Role of electronic coherences in ultrafast non-equilibrium quantum dynamics in molecules induced by strong short optical pulses

Datum

30.05.2018

Zeit

16:30 - 17:30

Sprecher

Francoise Remacle

Zugehörigkeit

University of Liege

Serie

IMPRS-MPSSE Seminar

Sprache

en

Hauptthema

Physik

Andere Themen

Physik

Beschreibung

Engineering pump-probe schemes with strong sub and few optical fs pulses has made experimentally feasible to imprint and probe electronic coherence in molecules. It is such coherences that allow a manifestation of a purely electronic time scale, before the coupling to the nuclei takes place. Here I will discuss effects on a longer time scale and in particular how the onset of nuclear motion and subsequently the fate of a chemical reaction can be controlled by creating this electronic coherence through a strong ultra short excitation pulse. Our quantum dynamical computations include the electron-nuclei coupling as well as the photoexcitation and photoionization dynamics due to the coupling to the strong field electric field of the pulse. We show how the ultrafast beatings of the electronic coherences in space and in time are modulated by the different periods of the nuclear motion and the non adiabatic couplings between electronic states and by the photoionization process that can occur during the pump and/or the probe pulses. It is nevertheless possible to follow the spatial and temporal localization of the electronic coherence for a large number of vibrational periods using the probe pulse and monitoring angularly resolved photoelectron distribution or transient absorption as a function of the pump-probe delay time. Examples will be discussed for small molecules, LiH and HCN.

Letztmalig verändert: 30.05.2018, 10:03:31