Strong interference effects in the resonant Auger decay of atoms induced by intense X-Ray fields

TL;DR

This paper develops a theoretical framework to understand how intense X-ray fields influence resonant Auger decay in atoms, revealing strong interference effects and new spectral patterns due to competing ionization processes.

Contribution

It introduces a comprehensive theory accounting for coupling, decay, and ionization processes in high-intensity X-ray induced Auger decay, highlighting interference effects in electron spectra.

Findings

Interference effects become prominent at high field intensities.

Distinct spectral patterns emerge for participator and spectator decay channels.

The theory explains the impact of direct photoionization on Auger electron spectra.

Abstract

The theory of resonant Auger decay of atoms in a high intensity coherent X-ray pulse is presented. The theory includes the coupling between the ground state and the resonance due to an intense X-ray pulse, taking into account the decay of the resonance and the direct photoionization of the ground state, both populating the final ionic states coherently. The theory also considers the impact of the direct photoionization of the resonance state itself which typically populates highly-excited ionic states. The combined action of the resonant decay and of the direct ionization of the ground state in the field induces a non-hermitian time-dependent coupling between the ground and the 'dressed' resonance stats. The impact of these competing processes on the total electron yield and on the 2s$^2$2p$^{4}(^1\mathrm{D})$3p $^2$P spectator and 2s$^1$2p$^{6}$ $^2$S participator Auger decay spectra of the Ne 1s$\to$3p resonance is investigated. The role of the direct photoionization of the ground state and of the resonance increases dramatically with the field intensity. This results in strong interference effects with distinct patterns in the electron spectra, different for the participator and spectator final states.