Nuclear-Electron Correlation Effects and Their Photoelectron Imprint in Molecular XUV Ionisation

Karl Michael Ziems; Jakob Bruhnke; Volker Engel; Stefanie Gräfe

doi:10.3389/fchem.2022.942633

Nuclear-Electron Correlation Effects and Their Photoelectron Imprint in Molecular XUV Ionisation

Front Chem. 2022 Aug 5:10:942633. doi: 10.3389/fchem.2022.942633. eCollection 2022.

Authors

Karl Michael Ziems^{1

2}, Jakob Bruhnke¹, Volker Engel³, Stefanie Gräfe^{1

2

4

5}

Affiliations

¹ Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena, Germany.
² Max Planck School of Photonics, Jena, Germany.
³ Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Würzburg, Germany.
⁴ Abbe Center of Photonics, Friedrich Schiller University, Jena, Germany.
⁵ Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, Germany.

Abstract

The ionisation of molecules by attosecond XUV pulses is accompanied by complex correlated dynamics, such as the creation of coherent electron wave packets in the parent ion, their interplay with nuclear wave packets, and a correlated photoelectron moving in a multi-centred potential. Additionally, these processes are influenced by the dynamics prior to and during the ionisation. To fully understand and subsequently control the ionisation process on different time scales, a profound understanding of electron and nuclear correlation is needed. Here, we investigate the effect of nuclear-electron correlation in a correlated two-electron and one-nucleus quantum model system. Solving the time-dependent Schrödinger equation allows to monitor the correlation impact pre, during, and post-XUV ionisation. We show how an initial nuclear wave packet displaced from equilibrium influences the post-ionisation dynamics by means of momentum conservation between the target and parent ion, whilst the attosecond electron population remains largely unaffected. We calculate time-resolved photoelectron spectra and their asymmetries and demonstrate how the coupled electron-nuclear dynamics are imprinted on top of electron-electron correlation on the photoelectron properties. Finally, our findings give guidelines towards when correlation resulting effects have to be incorporated and in which instances the exact correlation treatment can be neglected.

Keywords: TDSE; XUV; attosecond dynamics; correlation effects; entanglement; photoelectron spectrum; photoionisation; ultrafast phenomena.