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Accueil > Séminaires > 2017

Controlling ultrashort charge migration and charge-directed reactivity

Nikolay Golubev, Theoretische Chemie, Universität Heidelberg (Allemagne)

Salle de séminaire IRSAMC, Jeudi 9 Mars, 14h - 15h

In the last years, the rapidly developing attosecond-pulse techniques have given us the unique tool for directly studying and eventually controlling electronic dynamics. Due to the coupling between the electronic and the nuclear motion, the control over the pure electronic step offers an extremely interesting possibility to steer the succeeding chemical reactivity by predetermining the reaction outcome at a very early stage.

One example of physical phenomena where an electronic dynamics significantly affect on the reactivity is the process of ultrafast charge migration. The positive charge created upon ionization of a molecule can migrate throughout the system on a few-femtosecond time scale solely driven by the electron correlation and electron relaxation. Charge migration triggered by ionization appeared to be a general phenomenon taking place both after inner- and outer-valence ionization of molecules.

In the present talk, a few different schemes for controlling the charge migration process by the ultrashort laser pulses will be presented. It will be shown that by appropriately tailored infrared pulses one can stop the pure electronic, few-femtosecond oscillation of the charge, redistributing it along the molecule. It will be also demonstrated on a few examples how one can compute the follow-up nuclear rearrangement, explicitly taking into account the coupling between electronic and nuclear motion.

The presented scheme offers very promising perspectives for studying chemical reactions. In particular, it allows to describe a charge-directed reactivity phenomenon where one can predetermine the outcome of the chemical reaction by localizing the charge on desired side of the molecule.