Electron correlation and electro-nuclear couplings in the dissociative-ionization dynamics of molecules in intense laser fields

This work focuses on the study of the complete molecular dynamics of the H2 molecule exposed to an intense laser field.

The first part of this study investigates the role of electronic correlations in the single ionization process. For this purpose, the Many-Electron-Dynamics System (MEDYS) program has been adapted. This program results from decades of work in the group of Professor Nguyen-Dang at the University Laval (Canada). The time-dependent multi-configuration algorithm used has been modified to introduce an adiabatic switch-off of the electronic correlation. The results of the dynamics, including the Coulomb forces between all particles, were compared with those of the dynamics with the correlation switched-off, thus laying the foundation for an assessment of the quantitative limits of the Single Active Electron (SAE) approximation, which neglects this correlation.

In the second part of this study, semiclassical approximations are used to model the ionization process. This new approach has allowed to study the influence of the method (molecular ADK or molecular PPT) and the field polarization (linear or circular) on the non-Franck-Condon distribution of the ionized population towards H₂⁺. This simplification of the calculation of the ionization process facilitated the integration of nuclear vibrational dynamics in a new version of the code, using a split-operator routine to propagate H₂ and H₂⁺ wave packets along the internuclear coordinate. Comparison of the dynamics of static and propagated wavepackets confirmed the importance of vibrational motion in the dynamics of molecular ionization. In addition, the kinetic energy distribution (KED) spectra of the protons produced by H2+ dissociation and during the Coulomb explosion (into 2 H⁺) were analyzed. These results pave the way for a potential collaboration with plasma physics experimentalists, providing them with a fast and realistic estimation of the KED spectra.

Membres du jury :
 Prof. Anh-Thu Le (University of Connecticut)
 Dr. Richard Taïeb (Sorbonne Université)
 Dr. Christian Cornaggia (CEA Saclay)
 Prof. Paul Johnson (Université Laval)

Directeurs de cotutelle :
 Prof. Eric Charron (Université Paris-Saclay)
 Prof. Thanh-Tung Nguyen-Dang (Université Laval)
- Dr. Osman Atabek (Université Paris-Saclay)