Speaker
Description
The broad energy bandwidth of ultrashort pulses enables building a coherent superposition of elec-tronic states. As a result, the electronic density is out of equilibrium and its localization between nuclei can be controlled on a purely electronic time scale.[1] As the nuclei begin to move, the electronic and nuclear motions are entangled.[2] This entanglement can be usefully exploited for controlling the force exerted by the vibronic wave packet on the nuclei [3] and steering chemical reactivity for bond making and fragmentation.[4,5] The dynamics of entanglement will be discussed for oriented molecules: The photoexcited bound N2 molecule and the LiH molecule whose excited states are dissociating. The role of entanglement will be then discussed in polyatomic molecules undergoing structural rearrangements: Bond making in the photoinduced isomerization of norbornadiene into quadricyclane(4), the structural Jahn-Teller rearrangement of the methane cation upon sudden photoionization(5). Control schemes exploiting electronic coherences are not limited to oriented the molecules. We will show that it can be implemented in ensemble of molecules with initial random orinentations with respect to the pulse po-larization. The principal orientations of the ensemble are characterized using Singular Value Decom-position (SVD).[6] SVD provides insights on the stereodynamics. The approach will be illustrated for the case of an ensemble of initially randomly oriented LiH molecules photoexcited by a short CEP controlled IR pulse and for the forces driving the ultrafast Jahn-Teller (JT) structural rearrangement of the methane cation induced by XUV photoionization.
[1]. F. Remacle et al Proc. Natl. Acad. Sci. USA 103, 6793 (2006).
[2]. M. Blavier et al Phys. Chem. Chem. Phys. 24, 17516 (2022).
[3]. M. Cardosa et al J. Phys. B 57, 133501(2024).
[4]. A. Valentini et al Phys. Chem. Chem. Phys. 22, 22302 (2020).
[5]. C.E.M. Gonçalves, et al Phys. Chem. Chem. Phys. 23 12051 (2021).
[6]. M. Cardosa et al J. Phys. Chem. A. 128, 2937 (2024).
