Exploring Interatomic Coulombic Decay by Free Electron Lasers

TL;DR

This paper proposes a multiphoton absorption scheme using free electron lasers to efficiently study interatomic Coulombic decay in neon dimers, demonstrating enhanced detection methods and interference effects at various laser intensities.

Contribution

It introduces a novel multiphoton excitation approach for ICD investigation, outperforming traditional single-photon methods and analyzing interference effects at different laser parameters.

Findings

Multiphoton absorption enhances ICD detection efficiency.

Interference effects between ICD electrons and ionization electrons are observed.

Time-delayed measurements can isolate ICD contributions at high intensities.

Abstract

To exploit the high intensity of laser radiation, we propose to select frequencies at which single-photon absorption is of too low energy and two or more photons are needed to produce states of an atom that can undergo interatomic Coulombic decay (ICD) with its neighbors. For Ne dimer it is explicitly demonstrated that the proposed scheme to investigate interatomic processes by multiphoton absorption is much more efficient than with single-photon absorption of sufficiently large frequency as used until now. Extensive calculations on Ne dimer including all the involved nuclear dynamics and the losses by ionization of the participating states show how the low-energy ICD electrons and Ne$^+$ pairs are produced for different laser intensities and pulse durations. At higher intensities the production of Ne$^+$ pairs by successive ionization of the two atoms becomes competitive and the respective emitted electrons interfere coherently with the ICD electrons. It is also demonstrated that a measurement after a time delay can be used to determine the contribution of ICD even at high laser intensity.