently discovered that there is more than one collective dipole resonance state in the energy range of the giant dipole resonance (GDR) of atomic Xe. This resonance-state substructure, hidden in the linear regime, raises imminent questions regarding our understanding of the collective electronic behavior of Xe, which has been largely founded on linear spectroscopic studies. Here, we approach the collective response of Xe from a new perspective: we study directly the resonance eigenstates, and then analyze their spectroscopic manifestations. We find that linear spectroscopy captures only partial information on the resonance substructure as a result of quantum interferences. Moreover, we show that the resonance state dominating the GDR in linear spectroscopy has no adiabatic connection to the resonance state governing the corresponding cross section when multielectron interactions are neglected. Going beyond the dipole-allowed correlated electronic structure, we predict the existence of collective multipole resonances of Xe. Unlike any known collective feature in atoms, these resonances live exceptionally long (more than 100 attoseconds), thus providing a new playground for studying the collective nonlinear response of Xe using advanced light sources.