Contrôle de la dynamique électronique attoseconde
dans les systèmes moléculaires : de LiH à ABCU (C10H19N)
Pr. Françoise Remacle Laboratoire de Chimie Physique Théorique
Université de Liège - Belgique
Mercredi 6 juin à 11h, bibliothèque LCT, tour 12-13, 4e étage
The atto-second time-scale electronic dynamics induced by an ultra-short laser pulse is computed at the time-dependent multi-configurational level in the diatomic molecule LiH(1) and in ABCU (C10H19N),(2) a medium size polyatomic molecule with a rigid cage geometry. The coupling between the electronic states induced by the strong pulse is included in the Hamiltonian. The ultra-short pump pulse excites a coherent superposition of stationary electronic states. As a result, observables sensitive to interferences like the electron density and the dipole moment beat in time. We show that by changing the pump parameters such as intensity, duration, polarization and phase of carrier frequency one can control the motion of the electrons and the localization of the electron density in different parts of the molecule, both during and after the pulse. The pulse polarization in particular allows for the control the electronic stereo-dynamics both in LiH and in ABCU. The spatial beatings of the electronic density can be probed by sudden ionization by an ultra-short XUV pulse.
We will present computed molecular frame photoelectron angular distributions (MFPAD) that illustrate how the specificity of the time dependence of electron localization depends on the nature of the superposition of electronic states that is built at the end of the excitation pulse. Special emphasis will be given to the role of the interference terms in modulating the angular distributions of the photoionization cross-section.